Different interpretations of materiality in Aquinas

x is material(1):= x is a subsisting substance and has matter as its integral part

x is immaterial(1):= x is a subsisting substance and has no matter as its integral part

Corollary 0: No form is material(1), and subsistent forms are immaterial(1)

x is material(2):= for x to be is for x to inform matter

Note: this definition may express necessity or just actual fact; therefore, we need to distinguish the following two possibilities:

x is material(2a):= for x to be is necessarily for x to inform matter

x is material(2b):= for x to be is actually, but not necessarily, for x to inform matter

Correspondingly,

x is immaterial(2a):= for x to be is necessarily not for x to inform matter

x is immaterial(2b):= for x to be is not actually, and not impossibly for x to inform matter

x is material(3):= x is material(2a), and (i) x is the same as some y in esse intentionale, and (ii) the matter x informs is specifically (though not numerically) the same as the matter y informs

[Note: if we do not allow (i) and (ii) to hold together above, i.e., we do not think that some form x that informs specifically the same matter as another form y can be the same as y in esse intentionale, then nothing is material(3), so every material(2a) form x that is the same as some y in esse intentionale, i.e., that is some encoding of y, is immaterial(3) in accordance with the following definition. In this case, we would take only those forms to be received intentionally in something else that exist in a different kind of matter in that something else; i.e., we would restrict the notion of the intentional reception of forms to merely intentionally received forms, using intentional as an exclusive, rather than a permissive, qualification, not allowing that a form may be received both intentionally and naturally.]

x is immaterial(3):= x is material(2a) and (i) x is the same as some y in esse intentionale, and (ii) the matter x informs is specifically (as well as numerically) distinct from the matter y informs

Corollary 1: if x is immaterial(2a), and x informs something, then what it informs is not material(1) or material(2a) [because if it were, then x would have to inform matter, contrary to the assumption and the definition of ‘material(2a)’], so, it is immaterial(1), and immaterial(2a) or immaterial(2b), but it may be material(2b).

Corollary 2: a form in esse intentionale can be material(2a), yet immaterial(3); hence we have the possibility of the “immaterial reception” of material forms in the material senses

Corollary 3: any form received in esse naturale from another thing of the same kind having specifically the same matter is material(3), and not immaterial(3); but any form received merely intentionally, i.e., in a subject having a specifically different matter from its object, is immaterial(3)

Corollary 4: the human soul is material(2b) when it informs the body, and it is immaterial(2b), when it is separated from the body; but it is neither material(2a), nor immaterial(2a)