Philosophers often describe one thing as consisting in some other things. However, I've never seen a rigorous definition of the 'consists in' relation. Does such a definition exist?

  • You can find some hints in Object. – Mauro ALLEGRANZA Apr 9 '15 at 13:09
  • Could you give an example? – Ram Tobolski Apr 9 '15 at 14:13
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    You can see also Mereology : "the theory of parthood relations: of the relations of part to whole and the relations of part to part within a whole". – Mauro ALLEGRANZA Apr 9 '15 at 16:33
  • @RamTobolski A search on Google for "consists in" philosophy will render examples unaffected by my misbeliefs about the relation. Nevertheless, I think that we may use the phrase consists in thus: "Persistence of personal identity consists in psychological continuity."; "Purple consists in blue and red"; "Causation consists in the interaction of forces." – Hal Apr 9 '15 at 20:57
  • @MauroALLEGRANZA You regard the relation as one between wholes and parts? Unless we regard perspectival, and conceptual, things as parts, then it would seem to me that that the set of relations between parts and wholes just includes the relations denoted by comprises and constitutes; is a part of and the whole of; as well as, perhaps, emerges out of and, I suppose, immerges into. However, I defer to your expertise. – Hal Apr 9 '15 at 21:27

Apocrypha has it that Quine used to demand he be given the collected whole comprised of the parts of a chicken (i.e. what a chicken consists in). Given the normal thing, a slaughtered and partitioned chicken, he would complain that it was not a collected whole. Given a live chicken he would complain that these were not the parts of a chicken, this was a chicken. (Presumably given a dead chicken, he would claim this was not even a chicken, it was the corpse of a chicken.)

It is impossible to produce what the chicken consists in, without including all the things beyond that that the chicken consist of. If you have any real object, and it is not a chicken, you do not really have everything that a chicken consists in. But a real chicken contains the incidental aspects of the chicken, in addition to the aspects that really make it a chicken, so a real chicken is not what a chicken consists in either.

Various logicians, including Quine himself have tried to make sense of this idea, going back beyond Parmenides and Socrates (in Plato's dialog named after the former) discussing whether a hand is one thing or many things. Is it really made up of the fingers or are they just incidental aspects of it?

To me the entire issue is an overestimation of our power to define things with a single notion. We assume that there is some (extraordinarily complex) statement that would perfectly capture chickenhood or hand-ness. But we are wrong, the definition of a chicken, or a hand, is a convention arrived at by iteration and approximation.

The notion of something consisting in its principal aspects is itself a weak approximation to how meaning works. The statement itself never means anything without example, refinement or reframing. So there is no room here for a rigorous definition.


I think that "consist" expresses actually just the identity relation in disguise. For example, saying "being human consists in being a rational animal" is equivalent to the equality "being human = being a rational animal" or "humanity = rationality + animality".

The "consist" word is used in the context of locating the relevant property among other properties. For example, one considers many particular human beings. Some are short, some tall, some bald, some hairy, etc. And one wonders, where is the humanity in all these humans? And then one is told: "being human consists in being a rational animal". Then one knows better where to look, what to focus on, how to isolate the humanity within the multiplicity of human beings and their many properties.

  • Consist does express an identity relation, but it comes in two flavors. Consists of means something normal and pedestrian, but consists in presumes some notion of 'essentiality' that is never articulated well. One can say a human consists of cells, without further clarification. But one always needs to follow up an assertion of X consists in Y with a clarification as to what kind of 'essence' is being supposed. – user9166 Apr 13 '15 at 15:33
  • @jober I agree that the notion "essence" is related here. I preferred to bypass the obscurity of "essence" by sticking to the clearer case of identify. – Ram Tobolski Apr 13 '15 at 16:38
  • But the point is that 'consists in' is not the identity relation, it is the identity relation modulo some notion of essence. Whether you dodge using the word or not, you are talking about the same thing. If you discard he notion of 'essence', the concept falls apart, and can only be used metaphorically. – user9166 Apr 13 '15 at 16:44
  • @jober It is difficult to say if there is a problem at all, without some specific examples. I did ask the OP for examples, but did not get them. – Ram Tobolski Apr 13 '15 at 16:49
  • He wrote back -- Nevertheless, I think that we may use the phrase consists in thus: "Persistence of personal identity consists in psychological continuity."; "Purple consists in blue and red"; "Causation consists in the interaction of forces. -- (I object to the last of these as inappropriate usage, and give the EL&U stackexchange post) Not what you meant by examples? – user9166 Apr 13 '15 at 16:54

Suppose S = {1, 2, 3}.

We could say that S consists of the objects 1, 2 and 3.

Usually, however, this would be stated in set theory as:

For all x, x is in S if and only if x=1 or x=2 or x=3.

  • I don't think that the consists-in relation is the equality relation. Well suppose we say that 'Purple consists in red and blue'. I don't think that that means 'Purple equals the set that just includes red and blue'. Another example would be the claim that 'Personal identity consists in psychological continuity'. – Hal Apr 12 '15 at 18:56

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