Works at what? Making us more chaste, more pious? More devoted to the coming revolution? to the thousand year Reich? Don't you have to have criteria for selecting what is worthwhile, criteria that precede whatever it is that's supposed to "work"?
Flipping around in Scruton's Modern Philosophy, an Introduction and Survey I find myself vindicated:
Simple definitions of truth in terms of utility seem transparently absurd...Obviously, if we say that a belief is true when useful, we must know what we mean by 'useful'. Anyone seeking a career in an American university will find feminist beliefs useful, just as Marxist beliefs were useful to the university apparatchik in the Soviet Union (not to speak of Britain or Italy). But this hardly shows those beliefs to be true. So what do we mean by 'useful'? One suggestion is: part of a successful scientific theory. But what makes a theory successful? (Marxism was successful, if you mean that it was spread to a large number of beliebers.) Some say that a successful theory leads to true predictions. But if we take that line, we end by defining utility in terms of truth. Indeed, it is hard to find a plausible pragmatism that does not come to this conclusion: that a true proposition is one that is useful in the way that true propositions are useful. Impeccable, but vacuous. (pp.104-5)