The general conflict between Aquinas and the Latin Averroists

This conflict concerns handling any sort of perceived contradiction between faith and reason, that is, theology and philosophy.

Examples are:

1. The "eternity" of the world

2. The unity of the intellect

3. The miracle of the Holy Eucharist

Siger’s position:

Such conflicts emerge on account of using valid principles and valid reasonings to conclusions which genuinely contradict each other. There is no solution of the contradiction. Therefore, a Christian philosopher, insofar as a philosopher, has to adhere to the philosophical conclusion, but insofar as a Christian, he has to admit that the truths of faith have absolute epistemic priority.

Tempier’s "position":

Philosophy endangers faith, therefore, it has to be abolished.

Aquinas’ position:

Such conflicts emerge on account of some abuse of reason, some fallacious reasoning or some misinterpretation of the principles. The conflicts always are, and have to be, merely apparent, and thus the conflicts can always be solved, by the use of reason.

The particular conflict between Aquinas and Siger concerning the unity of the human intellect

The following three propositions are apparently inconsistent:

1. The principle of individuation is matter

2. The human intellect is immaterial

3. There are as many human intellects as there are humans

The inconsistency can be made more explicit in terms of the following interpretations of 1-3:

1. Several individuals of the same species are distinct from one another if and only if they have distinct parcels of designated matter

2. The human intellect has no matter whatsoever

3. There are several human intellects (i.e., several intellects that belong to the same species)

On account of the inconsistency, Siger opted for Averroes’ solution, and denied (3), by stating that there is only one human intellect, shared by all humans, united with them only in its operation, namely, thinking. But this position conflicts with the Christian faith in personal immortality and individual reward and punishment in the afterlife.

Aquinas’s solution is providing a different interpretation of 2.

Scotus’ solution involves the denial of 1 in the first place. (His radically different theory of individuation is designed to avoid not only this particular inconsistency, but a number of further, ontological, theological and epistemological problems stemming from the conception expressed by 1.)

Aquinas’s thesis:

Sense perception is the function of a bodily organ, while understanding is not the function of a bodily organ

Proof:

1. A cognitive faculty represents individuals qua individuals as a result of the natural causality of these individuals iff it represents their principle of individuation [self-evident]

2. The principle of individuation is designated matter [from Aquinas’s De Ente et Essentia, c.3. & passim]

3. Therefore, a cognitive faculty represents individuals qua individuals as a result of the natural causality of these individuals iff it represents their designated matter [from 1 & 2]

4. Designated matter is matter contained under particular dimensions, here and now [from Aquinas’s De Ente et Essentia, c. 3. & passim]

5. Therefore, a cognitive faculty represents individuals qua individuals as a result of the natural causality of these individuals iff it represents their matter contained under their particular dimensions, here and now [from 3 & 4]

6. Dimensions here and now are common, per se sensibilia.*

7. Common, per se sensibilia can be represented as a result of the natural causality of the things having them only by the corresponding spatio-temporal properties of what represents them. [from Aquinas’s commentary on the De Anima bk. 2, lc. 12 and 13.]

8. Therefore, a cognitive faculty represents individuals qua individuals as a result of the natural causality of these individuals iff it represents their matter contained under their particular dimensions, here and now, by its own corresponding spatio-temporal properties [from 5 & 6 & 7]

9. Any cognitive faculty that has its own spatio-temporal properties is material [self-evident]

10. Therefore, any cognitive faculty represents individuals qua individuals iff it is material [from 8 & 9]

11. Any sense is a cognitive faculty that represents individuals qua individuals [self-evident]

12. Therefore, any sense is material [from 10 & 11]

13. The human intellect is a cognitive faculty that does not represent individuals qua individuals, but represents individuals in a universal manner [from Aquinas’s explanations of the theory of abstraction, e.g., in ST1 q.85, a. 1.]

14. Therefore, the human intellect is immaterial [from 13 & 10]

* Per se sensibilia are sensible qualities which, as such, can directly affect one or more senses. Per accidens sensibilia are other sensible qualities, which are joined in the object to its per se sensible qualities. (Sugar cube: white, sweet, cubical, sugar.) Proper sensibilia are per se sensibilia which, as such, can directly affect only one of the senses. Common sensibilia are per se sensibilia which directly affect any and all of the senses. This is because common sensibilia are the necessary spatio-temporal determinations of all proper sensibilia. These determinations can be represented only by the corresponding determinations of the representing act; thus it also has to be material.

Aquinas’s theological problem

Singularity is apparently incompatible with direct intelligibility. The cognition of singulars as such is dependent on their being materially represented in the phantasms of the sensory apparatus of the body. The intellect always has to turn to these phantasms [conversio ad phantasmata] to have some cognition of a singular as distinct from another of the same species.

But then, how can the separate soul have any cognition of singulars (let alone angels and God)?

Scotus’s alternative

The principle of individuation of a substance cannot be an accident, for the individuation of an accident is itself dependent on the individual substance in which it inheres

But quantity, which designates designated matter is an accident

Therefore, designated matter cannot be the principle of individuation

Thus, the principle of individuation has to be some per se individual, substantial, formal principle.

Hence, the principle of individuation is haecceity [this-ness]

1. Haecceity is the ultimate individual, formal difference, which distinguishes individuals of the same species

2. It is the ultimate realization of an individual’s nature

3. It is merely formally distinct from the individual’s specific and generic substantial forms

4. Thus, these forms are intellectually abstractible from haecceity, but it can never get really separated from them

But since haecceity is a formal principle, its being represented by the intellect is not incompatible with the intellect’s immateriality, as Thomas assumed regarding his principle of individuation. Therefore, the human intellect can have a vague intuitive cognition of singulars (as opposed to its abstractive cognition of universals), even if it cannot have a direct, distinct intuition of their singularity, without turning to the phantasms. But this much is enough for it to have intellectual memory of the singulars, which solves the theological problem.