Abstract

Too much rationalist social philosophy is polarized into radical and conservative factions, both seeking support for rival claims to intellectual authority. Moreover, each faction can raise what it sees as a valid critique of the other. To the uncommitted, this mutual critique presents a reductio ad absurdum of rationalism and invites violence and despair. The radicalist claim that a rationalist social philosophy is necessarily radical clashes with the conservative critique which sees radicalism demanding the impossible from reason. So the question is whether this radical controversy between opposing rationalisms is amenable to rational resolution.This question is addressed through an examinalion of three writers: two radicals, Jean-Paul Sartre, who presents a comprehensive rationalism, and Herbert Marcuse, whose rationalism is irrationally grounded and authoritarian, and a conservative, Karl Popper, whose critique of comprehensive rationalism is effective against Sartre’s view, but whose own concession to irrationaIism unwittingly supports Marcuse’s approach.Yet, if Popper’s approach can be improved by abandoning both polarization and the exclusion of all radicalism, then we may have a rational social philosophy of a new non-authoritarian sort. The prospects for such a new approach are considered in the last section.