              So far, then, Aristotle’s four causal schema has whatever intuitive plausibility his illustrations may afford it. He does not rest content there, however. Instead, he thinks he can argue forcefully for the four causes as real explanatory factors, that is, as features which must be cited not merely because they make for satisfying explanations, but because they are genuinely operative causal factors, the omission of which renders any putative explanation objectively incomplete and so inadequate. 