It seems to me that there are two vital mistakes in Marxist theory, and that these two mistakes go a long way towards accounting for the failure of Marxism in practice. The first error is that it attempts to offer a 'philosophy of history', in the sense of an account of how history works; the second, that it has on the whole embraced, implicitly or explicitly, the Utilitarian position in ethics, and embraced it in a crude and untenable form. Since the latter is common also among many Liberals, it is the former error which must account for most of the difference in practice between Communist and Liberal. The fundamental weakness of the Communist must be his belief that he has uncovered the springs and cogs of history, and is therefore able to predict its future course, if not with complete precision, at least with certainty.
(I. M. Crombie, "Social Clockwork and Utilitarian Morality," in Christian Faith and Communist Faith: A Series of Studies by Members of the Anglican Communion, ed. D. M. MacKinnon [London: Macmillan & Company, 1953], 98-113, at 100-1)
Keith Burgess-Jackson, J.D., Ph.D. 