Practical reasoning for serial hyperspecializers

Some species are weedy: they move from one ecological niche to another. Other species are specialized: they are exquisitely adapted to exploit a particular niche. Human beings are the design solution in which a species is simultaneously weedy and specialized - the trick being to manage the exquisite niche-specific adaptations in software rather than in the hardware. We are built to reprogram ourselves on the fly, to select new goals, new priorities and new guidelines appropriate to novel niches. Understanding ourselves as an implementation of this design solution has consequences for the theory of practical reasoning. Instrumentalism (the theory of practical reasoning according to which it consists solely in selecting means to pre-given ends) cannot be a suitable theory of rationality for such a species (that is, our own).