Instrumental Rationality and Carroll's Tortoise

Some philosophers have tried to establish a connection between the normativity of instrumental rationality and the paradox presented by Lewis Carroll in his 1895 paper “What the Tortoise Said to Achilles.” I here examine and argue against accounts of this connection presented by Peter Railton and James Dreier before presenting my own account and discussing its implications for instrumentalism (the view that all there is to practical rationality is instrumental rationality). In my view, the potential for a Carroll-style regress just shows us that since instrumental rationality involves a higher-order commitment to combine our willing an end with our taking the necessary means, it therefore cannot, on pain of regress, itself be added as a conjunct to one of the elements to be combined. This view does not support instrumentalism.