A distinction, first drawn by C.S.Peirce, between signs considered as abstract things, "types," or as particular instances in use, "tokens." Thus, for example, the number of words (tokens) in a book—the total "word-count" of its content—may be quite large, but the number of different words, each considered as a "type" it uses—the working vocabulary of its author—is usualy much smaller.

    The distinction is  used by Davidson and other philosophers of mind to emphasize that a reasonable identity theory need only argue for the identity of mental and physical events as types, not necessarily as tokens.