Key Arguments

• He defines affirmation and denial as inherently predicative, and ties them directly to truth and falsity: 'An affirmation, however, is something [predicated] of something, as too is a denial, and each one is either true or false. 377', so any such act is a composition or separation of subject and predicate with a determinate truth value.
• He expressly contrasts this with understanding in general: 'By contrast, not all understanding is such, but that of the what-it-is in the sense of the essence is true, and is not something [predicated] of something.', distinguishing a kind of intellection (grasp of essence) that is not a predication and is invariably true.
• He draws an analogy to perception to clarify the point: 'However, just as the seeing of a special object is true, but seeing that the pale is a human or not is not always true, so it is also with [understanding]', where 'seeing of a special object' (e.g., seeing pale) is infallible regarding its proper sensible, but the further judgement 'the pale is a human' can be mistaken; similarly, intellection of essence is infallible, while composite judgements can err.
• This supports his broader thesis in III.6 that falsehood requires combination or separation, whereas simple, non‑composite cognitions—whether in perception (proper sensibles) or in intellect (essences)—are always true.

Source Quotes

375 And if to something there is not a contrary of its causes, it knows itself and is an activity | 430 b 25 | and separable. 376 An affirmation, however, is something [predicated] of something, as too is a denial, and each one is either true or false. 377 By contrast, not all understanding is such, but that of the what-it-is in the sense of the essence is true, and is not something [predicated] of something. However, just as the seeing of a special object is true, but seeing that the pale is a human or not is not always true, so it is also with [understanding]

376 An affirmation, however, is something [predicated] of something, as too is a denial, and each one is either true or false. 377 By contrast, not all understanding is such, but that of the what-it-is in the sense of the essence is true, and is not something [predicated] of something. However, just as the seeing of a special object is true, but seeing that the pale is a human or not is not always true, so it is also with [understanding]

377 By contrast, not all understanding is such, but that of the what-it-is in the sense of the essence is true, and is not something [predicated] of something. However, just as the seeing of a special object is true, but seeing that the pale is a human or not is not always true, so it is also with [understanding]

Key Concepts

• An affirmation, however, is something [predicated] of something, as too is a denial, and each one is either true or false. 377
• By contrast, not all understanding is such, but that of the what-it-is in the sense of the essence is true, and is not something [predicated] of something.
• However, just as the seeing of a special object is true, but seeing that the pale is a human or not is not always true, so it is also with [understanding]

Context

Final sentences of III.6 (430b25ff.), where Aristotle completes his analysis of truth, falsehood, and indivisible objects by distinguishing propositional affirmation/denial from the non‑predicative, always‑true understanding of essences, using an analogy with seeing proper sensibles versus making further classificatory judgements.