This paper addresses what I call ‘the constitutive question’ concerning the rules we follow: namely, what determines the standard for a rule's correct application. John McDowell has offered a putative ‘middle position’ between two extreme, unacceptable answers: empirical idealism, which takes the requirements of a rule in any given situation to be constituted by our reaction to the case; and hard platonism, which takes these requirements to be delivered by unvarnished reality as absolutely the simplest or most natural way to (...) carry on. Tellingly, however, McDowell's position is itself unacceptably idealist in his picture of the way in which we are ‘involved’ on the right-hand side of biconditionals such as, ‘“Diamonds are hard” is true if and only if diamonds are hard’.In response to this stultifying state of affairs, I suggest that McDowell has followed the empirical idealist and hard platonist in assuming that the requirements of a rule must be grounded by something else: something external to the rule, which mediates between the rule and the standard for its correct application. This assumption is false. What is more, one application of a metaphor to which Wittgenstein has a somewhat equivocal relation—that of rules as rails invisibly laid to infinity—can help this point to stick. (shrink)