Here is the general schema for a real definition:
- S ise an F.
(Side-note: In some contexts is this a schema for reduction too? Interesting...)
Real definitions are 'fine-grained'. You cannot always substitute extensional equivalents into the predicate position to get the same truth value. For instance, suppose all and only the actually existing rational animals are animals which evolved by a certain evolutionary process P on earth. Even if this so, the following is not true:
- Man ise an animal which evolved by process P on earth.
So real definitions are fine-grained. In fact, real definitions are very fine-grained; you cannot even substitute intensional equivalents into the predicate position and always retain the same truth value. Suppose for instance that, necessarily, any animal which is rational is the type of thing which can speak a language. This actually seems pretty plausible. (If not, think of some other necessary consequence of being rational. You could even use some fancy disjunctive, conjunctive, or conditional properties, though I try to avoid these.) Even if this is so, the following is not true:
- Man ise an language-capable animal.
So, the predicate position in real definitions is a hyperintensional position, in the sense that substitution of intensional equivalents will not always preserve the same truth value. I take it these points cohere well with what has been said about real definition and essence up to now by others, such as Fine.
In the next post, I'll try to say something about how the hyperintensionality in real definitions means that counterpossibles will be very closely related to real definitions. Maybe this will help, at least a little, with the epistemology of essence.
Lately I have been suspecting that hyperintensionality, counterpossibles, essence, explanation, grounding, reduction, fundamentality, naturalness, intrinsicality, and lots of other things are very closely related. In the future I'd like to try to bring out some of these relationships. I'm not sure how successful this will be, but my metaphysical nose is leading me in this direction.
2 comments:
Hi Alfredo. Where do you get the idea that essence is *the truthmaker* of a real definition from? Anyone in the literature who holds this view? I like it... But, potential problems might carry over from the problems that plague truthmaker theory. E.g. the general need to posit an existent thing for every truth which leads to all the usual counterexamples. Consider an analogous problem for the truthmaker account of essence: Holes have a real definition. (Presumably, something like 'a hole is a definite-shaped absence in a material object' - or whatever). But what is the truthmaker for that? It needs to be an existent thing. But there better not be anything 'existent' about holes. But the essence of holes ought to be closely tied up with holes. This seems a problem. - Br Reginald
Hello Br Reginald!
I'm not sure if anyone says this in the literature or not (probably; "there is nothing so absurd but some philosopher has said it"). But I take it to be just a more precise way of stating what an essence is. A more loose way of characterizing essence is as that in virtue of which something "is what it is." Surely it seems this must be the same as what makes something's real definition hold true of it. (Now that I think about it, maybe I could even be more precise in stating this idea and making sure my statement is sufficiently "de re.")
As for the worries: I'm not sure that by defining essence this way I'm committed to a whole truthmaker "theory of truth". In fact, my definition is, strictly speaking, consistent with the idea that only, say, fifty-thousand of the truths have truthmakers while the rest do not! This is preposterous of course, but it's open, logically speaking, to the view I advance. I only need to be granted that *some* truths have truthmakers. So any worries that plague truthmaker theories of truth in general need not apply to me (though, in fact, I am sympathetic to truthmaker theories).
Regarding holes: You could question, among other things, whether holes do or do not have a real definition (after all, *assuming* they don't exist, they are not in the categories either of substance or accident), whether they do or do not in fact exist, whether things which exist in a lesser sense than substances (maybe even not at all) can or cannot have real definitions, and whether some negative truths or truths about non-beings *do* in fact have truthmakers. I think at least some of these questions might give answers that deal with the worry, though different people might disagree about which ones they are.
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