“Conceptual analysis” has been the dominant paradigm in English-language philosophy for much of the twentieth century. and remains influential. Traditionally, a conceptual analysis provides necessary and sufficient conditions for the proper application of a concept. For example, Porphyry defined man as a “mortal rational animal”. A little less restrictively, a modern philosopher might just attempt to lay down a few necessary conditions, or a few sufficient ones. Additionally, this conceptual analysis is supposed to be a matter of pure thought – no experiments required. In a common image: it can be done from the armchair. For a great summary and critique of conceptual analysis, see Ahlstrom-Vij’s book review of McGinn.
This has been a terrible wrong turn, in my view. Although some valuable techniques are used along the way – such as finding counterexamples to proposed generalizations – the odds of achieving true conceptual analysis are miniscule. Here I want to sketch some cognitive-psychological evidence for my skepticism, mainly so that I can refer back to it later. In other words, here I’m doing some metaphilosophy which I’ll lean on when I discuss more typical philosophical topics. A lot of my readers may find this boring, in which case by all means skip it, at least until I lean on it later and you question my reasoning. (Notice how I just implied that I have a lot of readers? Clever and subtle, huh?)
Two of the dominant cognitive-psychological models of categorization are exemplar theory and prototype theory. Take the category of “birds” for example. Both theories focus on similarity, but the exemplar theory supposes that some short list of known birds (robins, pigeons, hawks, …) provides the standard, while the prototype theory proposes that the average characteristics of all known birds provides the standard. Both theories imply that some birds (e.g. penguins) are harder to recognize as birds than others (robins). Prototype theory regards category membership not as an all-or-nothing affair, but as more of a web of interlocking categories which overlap. Exemplar theory is less committed to the existence of vague or borderline category membership, but seems at least compatible with the idea that some animals – Archaeopteryx for example – might be borderline cases of birds.
In order to be useful for thought and communication, a category need not have necessary and sufficient conditions for membership, at least not in any usable form. (A long list of features and their weightings – feathers, flight, talons, beak, etc., etc., along with numerical weightings – might work mathematically, but seems psychologically unrealistic, and certainly not discoverable from the armchair.) Instead, a workable category has short distances in similarity-space between members, compared to the distance between the category and other nearby categories. Crucially, this depends on what things happen to populate the world the speakers live in. The reptiles, mammals, and other animals we contrast to birds help make birds a useful category, because the differences between categories are relatively large. Perhaps in a galaxy far away, there is a planet with many birdlike and mammal-like animals that can be lined up in a gradually differing order with no breaks. If there are intelligent beings on that planet, it is a good bet that just one of their concepts encompasses all of those species.
Another way of saying this is: Things are clustered in the (mathematical) space of properties. The “dimensions” of this space are length, mass, number of feathers, flight speed in air, etc. – any property the thinker in question can measure or observe. And the similarity/distance metric in this space is whatever is salient to the perceiver. As members of the same species, we can usually count on each other’s similarity metrics to be largely commensurate with our own. But if we ever communicate with beings on that distant planet I speculated about in the previous paragraph – the planet of the birdmammals – we need to be more circumspect. They might perceive a glaring gap in the birdmammal spectrum that we just can’t see. Clustering is a feature of the external world X cognizer(s) interaction, not of the external world alone. External here refers to what is outside the cognizers — of course, the world as a whole includes them, which is a point philosophers could stand to remember more often.
Another reason to be skeptical about the prospects for conceptual analysis is that competence far outruns explicit reflective knowledge. We can recognize instances of a concept – pictures of cats on the internet for example – far more easily than we can lay down rules by which cats should be recognized, much less to define “cat”. The fact that it took computer programmers decades to achieve Machine Vision systems which can recognize cats (and other categories) with at least as good reliability as humans can, is evidence of how hard it is to construct such rules. And those programmers had computers to do the grunt work of logical and mathematical computation; they didn’t do it from their armchairs. And those programmers still don’t know the rules for recognizing cats – rather, they know the rules for building neural networks and the rules for training neural networks.
Two other philosophy of language related essays I really like: