Indeed Marx himself had not the time or means to adopt an attitude, so to speak, towards the _purists_, or the _hedonists_, or the _utilitarians_, or the _deductive_ or _Austrian_ school, or whatever else they may call themselves. But he had the greatest contempt for the _oeconomia vulgaris_, under which term he was wont to include also the researches of general economics, which explain what needs no explanation and is intuitively evident, and leave unexplained what is more difficult and of genuine interest. Nor has Engels discussed the subject; but an indication of his opinion may be found in his attack on Dühring. Dühring was struggling to find a general law of value, which should govern all possible types of economic organisation; and Engels refuted him: 'Anyone who wishes to bring under the same law the political economy of Terra del Fuoco and that of modern England, can produce nothing but the vulgarest commonplaces.' He scorns the truth of ultimate instance, the eternal laws of value, the tautologous and empty axioms which Herr Dühring would have produced by his method.[32] Fixed and eternal laws are non-existent: there is then no possibility of constructing a general science of economics, valid for all times and in all places. If Engels had meant to refer to those who affirm the eternity and inevitability of the laws characteristic of capitalist society, he would have been justified; and would have been aiming his blows at a prejudice which history alone suffices to refute, by showing as it does, how capitalism has appeared at different times, replacing other types of economic organisation, and has also disappeared, replaced by other types. But in Dühring's case the criticism was much beside the mark; since Dühring did not indeed mean to set up the laws of capitalist society as fixed and eternal; but to determine _a general concept of value_, which is quite another matter: or, in other words, to show how, _from a purely economic point of view_, capitalist society is explained by the same general concepts as explain the other types of organisation. No effort, not even that of Engels, will suffice to stop such a problem from being stated and solved; unless it were possible to destroy the human intellect, which, in addition to particular facts, recognises universal concepts.