the thinking carried on in those sciences. Logic, as we have said, studies the way in which we already think about things. Nevertheless, it is not without effect upon our ordinary thinking. A good deal of our so-called thinking is incoherent, and breaks down when we criticize it. That we can indeed discover for ourselves without learning Logic; an economist can correct his own or his predecessors’ errors in political economy, a mathematician in mathematics; they could no more wait for the logician