Rationality is even trickier. Is rationality simply internal consistency of choice? Obviously not, Sen replies. A person may very well be consistently moronic. Moreover, he argues, internal consistency is not even a necessary condition for rationality: when the reasoning involved in making choices is very complex, it is hard to even see what internal consistency would mean. Is rationality simply self-interest maximisation? No, for we can act on a variety of motives. It is question-begging to assume that self-interest is the only motive that is rational for us to have. Is rationality just pure and simple maximisation? Again, Sen argues, it is foolish to think of maximisation independently of a discussion of what it is that we wish to maximise. Any attempt to derive a purely formal definition of rationality is doomed to failure. As with freedom, rationality, the discipline of subjecting one’s choices to reasoned scrutiny, turns out to be a multi-faceted concept.
Rationality and freedom get even more complicated when you throw in the problem of social choice. How can the preferences each one of us has about how society should be run be reconciled with the preferences of others? Can we simply aggregate individual preferences to produce a social welfare function? Modern social choice theory, of which Sen is an undisputed master, labours under the shadow of Arrow’s famous theorem that argued that no social welfare function could simultaneously satisfy certain minimal conditions, each of which we might have an independent reason to value. One of its implications was taken to be that any aggregated social welfare function may be a violation of someone’s freedom. To this, Sen adds that there might even be a tension between unlimited freedom of contract and the existence of a protected sphere of rights. How do you then reconcile freedom and social choice?
This volume has an astonishing range of arguments about freedom, rationality and social choice. Sen’s critique of the narrowness of economics is characteristically thorough. But equally striking is his vast imaginative sympathy. While he never lets life’s complexity be sacrificed to theoretical abstraction, he doesn’t either make that complexity an excuse for not thinking rigorously.
This is very much an academic volume. The discussions are often dauntingly technical. But even for the technically-challenged, this volume might be a rewarding one. Rationality and Freedom is a striking tribute to its author, eminently reasonable in its conclusions and driven by a passion for human freedom in its widest sense. The intellectual range and subtlety on display explains not only why Sen is the philosophers’ favourite economist and the economists’ favourite philosopher, but almost everyone’s favourite intellectual.
