A Philosophical Study of Some Mediaeval Theories of Signification and Mental Representation and their Bearing on Contemporary Problems in Cognitive Science

by Gyula Klima

0. Introduction: The False Alternatives Of `Realism', `Conceptualism' And `Nominalism' In Mediaeval Philosophy

1. Ontological Alternatives Within The General Semantic Framework Of Pre-Ockhamist Scholasticism

2. A Brief Reconstruction Of Ockham's Semantic Innovations

3. The Independence Of Ontological Reductionism From Semantics

4. The Real Import Of Ockham's Innovations

5. Conclusion: Realism, Conceptualism And Nominalism

0. Introduction: The False Alternatives Of `Realism', `Conceptualism' And `Nominalism' In Mediaeval Philosophy

`Realism', `conceptualism' and `nominalism' are terms that one is most likely to come across in history of philosophy textbooks, presented as ones labeling three major ontological alternatives provided by mediaeval philosophy. The general inadequacy of these labels is perhaps best shown by the desperate efforts to provide further, modified labels, the well-known `moderate' and `extreme' or `exaggerated' versions of the above, in hopes of implying at least a lesser amount of falsehood in hanging these on views of particular mediaeval philosophers.[2]

In what follows, however, it is not my intention to undermine the methodological foundations of `labeling' philosophers or philosophies in general, which are shaky enough in themselves anyway, or to question the use of these labels in particular. Indeed, by the end of this paper I hope to come to certain conclusions which may justify a certain careful usage of these terms, in which I think they do express something fundamental about the overall philosophical attitudes of several, though, as we shall see, mainly non-mediaeval philosophers. On the other hand, I also think that the main borderlines separating major trends in mediaeval philosophical thought lie miles away from the lines suggested by the current, however confused and indeterminate use of these terms. But since nomina sunt ad placitum, and just anyone may have one's own favorite conception of the proper meaning of these terms, a discussion targeting their current usage might easily lapse into verbal quibbles over misunderstood conceptions, a phenomenon painfully familiar in philosophical or scientific polemics.

So what I do wish to do in this paper is rather the following:

1. I present how different ontological alternatives were treated by mediaeval authors within basically the same semantic framework before the advent of Ockham's semantic innovations.

2. I give a short reconstruction of Ockham's semantic innovations.

3. In the light of this reconstruction I wish to point to the logical independence of widely different ontological alternatives from the alternative semantic frameworks thus reconstructed.

4. I discuss how, despite its logical independence, the new semantics changed the research program for ontology and, through this, the paradigm of mental representation in the so-called via moderna trend of late-mediaeval philosophy, which, I conjecture, directly paved the way for modern treatments of ontological and epistemological questions in post-scholastic philosophy.

5. In conclusion I propose an interpretation of the above-mentioned terms which may render them more useful in characterizing certain general philosophical attitudes. I will also remark on the value of these considerations for contemporary research in the philosophy of language and cognitive science.

1. Ontological Alternatives Within The General Semantic Framework Of Pre-Ockhamist Scholasticism

All semantics in mediaeval philosophy begins with Aristotle's famous remark in the beginning of his Perihermeneias to the effect that words signify "passions", i.e., concepts of the soul immediately and it is only through the mediation of these that they signify things. Commenting on Aristotle's remark, St. Thomas Aquinas writes as follows:

... `passions of the soul' must be understood here as conceptions of the intellect, and names, verbs, and speech signify these conceptions of the intellect immediately according to the teaching of Aristotle. They cannot immediately signify things, as is clear from the mode of signifying, for the name `man' signifies human nature in abstraction from singulars; hence it is impossible that it immediately signify a singular man. The Platonists for this reason held that it signified the separated idea of man. But because in Aristotle's teaching man in the abstract does not really subsist, but is only in the mind, it was necessary for Aristotle to say that vocal sounds signify the conceptions of the intellect immediately and things by means of them.[3]

So according to St. Thomas the mode of signification of general terms shows that these signify the natures of individual things in abstraction from the singulars. But these natures cannot exist in abstraction from the singulars. So these abstractions, the universals, are products of the activity of the intellect representing the individual natures of the singulars in an abstract, universal manner. As in his Summa Theologiae St. Thomas remarks:

When we speak about an abstract universal, we imply two things, namely the nature of the thing itself, and abstraction or universality. So the nature itself to which it is accidental that it is thought of or is abstracted or that the concept of universality applies to it exists only in the singulars, but the nature's being abstracted or its being thought of or the concept of universality is in the intellect ... <For example,> humanity that is thought of exists only in this or that man; but that humanity is apprehended without its individuating conditions, which is nothing but for it to be being abstracted, which confers on it the attribute of universality, is an accidental feature of humanity in virtue of its being perceived by the intellect, in which there is a similitude of the nature of the species but not of the individuating principles.[4]

So for St. Thomas the immediate significata of our general terms, like `man', are abstract natures, existing in the intellect. But their ultimate significata are the individual natures of singulars from which the intellect forms its universal concept by abstraction, that is, by thinking of these natures without the individuating conditions that cause them to be the nature of this or that singular.[5]

That the word `man' signifies human nature, however, does not mean that it does not refer to, or, to apply a modern re-coinage of the mediaeval technical jargon, supposit for individual men in a proposition like `Some men are white'. For, as St. Thomas says:

In respect of any name we have to consider two things, namely that from which the name is imposed, what is called the quality of the name, and that to which the name is imposed, what is called the substance of the name. And the name, properly speaking, is said to signify the form, or quality from which the name is imposed, and is said to supposit for the thing to which it is imposed.[6]

So, the term `man' signifies human nature in abstraction from the singulars immediately (in the mind), and signifies individual human natures ultimately (in the things), but normally supposits for the things bearing the nature it signifies, namely individual men. It is only in virtue of some special adjunct that a term is made to refer to what it normally signifies. As St. Thomas says: "the term `man' does not supposit for the common nature unless for the reason of something added, as when it is said `man is a species'."[7]

As is well-known, in systematic treatises on the theory of supposition, the mediaeval theory of reference, this kind of supposition was distinguished as simple supposition, as contrasted with material supposition, when a term refers to itself, as in ``man' is a noun', and with personal supposition, when the term refers to what falls under it, as in `a man runs'.[8] So we can say that for Aquinas a term has simple supposition when it refers to what it (immediately) signifies,[9] while it has personal supposition when it refers to what falls under its immediate significate.

Now the semantic ideas touched upon in these brief quotations from St. Thomas, along with some further considerations concerning predication and the concept of existence, add up to a general semantic theory, which was fairly common to the whole pre-Ockhamist scholastic tradition.[10]

According to the concept of signification involved in this theory, a general term ultimately signifies numerically distinct, inherent natures, forms or properties of individuals, distinguishable from one another by which individuals they belong to. Such a general term signifies these individualized properties because it signifies immediately the universal concept that represents them in an abstract manner in the intellect. Accordingly, a term signifying immediately such a concept is true of a thing just when the individualized property ultimately signified by it in the thing actually inheres in this thing, i.e., if this property actually exists. So when such a term occurs as the predicate of an affirmative categorical sentence, the truth of this sentence ultimately depends on whether the property signified by this term in the thing or things supposited for, that is, referred to, by its subject term actually exists. On the other hand, the subject term of such a sentence supposits for those things which actually bear the property signified by this term. For example, in the sentence `Some men are white' the subject term refers to those things that have human nature, that is, individual human beings. The predicate term, on the other hand, signifies individual whitenesses inhering in white things. The sentence is true if and only if some of the supposita of its subject actually have the property signified by its predicate, that is, if the individual whitenesses of some human beings actually exist.[11]

Now even without going into the finer details of this semantic conception, it clearly seems to imply an enormous amount of ontological commitment. For seemingly, beyond the generally acceptable, "ordinary" ontology of individual substances, it commits itself to huge domains of quite extraordinary entities, indeed, also of several kinds of non-entities. For this semantic conception demands that for every true predicate of a thing there should be a property of the thing actually inhering in it, and also that for every false predicate of the thing there should be a non-actual property signified in it by the predicate in question. Indeed, beyond these individualized properties signified by our general terms in the singulars, this conception also admits universal properties, which, although admittedly are abstracted from the former by the mind, still, exist in a sense, to mediate between the universal terms and their individual instances.

But this specification of the sense of existence in which these universals may be said to be immediately leads us to one of the basic tactics used by mediaeval philosophers working in this semantic framework to reduce the apparent ontological commitments of this conception. The works of these philosophers abound with distinctions of different senses of existence. Consequently, the sense in which ordinary individuals are said to exist was only one among these, although generally enjoying the rank of real existence, as opposed to other, diminished kinds of existence.

St. Thomas, e.g., distinguished between esse reale and esse rationis, the latter being possessed by negative and privative properties, certain relations, universals and propositional complexes.[12] His followers sometimes extended this notion of ens rationis to cover also possibilia indeed, even impossibilia, that is, anything that can be thought of.[13] Scotus and his followers admitted even a third type of existence, supposed to be half-way between esse reale and esse rationis, the so-called esse intentionale, which things were supposed to have when conceived by cognitive powers other than the intellect.[14] If we add to this the distinction between esse essentiae and esse actualis existentiae, the former of which was thought to be possessed by essences even when they did not possess the latter, there being no supposita actually bearing them,[15] we can see how the apparent proliferation of entities or pseudo-entities required by this semantic framework prompted also a proliferation of several types and notions of existence in this tradition.

Ontological commitment with such an abundance of existence-types is certainly not an unequivocal matter. We can indeed say that there are as many types of ontological commitment implied by this framework as many types or notions of existence are distinguished.

Of course, if we apply Quine's standard for ontological commitment, then these distinctions are not much help in reducing the ontological commitment of this conception. For even despite the difference in the way they handled reference, in terms of their theory of supposition, the mediaevals certainly admitted propositions which we would regard as involving quantification over nonexistents.[16] On the other hand, this very formulation, speaking about "quantification over nonexistents", shows that it is possible to employ a notion of existence that has a narrower extension than the range of quantification. In other words this is to say that Quine's notion of existence, whose extension coincides with the range of (unrestricted) quantification, corresponds to the weakest of the senses of existence endorsed by the mediaevals, namely the sense in which whatever can be thought of or referred to by any means is said to exist, in an abstract, atemporal manner.[17] This, however, was by no means the primary sense of the several senses of existence distinguished by the mediaevals, and certainly not one that carried the ontological burden of real existence. The extension of the notion of real existence, as it was understood by the mediaevals, constitutes only a proper subset of the universe of discourse of this semantic framework. This sense of existence is always temporal, expressing actuality. So, this kind of existence was held to be possessed only by actually existing real things, such as individual substances and their real properties, that is, their forms, whether substantial or accidental, actually informing their matter. The items in the other domains of the universe of discourse of this semantic conception were accordingly held to have the other, diminished types of existence touched upon above, or indeed no existence at all.[18]

Now whether one is ready to subscribe to such distinctions of different types of existence or not, one thing about these distinctions should be clear: they did not reduce the ontological commitment of this semantic framework by reducing the number of the semantic values of expressions, but by assigning different, reduced ontological statuses to several classes of them. What did the job of reducing the number of these semantic items, was their identification sometimes across different grammatical categories. Indeed, we may say that most of the substantial metaphysical issues formulated in this framework concerned precisely the identity or difference of such semantic items, the significata or supposita of different expressions.

This is immediately clear for example in the case of the debate concerning the plurality of substantial forms. According to the famous claim of St. Thomas Aquinas, condemned among others by Robert Kilwardby in Oxford in 1277, individual substances do not have different substantial forms corresponding to their different substantial predicates. For St. Thomas, it is the same substantial form that accounts for a man's being a substance, a body, a living, a sensitive, and a rational being, namely his soul. But this, in terms of the above-discussed semantic framework, is to say that the substantial predicates of individual substances have the same ultimate significatum in the same individual. For example, although Socrates is both a body and a man, i.e., a rational animal, his true predicates, `body' and `man', do not signify in him distinct forms: both of these predicates signify in him the same form, his soul, only according to different concepts, which represent this form more or less specifically. Indeed, the other two predicates occurring in the definition of man, `rational' and `animal', and the definition itself as a whole, also signify the same form in Socrates, but again according to different concepts, representing the same individualized form from different aspects, possibly common also to beings other than humans.[19]

But at this point, I think, it is time to give these informal semantic considerations a somewhat more rigorous formulation.

As I said above, the individualized forms, or properties ultimately signified by the same general term are numerically distinct in different individuals. Therefore we can say that such a term signifies these individualized properties in respect of the individuals in which they inhere, i.e., it signifies such a property for this individual, and another for that one, etc. But then we may represent the signification of a general term as a function assigning inherent properties to individuals. In a model theoretical reconstruction of this conception, therefore, a significate of a one-place general term can be denoted as the value of the signification function of this general term for a substance from the domain of our model like this: SGT(T1)(u). (Read: a significate of T1 in u.)[20]

Notice here that SGT is not a two-place function, with a term in its first, and a thing in its second argument-place, but a one-place function, which for a one-place term in its argument-place yields another one-place function, which for a thing in its argument-place yields an individualized property (the property signified by this term in this thing). In this way, applying the same trick, we can give a uniform treatment of the signification of general terms of any arity, and so, generally speaking, we can denote a significate of an n-place general term like this: SGT(Tn)(u1)...(un). (Read: a significate of Tn in u1 and ... and un.)

With this notation at hand we can express the Thomist claim concerning the unity of substantial forms in the following manner:

if S and G are (true) substantial predicates (Species and Genus) of the same substance u, then SGT(S)(u)=SGT(G)(u).

Accordingly, the opposite claim of the plurality of substantial forms will, of course, take the form of the denial of such identities.

But the above treatment of many-place terms also allows us the reconstruction of another widely disputed question: that of the identity of relations with their foundations. The claim of those who held that relational properties are identical with the absolute properties founding the former, in the way the whitenesses of Socrates and Plato found their similarity, may be expressed as follows:

if R is a relational term which is true of two substances u and v, founded by the absolute property of u signified by the absolute predicate F, then SGT(R)(u)(v)=SGT(F)(u).

Also a great deal of ontological debates centered around questions regarding the distinctness of the significate of the predicate `est', in the sense of actuality, from the significates of other, especially substantial predicates of a thing, that is, the distinction of existence from essence. The famous Thomist claim of the real distinction between essence and existence in creatures can be represented in this reconstruction by saying that, since for Aquinas substantial predicates of a thing signify the nature of this thing, if S is a substantial predicate of a creature u, then SGT(S)(u) is distinct from SGT(`est')(u)(t).[21] On the other hand, since the name `God' signifies the divine essence according to St. Thomas, his claim that in God, nevertheless, essence and existence are not distinct from one another can be expressed by the following identity: SGT(`God')(God) = SGT(`est')(God)(t).

Many others held, however, the view that essence and existence are not distinct even in the creatures, that is to say, that the significates of substantial predicates of individual creatures are identical with what the verb `est', in its primary sense, expressing actual, real existence, signifies in them.

Now I think already these few examples are sufficient to show how several metaphysical problems of the pre-Ockhamist mediaeval tradition presupposed the same general semantic framework, and how the identification of the semantic values of different expressions contributed to reducing the ontological commitments of this framework. So in view of these considerations we can see actually how unjust it was on Ockham's part to charge his predecessors with what he identified as "the root (principium) of many errors in philosophy: to want that to a distinct word there always correspond a distinct significate, so that there is as much distinction between the things signified as between the nouns or words that signify".[22] Nevertheless, it was in this spirit that he discarded the semantic framework that for him seemed to be committed to this "root of many errors", in favor of a total reinterpretation of the relationships between language, mind and reality.

2. A Brief Reconstruction Of Ockham's Semantic Innovations

A presentation of Ockham's semantic innovations has to start with an account of his distinction between absolute and connotative terms. An absolute term signifies equally and in the same way all its significata. A connotative term, on the other hand, has both primary and secondary significata, and signifies its primary significata only in relation to its secondary significata or connotata. As we could see, in the older framework the significations of one-place general terms could be characterized as semantic functions assigning individualized forms or properties to individual substances. For Ockham, however, the significations of absolute terms are just sets of their significata. So absolute terms are general names of their significata, these being, according to Ockham, either substances, like men, trees or stones, or inherent, individual qualities, like this whiteness, that blue color or this concept of, say, horses, inhering in Socrates's mind. So if T is an absolute term, then a significate of T is just an element of a subset of the universe of discourse.[23]

The signification of a connotative term is more like the signification of terms in general in the older framework, for Ockham's connotative terms also signify certain things in respect of others. The difference, however, is that while in the older framework general terms signified inherent forms in respect of individual substances, Ockham's connotative terms, conversely, signify individual substances in respect of their inherent qualities or other individual substances.[24] For example, while on the older view the term `white' signified individual whitenesses of individual substances, for Ockham the same term signifies individual substances, connoting their individual whitenesses.[25] So we can bring out the contrast between Ockham's and the older view by the following equations:

Older view: SGTa(`white')(Socrates)= Socrates's whiteness

Ockham's view: SGTo(`white')(Socrates's whiteness)=Socrates

But Ockham's innovations, of course, concerned not only denominative terms, a subclass of the class of connotative terms, but connotative terms in general, i.e., terms which have both primary and secondary significata, indeed, in Ockham's view all terms belonging in categories other than substance and quality.[26]

For example, the relative term `father' signifies those men who have sons in relation to their sons:[27]


In contrast to this, on the older view, heavily criticized by Ockham,[28] the term `father' was taken to signify a relation, "fatherhood", holding between two persons, the son and his father:

SGTa(`father')(father)(son)=fatherhood of father

Indeed, this formulation immediately shows why the question whether the same person's having several sons multiplies his fatherhoods so naturally arises in this context.[29] On the other hand, it also shows why Ockham did not have to worry about such questions: for him what such a term signifies are just the things which it can stand for in propositions, namely its possible supposita, signified in relation to other things, the term's connotata. The only thing Ockham had to worry about concerning his ontological program was the elimination of any apparent reference to things seemingly belonging in categories other than substance and quality. To this end he used basically two tactics, one of which can be called 1. elimination by identification, and the other 2. elimination by definition.

1. The first tactic served for Ockham and his followers to handle the reference of abstract terms. In the case of absolute terms in the category of substance, they simply identified the supposita and significata of abstract terms with those of the corresponding concrete ones. So `humanitas', e.g., was no longer conceived as signifying or referring to some abstract entity different from individual men, but to the individuals themselves.[30] In the case of connotative terms the significata and supposita of abstract terms were identified either with the significata, or, according to Buridan at least in some cases more properly, with the connotata of the corresponding concrete terms.[31] In fact, Ockham also entertained the idea of identifying the supposita of abstract relative terms with the sets of the relata of the corresponding concrete terms, construing them as collective names. According to this conception the term `similitude', for example, refers to individual things that are similar collectively (coniunctim), that is, to a number of individuals at once, but without referring to any of them, just like the terms `people', `army', `crowd' or `company'.[32]

2. The second tactic was used to eliminate apparent signification or connotation of, or reference to, entities that could not plausibly be identified as either substances or qualities. Consider for example the term `blind'. It evidently does not signify animals absolutely, but only by connoting a certain property, namely lack of sight. However, this property cannot be identified as a positive quality of a substance, being by its very concept rather a lack of a positive quality, namely sight. This is precisely what is spelled out by the nominal definition of this term, an expression which is synonymous with it, but showing in detail the complex conceptual structure hidden by the syntactic simplicity of the term. Indeed, several of his formulations suggest that according to Ockham all connotative terms are subordinated to complex concepts, because all connotative terms have such nominal definitions, namely complex expressions subordinated to the same complex concept and hence having the same meaning, but at the same time by their syntactic structure revealing the structure of this complex concept.[33] For example, for the sake of simplicity let's assume that `blind' has as its nominal definition `not sighted'. Then `blind' is no longer to be regarded as semantically primitive, but its significata are to be constructed as a function of the significata of the constituents of its nominal definition. But providing this construction means that there is no need to suppose that there is a curious kind of property of things, blindness, which cannot be identified with either a substance or a quality: what the term `blind' signifies are substances, connoting particular qualities, namely individual sights that are not actual in their subjects, and the concept of negation, a certain syncategorematic mental act of individual human minds modifying the way other concepts are related to things, in this particular case, signifying precisely the absence of the connoted sight.[34]

Generally speaking, by this method Ockham might hope eventually to eliminate (at least in principle - an important qualification of all kinds of reductionist programs) all apparent reference to entities other than substances and qualities, by supplying in the last analysis nominal definitions containing only syncategoremata, signifying qualities of the mind, and absolute terms, signifying substances or their qualities. To be sure, in the above example, `sighted' is still a connotative term, so it demands further analysis. In fact, since nothing guarantees that in any nominal definition we may supply for a connotative term another connotative term will not crop up again, by this move Ockham stakes his semantics on his ontological program.

It is Buridan who could safely get out of this difficulty, by admitting the existence of simple connotative concepts.[35] Indeed, he could do so without any ontological compromise. For his simple connotative concepts may signify the same absolute things ad extra as Ockham's complex connotative concepts. The only difference is that these are not constructed out of simple absolute concepts plus syncategoremata as Ockham's putative connotative concepts, but they simply signify absolute things connoting others as adjacent or non-adjacent to what they signify. So the appearance of connotative terms subordinated to these concepts in nominal definitions does not force further analysis. On the other hand, one may also point out that Buridan's option helps only to the extent it enhances the vocabulary available for analysis, which alone may hardly guarantee universal success.

But whatever are the merits and demerits of Ockham's ontological program, it surely gave a new direction to later ontological research.

3. The Independence Of Ontological Reductionism From Semantics

From the above presentation it may seem that the basic import of Ockham's semantic innovations was a genuine reduction of the ontological commitment of semantic theory. Indeed Ockham himself seems to discredit the older semantics precisely for its apparently enormous ontological commitments. However, as I remarked above, the tactic of identifying the semantic values of different expressions was open also in the older framework. Also it is a simple fact that by our very awareness of time and unrealized possibilities we can think of, refer to, or signify items that are not actually realized. So it seems to be a mere verbal difference whether we are ready to apply the verb `exists' and its equivalents in a thinner, reduced sense to items in our universe of discourse beyond the actually existing ones or not.[36] In any case, Ockham himself, although he insists that there is not "another tiny world" reserved for non-real things and what is not real is nothing at all,[37] finds no faults with referring to things that do not actually exist, although he refuses to allow a thinner sense of existence to be applied to these. So despite his apparent concern with ontological reduction, it seems that Ockham's program is rather contingently connected to reducing ontological commitment, for in principle the same amount of reduction could be achieved also in the older framework, by using the tactic of identification and allowing only one, restricted sense of existence, to be denied to items in our universe of discourse that fall beyond the sphere of actually existing things.[38]

But if not in the ontological reductions, then in what does the real import of Ockham's innovations consist? I suggest that in transforming the very idea of the task of ontological research and through this in transforming the paradigm of the theory of mental representation in a manner that even nowadays influences our thinking about the subject.

4. The Real Import Of Ockham's Innovations

As we could see, the reductionist tactic used by Ockham that was not so used in the older framework was what I called elimination by definition. We could also see that in the ideal, "finished" case, this tactic would eliminate all kinds of fortuitous terms, hiding by their syntactic simplicity a complex conceptual structure, consisting only of absolute concepts (and possibly some simple connotative concepts) and their "glue", our syncategorematic concepts.

Now regarding this tactic we can say that the real value of such an analysis for the ontologist is not so much the sheer possibility of reducing the number of kinds of entities his theory is committed to, as the possibility of showing what there really is in external reality. For by this analysis, it seems, we may be able to identify those of our concepts that anchor our thoughts immediately and directly to the building blocks of the external world, thereby uncovering its real, independent structure, which without such a revelation is ordinarily hidden by the web of conceptual structures woven by our minds for mere convenience of expression, and for similar, merely accidental, pragmatic and historical reasons.[39] These "anchors of thought", for Ockham, are our absolute concepts. These are the ones that we acquire by direct acquaintance with things in our natural environment, the ones that are naturally caused in us by external things and which are therefore the immediate natural signs of these things.[40]

And it is at this point that the real import of Ockham's innovations comes in. For the causal story Ockham has to tell us about the acquisition of our absolute concepts, there being no place for universal natures in his universe, not even in their tokens in individuals, is based on the notion of efficient causality. In contrast to this, the older framework had a story to tell us about concept acquisition in terms of formal causality. In what follows I wish to argue that this seemingly slight shift in the paradigm of the account of mental representation had a tremendous significance with far-reaching consequences.[41] (Just remember what Aquinas says quoting the Philosopher: parvus error in principio magnus est in fine.)

The efficient causality model fixes the relation of natural signification on the basis of natural laws systematically connecting causes with their effects. But all that these natural laws guarantee is the systematic correspondence between causes and their effects, supposing the normal course of nature. The effects, however, may be essentially different from their causes, and may, therefore, be produced also by other essentially different causes too, which means that it is clearly possible that an absolute concept be caused in our intellects by a cause which is totally alien from what this concept is supposed to represent.

On the other hand, the formal causality model inherent in the older semantic framework is based on the idea that the natures informing the things of external reality, and making them to be what they are, are the very same natures that inform our minds when we have the concepts of these things. To be sure, this sameness of nature is not a numerical identity: the concept of man I have in my mind is a distinct entity from the nature of Socrates making him a man. However, what necessarily connects these two distinct entities is that they are tokens of the same nature, indeed, they are the same nature, in the same way as different tokens of the same word are the same word, despite the fact that they are numerically distinct entities.[42] (Just recall Aquinas speaking about the same nature whether in the thing or in the intellect.)

To see the difference between these two models in somewhat more exact terms let's take a look again at the ways the significations of substance-terms were construed in the two semantic frameworks discussed above.

In what I called the older framework, the signification of such a term could be reconstructed as a function assigning individualized instances, or tokens of the nature signified by this term in the individuals having this nature, to the individuals. Now since the concepts of individual human minds representing this nature are again but tokens of the same nature, we can say that these concepts should be construed as values of the same function for individual human minds as its arguments.

On the other hand, although these concepts are individual tokens of the same nature in that they inhere in this or that particular mind, since they are obtained by the mind's activity through a process of abstraction, in relation to the individual tokens of the same nature informing the individuals they are universal. Indeed, as I said in the beginning, the universal term subordinated to such a concept was held to be universal precisely on account of this universal relation of the concept to the other tokens of the same nature. For the word was held to signify precisely those individualized natures which the corresponding concept represented in a universal manner. So the concept itself also should be regarded as a function, assigning individualized natures to individuals, those natures which the word subordinated to it ultimately signifies. So if CON(m)(T) is a concept subordinated to the term T in a mind m, and u is some extramental individual, then we can say that:

SGTa(T)(m)=CON(m)(T) and SGTa(T)(u)=CON(m)(T)(u)

Now what is important about these concepts from our present point of view is that they are individuated both by their subjects and their objects. For from the above characterization of concepts it follows that, for any u and m:

CON(m)(T1)=CON(m)(T2) iff CON(m)(T1)(u)=CON(m)(T2)(u)[43]

That is to say, two concepts may differ either because they inhere in different minds, or, more importantly, because they are concepts of different objects. I say, "more importantly", because the sheer numerical difference between concepts belonging to different minds is a rather trivial matter and is usually disregarded when conceptual differences are under discussion. For example, it is a trivial matter that Euclid and Aristotle had numerically different concepts of a triangle, only because they were distinct individuals. The more interesting difference between concepts is the difference e.g. between Euclid's and Bolyai's concept of a triangle, on account of the difference between the thought-objects they had in their minds. It is precisely the lack of this kind of difference that entitles us to say that Aristotle after all had the same concept of a triangle as Euclid did, despite the numerical distinction of the mental acts by which they conceived triangles.

So if we disregard the trivial numerical difference between concepts on account of their subjects, then we can say that what accounts for the distinction or identity of concepts is whether they concern the same thought-objects or not. And note here that this criterion of identity for concepts is not something that we have to stipulate: this is a plain corollary of the way we described concepts, as being tokens of the same nature as their objects.

In contrast to this, on Ockham's account of the matter, the identity or difference of their objects need not necessarily enter the identity-conditions of concepts. Of course we may, as Ockham and his followers in fact did, stipulate that two concepts are distinct if and only if they concern different objects, but this is an extra stipulation that does not follow from the characterization of concepts in this framework. A concept for Ockham is but a quality of mind distinct by place and subject from its objects, connected to them by the logically contingent relation between effect and cause. But since, generally speaking, the same effects in principle may be produced by different causes, the identity or difference of their objects is not necessarily involved in the identity-criteria of concepts on this characterization.[44]

The skeptical implications of this conception of mental representation were soon recognized by the Avignon commission examining Ockham's doctrines and were developed into a fully-fledged skeptic doctrine by the "mediaeval Hume", as he is sometimes called, Nicholas of Autrecourt. For, concluded the Avignon commission, if the object and its concept are connected by the relation of efficient causality alone, it may well be the case that the effect, the concept of the object, is produced by a superior agent, God, without the presence of the object.[45] But if this may happen in this or that particular case, then nothing prevents the possibility of this being always the case, Nicholas argued further.[46]

I think it is quite obvious how small, logically, is the further step to be taken to get from here to Descartes's Demon, or its modern, suitably secularized and ethicized version, the Evil Scientist with his envatted brains. Also it is the presuppositions of the same model of mental representation that later on called for desperate efforts to explain the mysterious match between mental and external structures, if there was supposed to be any, in terms of direct causality, occasionalism, or pre-established harmony; or to explain it away as naturally surpassing our cognitive capacities altogether.

Note that in the earlier, formal causality model of mental representation no similar cognitive predicaments can occur: if I have a donkey-concept, than it cannot be but of donkeys. I think this is precisely the point of Aquinas's seemingly cryptic, but repeatedly made remark that "the intellect is not deceived about its proper object" (intellectus non decipitur circa obiectum proprium), namely the quiddity of material things. By my donkey-concept being what it is, a token of the same nature that informs donkeys, I can conceive but donkeys.

To be sure, it may well be the case that I mistakenly judge this particular individual to be a donkey, when it is not a donkey, but say, a pony. This is what Aquinas speaks about when he says that the intellect may be deceived per accidens about its proper object, namely when it mistakenly subsumes an individual under another concept, forming a judgment about it. What is excluded by this model, however, is that I have a donkey-concept which is not of donkeys, but of, say, electronic impulses from the Evil Scientist's computer.

On the other hand, in the framework of the efficient causality model, since the identity of their objects does not enter the identity conditions of mental acts, it may very well be the case that a poor envatted brain has a mental act, which is exactly like my donkey-concept, with the only deplorable difference that the brain does not conceive by it donkeys but only electronic impulses. And so, again, since mental acts have identity-conditions of their own, irrespective of their objects, it may very well be the case that my concept is indistinguishable from that of the envatted brain, so there is no way of telling whether I myself, who is thinking about this problem, am not an envatted brain.

In the formal causality model, however, the objects of concepts cannot be swapped without affecting their identity. So it simply cannot be the case that I have a genuine donkey concept, by which I conceive donkeys, which is indistinguishable from the fake donkey concept of an envatted brain conceiving by it only electronic impulses. Also, since if I have a genuine donkey concept, then my concept is an instance of the same nature that informs donkeys, it cannot be the case that I have a genuine donkey concept and I don't conceive by it donkeys, but only electronic impulses. Indeed, it cannot be the case either that I have a genuine concept of brains-in-a-vat, conceiving by it only electronic impulses instead of real brains in a vat. But I can conceive a real situation only by genuine concepts. So I conceive a real situation as described in the brains-in-a-vat story only if I have a genuine concept of brains-in-a-vat. But then I am not a brain in a vat.

So as understood in the formal causality model, the very description of the situation guarantees that whatever mental acts an envatted brain has, since by them it conceives only electronic impulses which I don't, while I have to conceive things, which it doesn't (at the very least some real envatted brains), its mental acts are different specie from mine. So the description of the situation entails that I am not in its situation, that is, I am not an envatted brain. So Descartes's Demon, or the brains-in-a-vat story and their kin can present difficulties only for the efficient causality model of mental representation, and so may, perhaps, be utilized not so much as arguments for skepticism, but rather as arguments against this model.

5. Conclusion: Realism, Conceptualism And Nominalism

In conclusion of this discussion let me return for a while to the "philosophical labels" mentioned in the introduction, and propose for them a certain interpretation which, in the light of the above reflections, may be useful in characterizing certain general philosophical views on mental representation.

In the history of philosophy textbooks referred to above, Ockham is usually presented as a nominalist or a conceptualist and sometimes also as a skeptic, although the latter label has been vigorously challenged by many recent historians.[47] I think the arguments and the textual evidence for the claim of these historians are conclusive: Ockham himself was by no means a skeptic, for he did believe that human cognitive powers are capable of adequately capturing the essential features of external reality. Nevertheless, what even so justifies to a certain extent the charge of skepticism is that in his zeal for ontological reductions, by changing the concept of signification, Ockham shifted the burden of natural signification from formal causality to efficient causality, thereby making it dependent on a contingent natural order of creation, suspendable at any time, if by no-one else, at least by its Maker.

To be sure, creation and natural order are contingent and subject to God's almighty power in the older framework too. The difference is that on the older view God's universal design pervades the whole of creation including conceptual structures of the human mind as well.[48] So even if it is quite possible that God could have had a different plan with a different design and different creatures having different cognitive capacities, what is excluded by this conception is that in this creation with the conceptual capacities we actually have at our disposal we should be systematically deceived by a Great Deceiver in a way that his plot could never in principle be disclosed by us.

It is this kind of homogeneity of real and mental structures that was severed by Ockham's paradigm-shift, which opened up the logical possibility of a systematic, essential and in principle undetectable mismatch between these structures. Nevertheless, Ockham did believe that as long as we can suppose the normal workings of nature our cognitive powers are in fact capable of grasping the essential features of independently existing external reality.[49] So we can say that far from being a skeptic, Ockham was, in one sense of the term, the first modern realist. The sense of the term I have in mind is characterized by Crispin Wright in the following words:

The view of the world which Putnam calls metaphysical realism is nothing very precise. It involves thinking of the world as set over against thought in such a way that it is only by courtesy of a deeply contingent harmony, or felicity, that we succeed, if we do, in forming an overall picture of the world which, at least in its basics, is correct. This is what commits the metaphysical realist to the possibility that even an ideal theory might be false or seriously incomplete. And the same kind of thinking surfaces in the idea that the world comes prejointed, as it were, into real kinds, quite independently of any classificatory activity of ours. For once one thinks of the world in that way, one is presumably committed to the bare possibility of creatures naturally so constituted as not to be prone to form concepts which reflect the real kinds that there are. The real character of the world and its constituents would thus elude both the cognition and the comprehension of such creatures.[50]

I think this description excellently fits both the actual picture suggested by Ockham's model and its implications, developed mainly by others, influenced in one way or another, after some centuries' while largely unknowingly, by Ockham's new paradigm. One type of reaction to this picture was certainly skepticism. But those who still believed in some match between thought and reality devised several ways to account for it. Earlier I mentioned causality, occasionalism and the idea of pre-established harmony. I think that all these may find their place under the concept of realism in that they think of the external world as absolutely unaffected by our thinking, and its intact structure as to be discovered and mirrored by our minds either through the things' action on our cognitive faculties, or through the graceful activity of a superior agent.

A radically different reaction to the same picture is one that reverses the direction of explanation and says that what accounts for the match between our conceptual structures and the essential categories of reality is that it is our very concepts that structure this reality for us, so no wonder we find what our minds posited there. To be sure, the reality thus constituted may be just a mere phenomenal reality, the world as it appears to us, human beings, endowed with just the kind of cognitive powers we happen to have. So even if the Ding an Sich may or may not have some structure of its own, that structure is necessarily beyond our reach. But at least in the phenomenal reality, constituted by our own concepts, we may feel safely at home. I think it is this type of attitude that, with its reliance on the priority of our conceptual structures, may justly be called conceptualism.

Finally, we have many modern examples of the kind of reaction to the same picture that says that we simply should not be bothered by any kind of mysterious match between the categorial structure of thought and reality, but should rather choose and stipulate those forms of expression of our generalizations that promise the best predictive success and fit in the simplest and easiest way into the present, well-established forms. This kind of attitude, with its disregard for either real or conceptual structures and its obsession with stipulating certain convenient uses of expressions, I think may duly be termed nominalism.

As can be seen, what I called the "older", or "formal causality" model of mental representation could hardly find its place under any of these characterizations. In fact, in this paper I have tried to argue that it was Ockham's paradigm-shift that set the stage for these alternatives, and for the demise of the older model together with its own, rather different ontological alternatives.[51] But it is precisely for this reason that a reconstruction of the alternative semantics involved in this older model may shed some fresh light also on our modern problems, presupposing so much in their formulations from a historically rather contingent conceptual heritage.[52]

[1] Reprinted from S-European Journal for Semiotic Studies Vol. 3 (4) 1991, pp. 587-618, with minor corrections by the author.

[2] It is not unusual in the secondary literature to characterize these alleged ontological alternatives in terms of distinguishing between universale ante rem, in re and post rem. For the original use of this distinction consider the following: "Patet, secundo, doctorum sententia dicentium quod triplex est universale, scilicet ante rem individuam, ut idea, in re, ut forma multis rebus communicata, et post rem, ut species vel signum priorum." John Wyclif: Tractatus de Universalibus, (ed. I.J. Mueller), Clarendon Press, Oxford, 1985. c.2. p.69. Cf. also: "Isti autem duplici modo universalis <Platonis et Aristotelis> superadditur modus tertius; videlicet quod species quae est in intellectu abstracta a rebus dicitur universale, eo quod habet respectum ad plura, non quia de pluribus praedicatur, sed quia pluribus est similis. ... Et hinc forte habuit ortum illa distinctio quod tripliciter est universale, ante rem, in re, et post rem. Nam universale primo modo dictum est ante rem, quia causat res. Secundo modo dictum est in re, quia est idem essentia cum rebus. Tertio vero modo est post rem, cum sit species a rebus abstracta et ab ipsis causata." Aegidius Romanus, 1SN, d.19. pars 2., q.1. Utrum in divinis sit totum universale?, Venetiis, 1521, Minerva, Frankfurt/Main, 1968. Concerning alleged "ontological extremities" in mediaeval philosophy see J. A. Trentman's Introduction to his edition of Vincent Ferrer's Tractatus de Suppositionibus, Stuttgart-Bad Cannstatt, 1977. esp. pp.20-30.

[3] in Peri lc.2.n.5. Aristotle: On Interpretation: Commentary by St. Thomas and Cajetan, tr. J.T. Oesterle, Marquette University Press, Milwaukeee, Wisconsin, 1962, p.25.

[4] "Cum dicitur universale abstractum, duo intelliguntur, scilicet ipsa natura rei et abstractio seu universalitas. Ipsa igitur natura cui accidit vel intelligi vel abstrahi vel intentio universalitatis non est nisi in singularibus; sed hoc ipsum quod est intelligi vel abstrahi vel intentio universalitatis est in intellectu ... Humanitas quae intelligitur non est nisi in hoc vel in illo homine; sed quod humanitas apprehendatur sine individualibus conditionibus, quod est ipsam abstrahi, ad quod sequitur intentio universalitatis, accidit humanitati secundum quod percipitur ab intellectu, in quo est similitudo naturae speciei et non individualium principiorum." ST1 q.85.a.2.ad2. Unless otherwise indicated, as in the note above, translations in this paper are mine.

[5] "Non enim oportet si hoc est homo, et illud homo, quod eadem sit numero humanitas utriusque, sicut in duobus albis non est eadem albedo numero; sed quod hoc similetur illi in hoc quod habet humanitatem sicut illud: unde intellectus, accipiens humanitatem non secundum quod est huius, sed ut est humanitas, format intentionem communem omnibus." 2SN d.17.q.1.a.1.

[6] "... in quolibet nomine est duo considerare: scilicet id a quo imponitur nomen, quod dicitur qualitas nominis, et id cui imponitur, quod dicitur substantia nominis. Et nomen, proprie loquendo, dicitur significare formam sive qualitatem a qua imponitur nomen; dicitur vero supponere pro eo cui imponitur." 3SN d.6.q.1.a.3.

[7] "Unitas autem sive communitas humanae naturae non est secundum rem, sed solum secundum considerationem; unde iste terminus `homo' non supponit pro natura communi, nisi propter exigentiam alicuius additi, ut cum dicitur, `homo est species'." ST I. q.39.a.4., cf. ST III. q.16.a.7.

[8] For good bibliographies on the vast recent literature on supposition theory see e.g.: E.J. Ashworth: The Tradition of Mediaeval Logic and Speculative Grammar, Toronto, 1978; N. Kretzmann-J. Pinborg-A. Kenny: The Cambridge History of Later Mediaeval Philosophy, Cambridge, 1982. For more recent references see: N. Kretzmann (ed.): Meaning and Inference in Mediaeval Philosophy, Kluwer Academic Publishers, 1989.

[9] For a detailed discussion of Aquinas' treatment of the problems connected with the supposition of `man' in `man is a species' see my "`Socrates est species': Logic, Metaphysics and Psychology in St. Thomas Aquinas' Treatment of a Paralogism", in: G. Klima: Ars Artium: Essays in Philosophical Semantics, Mediaeval and Modern, Budapest, 1988, also to appear in K. Jacobi (ed.): Acts of the 8th European Symposium of Mediaeval Logic and Semantics, Munich, Philosophia Verlag, 1990. Cf.: Walter Burleigh: De Puritate Artis Logicae Tractatus Longior with a revised edition of the Tractatus Brevior, (ed. Ph. Boehner) St. Bonaventure, N.Y., 1955, c.3. p.7.

[10] For a complete technical description of a model theoretical semantics constructed along the lines described here see the Appendix of my "Understanding Matters from a Logical Angle", in Gyula Klima: Ars Artium: Essays in Philosophical Semantics, Mediaeval and Modern, Budapest, 1988. Further formal approximations of the finer details of St. Thomas' semantic theory can be found in the last two essays of the same volume. By an attempt to characterize what I think to be a common semantic framework in pre-Ockhamist scholasticism, I do not mean to imply that there existed no substantial differences between particular semantic views of pre-Ockhamist mediaeval thinkers. My concern in this paper, however, is to contrast the paradigmatically different ways of constructing semantic theory before and after the advent of Ockhamist semantics, so for the most part I will disregard individual differences that are accidental from this point of view.

[11] Concerning this theory of predication in general, the inherence theory, as opposed to the identity theory see L.M. de Rijk's Introduction to his edition of Abaelard's Dialectica, Assen, 1956, pp.37-38; also D.P. Henry, Medieval Logic and Metaphysics, London, 1972, pp.55-56. Concerning St. Thomas's inherence theory in particular see H.Weidemann, "The Logic of Being in Thomas Aquinas", in: S. Knuuttila-J. Hintikka (eds.), The Logic of Being, Dordrecht, Holland, 1986; R.W. Schmidt S.J., The Domain of Logic according to Saint Thomas Aquinas, The Hague, Martinus Nijhoff, 1966. See also the interesting note in Trentman, op. cit., p.97. For formal reconstructions of these predication theories see again my Ars Artium.

[12] For a detailed discussion of St. Thomas's distinction see my paper: "The Changing Role of Entia Rationis in Mediaeval Semantics and Ontology: A Comparative Study with a Reconstruction", to appear in Synthese, 1991.

[13] Cf.: "Nam multa cogitantur ab intellectu nostro quae in se non habent reale esse, etsi cogitentur ad modum entium, ut patet in exemplis adductis de caecitate, relatione rationis, etc. Item multa cogitantur quae sunt impossibilia et modo possibilium entium finguntutr, ut chymaera, quae non habent aliud esse quam cogitari." Francisco Suarez: Disputaciones Metafisicas, disp.LIV. sect.1. n.7. Editorial Gredos, Madrid, 1966. p. 394. Cajetan also included chimeras among entia rationis in his commentary on St. Thomas' De Ente et Essentia. Cf. also: John Poinsot (Iohannes a Sancto Thoma): Tractatus de Signis (part of his Cursus Philosophicus, ed. by R.A. Powell), University of California Press, 1985. pp.49-52. (Quid sit ens rationis in communi et quotuplex)

[14] "... triplex est esse in universo: scilicet esse reale, esse intentionale et esse rationis. Esse reale est illud quod convenit rei ut existit formaliter et in natura propria et tale esse non convenit nisi singulari vel ei quod habet esse in singulari, quia solum singulare existit in natura propria per se et primo; universalia autem non existunt nisi ut habent esse in singularibus de quo esse intelligitur illud Philosophi in Praedicamentis: `destructis primis impossibile est aliquod aliorum remanere'. Esse vero intentionale est illud quod convenit rei ut habet esse representative sive esse representatum in aliquo alio ente reali, et quia representari in aliquo alio obiective indifferenter convenit tam universali quam singulari, ideo esse intentionale convenit tam universali quam singulari, ideo esse intelligibile non magis appropriat sibi esse universale quam singulare nec econverso, et tale esse intentionale est debilius esse reali et ideo semper fundatur in ipso licet obiective. Esse vero rationis convenit rei ut habet esse conceptus in sola consideratione intellectus operantis et tale, cum sit esse diminutum, semper praesupponit alterum duorum praecedentium." Fr. Guillelmus Alnwick O.F.M.: Quaestiones Disputatae de Esse Intelligibili, (ed. P. Athanasius Ledoux, O.F.M.) Ad Claras Aquas, Florentiae, 1937. p.6. Cf. J. Duns Scotus: Opus Oxoniense, I. d.36.q.unica. St. Thomas also uses the term esse intentionale, see e.g. ST1 q.56.a.6.; ST1 q.67.a.3.; De Ver q.22.a.3.; 4SN d.44.q.2.a.1.; in De Anima lb.2.lc.14, lc.24. etc.

[15] Cf. e.g. "... non sequitur `homo est ens ergo homo est', quia sicut ista est vera `homo est animal' propter convenientiam intellectuum, similiter dico quod ista est vera `homo est ens' propter convenientiam intellectuum entis et hominis. Unde dico quod ibi `ens' non sumitur pro significato entis actu, sed pro intellectu ipsius. Et ideo non sequitur `homo est ens, ergo homo est'." Quoted by D.P. Henry: "Some Thirteenth-Century Existential Disputes: Their Identification and Its Status", in: P. Osmund Lewry O.P. (ed.) The Rise of British Logic, Toronto, 1985, pp.226-227. Cf. further Aegidius Romanus: Theoremata de Esse et Essentia, (ed. E. Hocedez), Louvain, 1930. XIII. pp.78-84.; Henricus de Gandavo: Quodlibet I, Opera Omina, vol. V, (ed. R. Macken), Leuven University Press-E.J. Brill, Leiden, 1979. q.9. See also S. Ebbesen: "The Chimaera's Diary", in: S. Knuuttila-J. Hintikka: The Logic of Being, Helsinki, 1987.

[16] For example: "Nota quod qoddam potest esse licet non sit, quoddam vero est." St. Thomas Aquinas: De principiis naturae, c.1.

[17] It is this sense of being that Burley called "maximally transcendent" (ens maxime transcendens). Walter Burley's De Ente, (ed. H. Shapiro), Manuscripta, 7(1963), pp.107-108. Cf.: "Nearly everyone who mentioned Gregory of Rimini at all pointed out that he had introduced a distinction between three senses of such terms as aliquid and ens. In the first and broadest sense, everything which was signified complexly or incomplexly was something, whether it was true or false or even impossible. In the second sense, every true thing which was signified complexly or incomplexly was something. In the third and strictest sense, only things existing in nature, whether substance or accident, creator or creature, could count as something." E.J. Ashworth: "Theories of the Proposition: Some Early Sixteenth Century Discussions", Franciscan Studies, 38(1978), pp.88-89. Of course, this does not mean that Quine commits himself to all kinds of intelligibilia. His tactic to reduce ontological commitment is to eliminate "apparently" referring expressions by means of quantified formulae in which the variables may be interpreted as ranging only over "legitimate" entities (in the vein of Russell's analysis of definite descriptions). This is the tactic comparable to Ockham's which I call elimination by definition (see below).

[18] For an interesting example of this latter opinion see R. Lambertini: `Resurgant Entia Rationis: Matthaeus de Augubio on the object of Logic', Cahiers de l'Institut du Moyen-Age Grec et Latin, 59(1989), pp.3-60, esp. p.29. Lambertini's paper supplies also a wealth of further references.

[19] Cf. De Ente c.3.

[20] SGT(T1)(u)Î WÈ {0}, where W is the universe of discourse and 0 is a zero-entity falling outside the universe of discourse. The case SGT(T1)(u)=0 (read: a significate of T1 in respect of u is 0) represents the situation when the term in question signifies nothing in u. This may be the case when a predicate simply does not apply to certain things, like e.g. colour predicates to numbers.

[21] Here t is a time-point connoted by the present tense of the verb. For more on technical details, and complete description of formal semantic systems constructed along these lines see again G. Klima: Ars Artium: Essays in Philosophical Semantics, Mediaeval and Modern, Budapest, 1988. Since in this paper I am mainly concerned with the philosophical implications of the paradigmatically different ways mediaeval thinkers constructed their semantic theories, formalizations in this paper serve only to indicate how fundamental semantic ideas of the mediaevals may be reconstructed in a model theoretical framework. These simple formal devices are, therefore, only meant to facilitate the identification of conceptual differences of crucial importance.

[22] "Et hoc est principium multorum errorum in philosophia: velle quod semper distincto vocabulo correspondeat distinctum significatum, it quod tanta sit distinctio rerum significatarum quanta est nominum vel vocabulorum significantium ..." Guillelmi de Ockham Summula Philosophiae Naturalis, ed. S. Brown, Opera Philosophica, vol. VI., St. Bonaventure N.Y., 1984, p.270.

[23] SGT(T)Î U, where U=SG(T), the signification of T, is a part of W. "Hoc enim nomen `homo' non significat primo unam naturam communem omnis hominibus, sicut multi errantes imaginantur, sed significat primo omnes homines particulares ... Ille enim qui primo instituit hanc vocem `homo', videns aliquem hominem particularem, instituit hanc vocem ad significandum illum hominem et quamlibet talem substantiam qualis est ille homo. Unde de natura communi non oportuit eum cogitare, cum non sit aliqua talis natura communis." Ockham: Summa Logicae, ed. Ph. Boehner, Opera Philosophica, vol. I. (henceforth: SL), St. Bonaventure, N.Y., 1974. p.124. Cf.: "Et si dicas: nomina communia, puta talia `homo', `animal' et huiusmodi, significant aliquas res substantiales et non significant substantias singulares, quia tunc `homo' significaret omnes homines, quod videtur falsum, igitur talia nomina significant aliquas substantias praeter substantias signulares: dicendum est quod talia nomina significant praecise res singulares. Unde hoc nomen `homo' nullam rem significat nisi illam quae est homo singularis, et ideo nunquam supponit pro substantia nisi quando supponit pro homine particulari. Et ideo concedendum est quod hoc nomen `homo' aeque primo significat omnes homines particulares ... " SL p.60. Cf. also: "Hic primo notandum est quod non intendit Philosophus quod voces omnes proprie et primo significant passiones animae, quasi sint impositae ad significandum principaliter passiones animae. Sed multae voces et nomina primae intentionis sunt impositae ad significandum primo res, sicut haec vox `homo' imponitur primo ad significandum omnes homines ..." Ockham: Expositio in Librum Perihermeneias Aristotelis, eds. A. Gambatese-S. Brown, Opera Philosophica, vol. II., St. Bonaventure N.Y., 1978., p.347.

[24] "Whether or not Ockham's criteria of primary and secondary signification are adequate, his predecessors and contemporaries thought that Ockham had the priorities exactly reversed." M. McCord Adams: William Ockham, Notre Dame, 1987, Vol.I. p.325. For a detailed discussion of the niceties connected to earlier views see Sten Ebbesen: "Concrete Accidental Terms: Late Thirteen-Century Debates About Problems Relating to Such Terms as `Album'", in: N. Kretzmann (ed.): Meaning and Inference in Mediaeval Philosophy, Kluwer Academic Publishers, 1989. See also the related papers by R. Andrews and R. Huelsen in the same volume.

[25] Whether these whitenesses are actual or not. The term `white' will supposit, however, in a proposition with a present tense copula only for those of its significata whose whitenesses are actual. See e.g. SL p. 95. Cf. Walter Burleigh: De Puritate Artis Logicae Tractatus Longior with a revised edition of the Tractatus Brevior, (ed. Ph. Boehner) St. Bonaventure, N.Y., 1955, c.3. p.9. ll.6-16.

[26] See e.g. SL, pp.37-38.

[27] Cf. e.g. Guillelmi de Ockham: Quodlibeta Septem (henceforth Quodl.), ed. J.C.Wey, Opera Theologica, vol.IX., St. Bonaventure N.Y., 1980. V.25, VI.20-25.

[28] Cf. e.g. SL, cc.50-54.

[29] A theologically more intriguing question of this kind was whether Christ's being the son of both the Holy Mother and the Heavenly Father multiplies his filiations. See e.g. St. Thomas Aquinas, ST III, q.35.a.5.

[30] See SL Pars I. cc.5-9. pp.16-34; Quodl. V. qq.9-11.

[31] See Buridanus: Kommentar zur Aristotelischen Metaphysik, Minerva G.M.B.H. Frankfurt a.M., 1964, lb.5.q.9. Utrum sit aliqua relatio preter animam distincta a suo fundamento.

[32] Cf. Quodl. VI.q.25.pp.681-682: "abstracta relationum non supponunt nisi pro pluribus rebus absolutis coniunctim, sicut nomen collectivum, puta `populus', `exercitus', `turba', `societas'. ... sicut conceditur quod Ioannes est socialis et ista negatur `Ioannes est societas', ita est concedendum quod Sortes est similis, Sortes est aequalis, sed ista negatur `Sortes est similitudo', `Sortes est aequalitas', ista tamen conceditur `Sortes et Plato sunt aequalitas', `duo alba sunt similitudo'. Et ita in omnibus esset dicendum quod talia nomina abstracta relationum sunt nomina collectiva."

[33] Here I follow what can be regarded as the received view on Ockham's connotative concepts. This view, however, was recently severely criticised by Claude Panaccio in his "Connotative Terms in Ockham's Mental Language", Cahiers d'épistémologie, Université du Québec à Montréal, Cahier no 9016, 1990, pp. 1-22. In this paper Panaccio argues that Ockham could consistently endorse the existence of simple connotative concepts, not admitting, though, that a simple connotative term is synonymous with its nominal definition. It is an open question, however, whether Ockham can consistently maintain this latter position. It may well be the case that on the basis of his general semantic principles Ockham is after all committed to holding that nominal definitions are synonymous with their definita, being subordinated to the same concepts. But this would need further inquiry. In any case, from the point of view of its import on the attitude towards ontological questions, it is enough if Ockham's treatment of connotative terms merely gave the impression (whether falsely or not) of what the received interpretation suggests. We may also add that Buridan, while endorsing the existence of simple connotative concepts, treated nominal definitions in the above-described way, not claiming, however, that all connotative terms have nominal definitions. Cf. n.34. below.

[34] For Ockham's treatment of the term `caecus' in this spirit see SL pp.101-103. The presentation of the actual construction would unfortunately involve technicalities that would be quite out of place in this paper. The job will be done in my paper under preparation: Latin as a Formal Language: A Buridanian Semantics, attempting a full reconstruction of Buridan's basic semantic ideas in the framework of a complete formal semantic system. For suggestions in this direction see my "The Changing Role of Entia Rationis in Mediaeval Semantics and Ontology: A Comparative Study with a Reconstruction", to appear in Synthese, 1991. and "`Debeo tibi equum': A Reconstruction of the Theoretical Framework of Buridan's Treatment of the Sophisma", to appear in: S. Read (ed.): Acts of the Ninth European Symposium for Mediaeval Logic and Semantics.

[35] Cf.: "Comme on le sait, Occam pense qu'il est toujours possible de donner une definitio quid nominis des termes connotatifs (SL III-2, 28. p.556. III-3, 26. pp.689-691.) La position de Buridan est différente. ... Buridan réserve explicitement la definitio exprimens quid nominis aux termes vocaux simples auxquels corresponde un terme mental complexe. (Soph. I. concl.11.; Summulae VIII, 2, f. 100ra.) Le problème de savoir si `res alba' et `nasus cavus' sont les orationes dicentes quid nominis respectivement de `album' et de `simum' s'étant posé, Buridan répond conditionaliter: si à `album' correspond dans la pensée un concept complexe, `res alba' sera sa definitio dicens quid nominis (il en est de même pour `simum' et `nasus cavus'); si au contraire, à `album' et à `simum' `correspondent in mente conceptus incomplexi quibus confuse et indistincte substantiam et albedinem, vel nasum et simitatem concipimus, et non substantiam uno conceptu et albedinem alio, nec nasum uno conceptu et simitatem alio, tunc istae definitiones non sunt dicentes quid nominis sed quid rei'. (Summulae VIII.2. 102va; cf. Meta VII, 5.)" A. Maierù: "Significatio et Connotatio chez Buridan", in: J. Pinborg (ed.): The Logic of John Buridan, Copenhagen, 1976. pp.110-111. For the niceties of the differences between Ockham's and Buridan's ontological views see C. Normore: "Buridan's Ontology", in: J. Bogen-J.E. McGuire: How Things Are, D. Reidel Publishing Company, Dordrecht, Holland, 1985.

[36] Cf.: "... Non enim sequitur: `Signum in actu est, ergo res significata est' quia non entia possunt significari per voces sicut et entia, nisi velimus dicere quod esse quod necessario requiruitur ad significatum non est nisi apud intellectum vel imaginationem." Roger Bacon: De Signis, (ed. K.M. Fredborg-L. Nielsen-J. Pinborg), Traditio, 34(1978), pp.75-136. p.82.

[37] Cf.: "dico quod non sunt talia esse obiectiva, quae non sunt nec possunt esse entia realia; nec est unus parvus mundus alius entium obiectivorum; sed illud quod nulla res est, omnino nihil est ..." Quodl. III.q.4. pp.218-219. Cf. also the discussion of the problem by E. Karger: "Would Ockham Have Shaved Wyman's Beard?", in: H.A.G. Braakhuis-C.H. Kneepkens-L.M. de Rijk (eds.): English Logic and Semantics, Nijmegen, Ingenium Publishers, 1981.

[38] For a formal treatment of quantification over and reference to nonexistents applying the mediaeval idea of ampliation, see "Existence, Quantification and the Mediaeval Theory of Ampliation" in my Ars Artium: Essays in Philosophical Semantics, Mediaeval and Modern, Budapest, 1988. In the system presented there existence is simply denied to any objects of reference that do not actually exist.

[39] Cf.: "Here is a recipe for ontology. First divide the expressions of one's language into those which purport to pick things out and those which don't. Then see whether some of those which purport to pick things out can be defined in terms of others. Finally admit in your ontology whatever an undefinable term purports to pick out. This scheme expresses (though vaguely and incompletely) one of the central intuitions behind many ontological programmes. What is admitted by an ontologist operating within this framework will depend, of course, upon how he or she divides expressions, on what resources of definition are available, and, perhaps, on pressures from other theories." C. Normore: "Buridan's Ontology", in: J. Bogen-J.E. McGuire: How Things Are, D. Reidel Publishing Company, Dordrecht, Holland, 1985. p.189.

[40] For detailed account and ample references see Adams, op. cit. vol. I. part 3, cc.13-14.

[41] I was pleased to learn that John Haldane identified the same kind of paradigm-shift in Ockham's epistemology in his: "Mind/World Identity and the Anti-realist Challenge", forthcoming in: J. Haldane-C. Wright: Realism, Reason and Projection, Oxford University Press, 1991.

[42] For a suggestion concerning the semantics of relative identity, see n.5. of "On Being and Essence in Saint Thomas Aquinas's Metaphysics and Philosophy of Science", in my Ars Artium, also in S. Knuuttila (et. al. eds.): Knowledge and the Sciences in Mediaeval Philosophy: Proceedings of the Eighth International Congress of Mediaeval Philosophy Vol. II., Helsinki, 1990. The idea is that if we adopt the inherence theory of predication and the corresponding theory of signification, then we may say that `a is the same F as b' is true iff SGT(F)(a)=SGT(F)(b), which certainly may hold good even if a and b are numerically distinct entities. (Where on the right-hand side of the equivalence a and b are items of the universe of discourse that the object-language names `a' and `b' refer to.)

[43] Note here that it also follows that CON(m)(T1)(u)=CON(m)(T2)(u) iff SGT(T1)(u)=SGT(T2)(u), for any u, that is two terms signify the same things, i.e., they are synonymous, iff they are subordinated to the same concept. The point is that these follow from our characterisation of concepts by means of model-theoretical functions, and hence from the standard identity conditions for functions. For a detailed formal account see again the Appendix of my "Understanding Matters from a Logical Angle" and "`Socrates est species': Logic, Metaphysics and Psychology in St. Thomas Aquinas' Treatment of a Paralogism", in: G. Klima: Ars Artium: Essays in Philosophical Semantics, Mediaeval and Modern, Budapest, 1988, also to appear in K. Jacobi (ed.): Acts of the 8th European Symposium of Mediaeval Logic and Semantics, Munich, Philosophia Verlag, 1990.

[44] Indeed, the conclusion of this view of concepts, that qualities of the mind that are concepts are only contingently concepts, i.e. qualities that represent external objects to a mind, is explicitly stated by Pierre d'Ailly: "illa qualitas que est conceptus, licet naturaliter sit conceptus, non tamen necessario est conceptus, quare conceptus potest non esse conceptus". See Pierre d'Ailly: Conceptus, text edited in: L. Kaczmarek: Modi Significandi und Ihre Destruktionen, Munster, 1980, (contaning editions of Pierre d'Ailly: Destructiones Modorum Significandi and Conceptus), p.92. Cf. also pp.82. and 91-92.

[45] "... Omnis res absoluta distincta loco et subiecto ab alia re absoluta potest per divinam potentiam existere alia re absoluta destructa. Sed visio intuitiva tam sensitiva quam intellectiva est res absoluta distincta loco et subiecto ab obiecto viso, sicut si videam intuitive stellam existentem in celo, ista visio intuitiva, sive sit sensitiva sive intellectiva, distinguitur loco et subiecto ab obiecto viso. Ergo ista visio potest manere stella destructa." A. Pelzer: "Les 51 articles de Guillaume Occam censurés, en Avignon, en 1326", Revue d'histoire ecclésiastique, 1922, pp.240-70. Quoted by E.A. Moody: "Ockham, Buridan, and Nicholas of Autrecourt", in: Studies in Medieval Philosophy, Science and Logic, UC Press, Berkeley-LA-London, 1975. p.134.

[46 ]"Sed forsan dicetis, prout mihi videtur, volebatis innuere in quadam disputatione apud Predicatores, quod, licet ex visione non possit inferri obiectum visum esse, quando visio ponitur in esse a causa supernaturali vel conservatur ab ipsa, tamen quando posita est in esse a causis naturalibus precise, concurrente influentia generali primi agentis, tunc potest inferri. Contra. Quando ex aliquo antecedente, si esset positum ab aliquo agente, non poterit inferri consequentia formali et evidenti aliquod consequens: nec ex illo antecedente poterit inferri illud consequens, a quocunque fuerit positum in esse." ibid. p.135.

[47] Two outstanding examples are Moody and Adams in their opp. cit.

[48] "Et patet quod impossibile est rem communem pluribus rebus extra habere illud esse secundum, nisi tantum dum fuerit in anima secundum esse spirituale vel intentionale in suo signo. Et sic intelliguntur quotquot dicta Commentatoris et philosophorum loquentium de ista materia. Metaphysici tamen sciunt quod natura communis prius naturaliter intelligitur a Deo ut communicata multis suppositis quam in effectu communicatur eisdem. Et sic universalitas vel veritas metaphysica non dependet ab intellectu creato, cum praecedit ipsum, sed dependet ab intellectu increato. Quae - ex aeterna notitia intellectuali - producit omnia in effectu! Et ignorantia huius sensus fecit Ockham et multos alios doctores signorum ex infirmitate intellectus declinare ab universali reali." John Wyclif: Tractatus de Universalibus, (ed. I.J. Mueller), Clarendon Press, Oxford, 1985. c.2. p.65.

[49] No wonder Buridan, the great systematiser and developer of Ockham's doctrine of concepts, in his refutations of Nicholas of Autrecourt's scepticism, resorted to the notion of ex suppositione necessity and to a probabilistic interpretation of certainty in natural science. Cf. Moody, op. cit.

[50] C. Wright: "On Putnam's Proof That We Are Not Brains-In-A-Vat", for the Gifford Conference on the philosophy of Hilary Putnam, held at St. Andrews Nov.23-26, 1990. draft, p.21. I owe thanks to Crispin Wright for his kindly supplying me with a copy of this particularly inspiring paper even before its final completion.

[51] Note here that by calling this the "older model" I by no means wish to imply that the other model, what I called "the efficient causality model", was entirely Ockham's invention. In fact, I suspect that what partly motivated Plato's introduction of what I called "the formal causality model" was the scepticism of Protagoras and other sophists, formulated in an efficient causality framework. But the details of this ancient story are beyond the scope of this paper.

[52] This paper was written during my stay in St. Andrews, Scotland, as Gifford Visiting Fellow of the Department of Logic and Metaphysics of the University of St. Andrews in the second half of 1990. An earlier version was presented and discussed there at a meeting of the Philosophy Club, followed by further inspiring discussions with John Haldane and Stephen Read. I would like to thank the University of St. Andrews for the wonderful time we spent there with my family, for the kindness and hospitality we received from everyone we met during our whole visit. I owe special thanks, however, to Stephen Read, chairman of the Department, for having arranged this visit in the first place, for the fruitful scholarly discussions and for kindly correcting whatever I committed in my paper against the English language.