A delicate task faces the historian of thought whenever an established doctrine, what in the language of current fashion is called a paradigm or, more recently, a 'research programme', is challenged. He has to trace the genealogy of the challengers. To this end he must pick up threads covered by the sands of time, dust them, and try to connect them with the new skein of thought.
His task is all the more difficult, but also the more urgent and rewarding, since history of thought is almost invariably written from the point of view of the reigning orthodoxy. For Schumpeter, Walras's system is the crowning achievement, hence every earlier economist is either a predecessor or belongs to a lost tribe. From such a perspective most unorthodox strands of thought appear as blind alleys if they are mentioned at all. By the same token the challengers must seem 'rootless' iconoclasts. Nevertheless, the historian cannot rest or claim to have completed his task until he has unearthed at least some of the historical roots of the ideas of the challengers of his day.
Professor Shackle's Epistemics and Economics (1972) is a case in point. His bold challenge to neoclassical orthodoxy, with its determinism borrowed from the natural sciences and with its bland assumption of a world sufficiently tranquil and restful to provide us with a set of supposedly constant 'data', is bound to have far-reaching repercussions. Although neoclassical orthodoxy is the main target of his attack, the subtitle of his book A Critique of Economic Doctrines (we may note the plural) indicates a wider scope. Some economic doctrines of our time, we may surmise, invite more trenchant criticism than do others.