Ludwig Wittgenstein famously argued that some concepts apply by virtue of a ‘family resemblance’, rather than a set of necessary and sufficient conditions. A family resemblance concept has an open-ended set of identifying properties, such that a) not all the properties need be instantiated for the concept to apply, and b) the properties do not form an exhaustive list (but may be added or subtracted in different contexts). In Philosophical Investigations, he cites as candidates the concepts ‘language’, ‘game’ and ‘number’:
Instead of producing something common to all that we call language, I am saying that these phenomena have no one thing in common which makes us use the same word for all, – but that they are related to one another in many different ways. And it is because of this relationship, or these relationships, that we call them all “language” (§65).
Consider for example the proceedings that we call “games”. I mean board-games, card-games, ball-games, Olympic games, and so on. What is common to them all? — Don’t say: “There must be something common, or they would not be called ‘games’ ” – but look and see whether there is anything common to all. — For if you look at them you will not see something that is common to all, but similarities, relationships, and a whole series of them at that. To repeat: don’t think, but look! (§66).
I can think of no better expression to characterize these similarities than “family resemblances“; for the various resemblances between members of a family: build, features, colour of eyes, gait, temperament, etc. etc. overlap and cries-cross in the same way. – And I shall say: ‘games’ form a family … And we extend our concept of number as in spinning a thread we twist fibre on fibre. And the strength of the thread does not reside in the fact that some one fibre runs through its whole length, but in the overlapping of many fibres (§67).
‘Family resemblance’ is one of the few technical ideas in philosophy that has successfully crossed over into other disciplines, such as art theory, literary studies, psychology, law and political science; as well as into ‘middle-brow’ discourse generally. By now, the notion is so well-entrenched that hardly anyone would think of questioning its applicability to a wide range of concepts, such as ‘art’, ‘justice’ and ‘mind’ (and some would argue, to all concepts).
The popularity of this approach is understandable. The concepts which are claimed to be of the family resemblance type are often difficult (if not impossible) to define. The family resemblance model does away with the need for a definition, thus obviating a number of thorny philosophical problems; on the grounds that questions such as ‘What is Art?’ or ‘What is Justice?’ are seeking a definition where none is necessary. Family resemblance also offers a simple solution to the Sorites Paradox, as in the question ‘How many grains make a heap?’. If ‘heap’ is a family resemblance concept, then there is no fixed number of grains that make a heap, anymore than there are a fixed number of legs that make a table.
Politics is another reason for widespread acceptance of the family resemblance theory. If any definition of a family resemblance concept is necessarily partial, and therefore selective, then the possibility arises that the selection may be politically weighted. For example, if ‘female’ is a family resemblance term, then it can be argued that definitions of ‘female’ often include traits that serve the purpose of naturalizing and legitimizing patriachy. Feminists can then counter these patriarchal definitions by emphasizing a different set of traits as ‘feminine’, including adding and subtracting traits to change the concept altogether (or even doing away with the concept, in favor of a variety of gender categories as in ‘LGBTQIA’).
The family resemblance paradigm offers a philosophical justification for the strategy of moving semantic goalposts to bolster the position of underprivileged classes, a practice that is the bread-and-butter of critical studies and post-modern thought in general. A third reason for the popularity of the family resemblance idea is its intuitive appeal. After all, even mundane concepts like ‘chair’ defy definition into a set of necessary and sufficient conditions. It seems obvious that no set of such conditions could possibly allow us to pick out all and only chairs, let alone more nebulous objects such as games.
However, there is a major problem with the family resemblance approach. In essence, the problem is that everything resembles everything else, and everything is different from everything else. Proponents of the family resemblance theory would be quick to reply that there are degrees of resemblance; that tables resemble each other more than they do cats, for example.
But where is the evidence that our recognition of these ‘degrees of resemblance’ is logically prior to our understanding the concepts ‘table’ and ‘cat’? In other words, do we group tables together because they resemble each other, or do we view tables as resembling each other because we have already picked out certain relations as being ones of ‘resemblance’ (and ‘difference’) when comparing tables (and contrasting them with other things which we have already categorized in other ways)? After all, cats and tables do resemble each other in many respects, but we don’t usually regard those respects as relevant.
Some may respond by echoing Wittgenstein, “Look! Can’t you just see the resemblances (and differences)?” Oddly enough, this was an approach that Wittgenstein himself criticized in the Investigations, outside his remarks on family resemblance; for example, when he dismissed the argument that criteria for ‘absolute identity’ can be derived from the perfect identity that a thing has with itself.
For identity we seem to have an infallible paradigm: namely, in the identity of a thing with itself. I feel like saying: “Here at any rate, there can’t be different interpretations. If someone sees a thing, he sees identity, too.” Then are two things the same when they are what one thing is? And how am I to apply what the one thing shows me to the case of two things? (§215).
Wittgenstein argued that the inference from everything being identical with itself to the existence of criteria for ‘absolute identity’ is a false move, an empty gesture. In making the move, one is misled by the grammar of the sentence ‘x is identical with itself’, into thinking the sentence is logically equivalent to ‘x is identical to y’ where x and y are two spatio-temporally separate things. The truth of the former statement does not rest on criteria of ‘absolute identity’ by which x is compared with itself, so no such criteria can be carried over to verify the truth of the latter statement. The sentence ‘x is identical with itself’ certainly describes a paradigm case of identity, but offers no formula by which degrees of identity may be measured off from that paradigm.
“A thing is identical with itself.” — There is no finer example of a useless sentence, which nevertheless is connected with a certain play of the imagination. It is as if in our imagination we put a thing into its own shape and saw that it fitted. (§216)
One may be tempted to reply, “Look! Can’t you just see that x is absolutely identical to itself?” The problem lies not in what we see, but in the conclusions drawn from what we see; as in the unwarranted move from a) the observation that things falling under the same concept resemble each other, to b) the conclusion that things fall under the same concept because they resemble each other.
Some supporters of the family resemblance paradigm may reply that even non-human animals, with no capacity for language, seem to be able to identify things by similarity. Surely, this shows that the ability to group objects by similarity is pre-linguistic, and therefore likely proto-linguistic?
This argument from animal behavior is a non-starter, because it takes a human language-user to tell you that a non-language-using non-human animal (or for that matter, a human baby) is ‘grouping things by similarity’. A pig hunting for truffles does not view itself as ‘grouping truffles by similarity of scent’, it is merely acting on instinct. When we say that non-human (non-language-using) animals are ‘picking out objects by similarity’, we are really using the expression anthropomorphically, ascribing the traits of a language-user to a non-language-using creature. Nothing in the behavior of non-language-using non-humans supports the view that self-consciously grouping things by similarity is pre-linguistic, let alone proto-linguistic. It takes language to knowingly ‘group things together by similarity’ or to ascribe the behavior to someone else.
So did similarities and the related ‘grouping behavior’ exist before language, or does the language faculty divide the world into (and identify certain activities as ‘grouping’) things which are ‘similar’ and ‘different’, based on criteria which are not themselves grounded in similarity and difference? It’s a chicken-or-egg question, but appealing to ‘family resemblance’ does not settle the question one way or the other.