Rational and Irrational

Hume asserted that 'reason is and should be the slave of the passions'. What he meant is that Reason has no motive power in itself, and is involved in conduct only as a calculator of the best means to ends that are set by the Passions. Kant responded by arguing that Reason does master the Passions, not when performing such calculations, but when overriding any specific personal passion with the objective consideration of what any person would do. This exchange is perhaps the most historically prominent phase of the debate over whether humans are fundamentally Rational, or fundamentally Irrational. One point of agreement between Hume and Kant is that a Cause precedes an Effect, which means that they agree that any motive would have to precede action. But, prior to Kant, Reason was always taken to be 'Theoretical', i. e. subsequent to its object. So, in order to defend Rationality, Kant conceives of a volitional 'Practical Reason' that would precede action, and, hence, could therefore, at least in principle, have motive power. In particular, its mastery over Passion, according to his analysis, is based on a respect for the Rational principle. But that leaves him open to the challenge that such respect is the actual motivational force in play, and that respect is another Passion, thereby validating the Irrationalist argument. However, the whole debate, or at least at this phase, turns on the assumption that a cause must precede an effect. That assumption, in turn, presumes that the only cause is Efficient Causality. Instead, Formal Causality can either be simultaneous with or subsequent to its corresponding Matter. So, if Reason and the Passions are construed as having a Form-Matter relation, then neither need be established as prior to the other, and conduct need not be categorized as exclusively Rational or exclusively Irrational.