I will make it clear beforehand, that the little bit I know about Aristotle is from Aquinas (secondary material) and Deleuze (Difference and Repetition), so there may be some misunderstandings on my part.

Anyway, the reason why Aristotle cannot say that Being is the uppermost genera (above all the categories) is because of the difference. Basically an animal can be rational or winged - but substance is only the animal, man or a bat. However, there's difference (rational or winged) which is still a Being but doesn't fall into the categories. However, isn't rational or winged just Quality?

  • Aristotle can not say that there is a single highest genus (being or any other) because it would have to be differentiated by something that falls outside of it, and hence not be the highest. But since he has ten highest genera what exactly precludes rational and winged from falling under one of them, say quality?
    – Conifold
    Aug 26, 2020 at 12:37

1 Answer 1


isn't rational or winged [specific differences] just Quality?

You seem to be arguing for or implicitly assuming monism*, as though there were only one substance called "being" and the differences between substances really accidental or illusory.

Quality is an accident, but specific differences (differentiæ) pertain to substance and essence.
cf. this chart of categories

St. Thomas Aquinas distinguishes substantial or essential differences from accidental differences, showing that the former is known by the latter, as cause is known by its effect:

De Ente et Essentia, cap. 4:

For even in the case of sensible things, the essential differences themselves are not known; whence they are signified through accidental differences which rise out of the essential ones, as a cause is signified through its effect
In rebus enim sensibilibus etiam ipsæ differentiæ essentiales nobis ignotæ sunt, unde significantur per differentias accidentales, quæ ex essentialibus oriuntur, sicut causa significatur per suum effectuum

cf. the other quotes in this answer to the question "We know substances by means of their accidents?", which discuss differentiæ.

*Monism is false because change exists, pace Parmenides; cf. Part II of Essence & Topicality of Thomism.

  • I was making a point that specific differences (accidents if you will) are nothing but particulars of Quality. They do pertain to substances - the primary category to which all other categories are said of (there is a difference in Sense).The problem Deleuze is tackling here though, was there is no concrete knowledge here (Hegel says something similar) when it comes to particulars. Isnt "essence" of a substance not just assumed here implicitly? Aug 25, 2020 at 17:58
  • @RajanAggarwal "there is no concrete [do you mean scientific?] knowledge here […] when it comes to particulars" That's true; "our intellect knows directly the universal only" (Whether our intellect knows singulars?).
    – Geremia
    Aug 25, 2020 at 18:32
  • @RajanAggarwal "Isnt 'essence' of a substance not just assumed here implicitly?" Substances are first in the order of being, but sensing accidents comes before in the order of our knowing being. (Similarly, causes exist, even though we know effects first. In the process of discovering causes, we "assume" a cause exists for certain effects, until we've proven those effects show the cause exists.)
    – Geremia
    Aug 25, 2020 at 18:45
  • 1
    @RajanAggarwal "specific differences (accidents if you will)" Specific differences ≠ accidents. Accidents are signs of specific differences. Accidents inhere in a substance by definition. (Accidere means "to fall/come to", in the sense that accidents attach onto a substance.)
    – Geremia
    Aug 25, 2020 at 18:45
  • @RajanAggarwal A really good book related to this topic is Brain Kemple's Ens Primum Cognitum in Thomas Aquinas and the Tradition: The Philosophy of Being as First Known (2017).
    – Geremia
    Aug 25, 2020 at 18:47

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