 whose rules permit inferring anything from anything, decisively refutes the idea that the senses of logical constants are fixed by their introduction and/or elimination rules. But although Prior’s example (anticipated in Popper 1946–7, 284) certainly shows that not all sets of introduction and elimination rules determine a coherent meaning for a logical constant, it does not show that none do, or that the logical constants are not distinctive in having their meanings determined in this way. For some attempts to articulate conditions under which introduction and elimination rules do fix a meaning, see Belnap (1962), Hacking (1979, 296–8), Kremer (1988, 62–6), and Hodes (2004, 156–7).