Wittgenstein, in his discussion of games (specifically, his idea that concepts are delineated by fuzzy "family resemblance", rather than necessary and sufficient membership criteria) basically makes the same points as Eliezer does in these posts.

Representative quotes:

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! -- ...

And the result of this examination is: we see a complicated network of similarities overlapping and criss-crossing: sometimes overall similarities.

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...

"All right: the concept of number is defined for you as the logical sum of these individual interrelated concepts: cardinal numbers, rational numbers, real numbers, etc.; and in the same way the concept of a game as the logical sum of a corresponding set of sub-concepts." --It need not be so. For I can give the concept 'number' rigid limits in this way, that is, use the word "number" for a rigidly limited concept, but I can also use it so that the extension of the concept is not closed by a frontier. And this is how we do use the word "game". For how is the concept of a game bounded?