The belief that economics can be a science has led many an economist to search for the economic equivalent of E=Mc2 or the elusive Grand Unified Theory; a search for huge if not quite all-embracing truths that can be expressed as mathematical algorithms or, more simply, as slogans. Examples include Karl Marx’s “the workers must own the means of production” or the neoliberals’ “leave it to the market”. These slogans-qua-algorithms are then treated as ideologies, and the ideologies in turn are treated as principles, which become causes, and are then treated as ends in themselves. Thus people have died in their tens of thousands for the cause of “Marxism”, and the world as a whole is currently crippled by the crude ideology of neoliberalism. Yet in truth the only principles worth fighting for – the only ideas that should be called “principles” at all — are the bedrock principles of morality and ecology. Slogans and ideologies are useful insofar as they may express those principles, and so the ideas of Marx deserve to be taken seriously because Marx was a serious moralist and his ideas are rooted in the moral principle of justice, which is closely related to the bedrock moral principle of compassion. But Marx himself denied being a “Marxist”.