Aquinas wrote:

Being is not a genus, since it is not predicated univocally, but analogically

Genus is a term that is used in Aristotles Organon; as is predicate and I think univocal and analogy.

If ordinary language is a guide, then one would expect two terms in analogy: ie A is analogous to B; but this is not the case above - why? One might to expect one or the other term is left implicit, perhaps.

Univocal translated literally means 'one voice'.

Predicate, is that part of a sentence that 'acts' or completes an idea or proposition for some subject.

Genus, if zoology is any guide, is a grouping of individuals that have some essential character in common.

So, the above sentence seems to say that Being is not something that all beings have in common; since there is not a single predicate that can be said for all subjects in an essential way; but we have many predicates (possibly infinite) each of whose subjects form a genus; and thus we have many (possibly infinite) genuses of being.

And to reduce all these genuses of being to a single genus is not possible via some predicate (since none of these genuses have an essence in common); so to 'produce' or 'find' Being one must use analogy.

Is this the correct sense of the sentence above in Thomism?

  • 1
    Can someone add 'Thomism' as a tag; I can't from a smartphone. Thxs. Commented Jul 12, 2015 at 10:45
  • That would make the tree of life not a tree.
    – Joshua
    Commented Mar 26 at 19:28
  • @Joshua: The tree of life is not actually tree you can find in the countryside ... Commented Mar 29 at 6:19
  • Correction: That would make the tree of life a directed graph instead of a tree.
    – Joshua
    Commented Mar 29 at 15:06

2 Answers 2


Your analysis seems to me quite correct. The talk about the "analogical" predication of being may hint at the analogies among the four distinct modes of being that are distinguished in Aristotle's Metaphysics: essential being, accidental being, potential being, and being-true (logical being).

It is probably worth pointing out that "being is not a genus" was already part of Aristotle's doctrine, and not an innovation of Aquinas'.

Now one of the conclusions we reached on substance and being was that none of the universals can be a substance. And, presumably, being cannot itself be a substance as a single thing set apart from the many – it must surely be something common to them, must therefore be no more than something that is predicated of them . . . unity cannot be a genus, and for the same reasons that being . . . cannot be either. (Metaphysics Iota 2)

Aquinas upheld Aristotle's doctrine that being is not a genus; even though Aquinas' concept of being was somewhat "thicker" than that of Aristotle's. Aristotle held that individuals are composed of matter and form. Some later Aristotelian philosophers, Aquinas among them, came to hold that apart from form and matter, an individual is constituted by a distinct "act of being", and that it was that act of being which held the matter and form together. This made Aquinas' concept of being more substantial than that of Aristotle's. Still, being was still held as not a genus.


From reading the paragraph after, it seems that Zoology is not a good guide here for being. Based on the line you quoted, a genus specifically refers to something that "predicates univocally." When something "is predicated univocally," there's an "IS A" relationship between the things of which it is predicated:

That is predicated univocally which is predicated according to the same word and according to the same meaning, or definition, as "animal" is predicated of man and of ass." For each is said to be an animal, and each is an animated substance capable of sensing, which is the definition of animal.

Thomas says being is predicated analogically, which he goes on to define

That is said to be predicated analogically which is predicated of many things so that the meaning is different for each, but so that there is an attribution to some one and the same thing, as "healthy" is said of the body of an animal and of urine and of a drink, but does not mean wholly the same thing with respect to all of them. For it is said of urine as of a sign of health, of the body as of the subject of health, and of the drink as of a cause of health. Nonetheless all of these meanings include an attribution to one end, namely health.

So, when you say "Being is not something that all beings have in common," it doesn't seem to be the right interpretation - things that predicate being have different meaning for how that predication happens. This is in contrast to a genus, "man" and "dog" are both animals in the same way, but Socrates's being is different than mine, which is in turn different than Virtue or Atlantis - all 4 objects predicate being, but in a different sense (Socrates historically; myself physically; Virtue abstractly; Atlantis through imagination).

  • Just to clarify, I was using Zoology for a description of Genus, not Being; as I'm not clear on its philosophical definition. Commented Jul 13, 2015 at 22:51

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