I cannot give you a detailed solution to the problem of distinguishing between "rational" and "reasonable", not only because I do not have the time, but also because I am by no means sure what to say. But I do think that I know two keys to the solution of this problem. The first key is that "reasonable", unlike

"rational", is really a privative term; "unreasonable" is, as some were once wont to say, the "trouser-word" in this particular pair of complementaries. To be reasonable is to be (relatively) free from unreasonableness; and to be very reasonable is to be free from a high degree of unreasonableness which one might (or some might) have been expected to exemplity or display in the circum-stances. The second key is provided by Aristotle; in Nicomachean Ethnics I, he remarks that both the ratiocinative and the non-ratiocinative (or desiderative) parts of the soul may have reason; the former intrinsically, as the source of rational principles or precepts, the latter extrinsically, as heeding or listening to those principles or precepts. My idea is to link the first of Aristotle's interpretations of "having reason" with the word 'rational, and the

second with the word reasonable. In application to behaviour, to be rational is to possess (or, on a given occasion, to display) the capacity to reach principles or precepts relating to conduct; to be reasonable is (in general or on a particular occasion) to be freefrom interference, on the part of desire or impulse, in one's following such principles or precepts.