Verbal Propositions and Apparent Inference
Mill’s attitude to traditional Aristotelian theory on these matters is two-sided-a case of his favourite Coleridgean policy of finding in old traditions valuable truths clothed in misleading forms. He wants to free the schoolmen’s Aristotelian doctrines of classification and definition from their essentialist underpinnings. But he accepts that an important truth is contained in their notion of ‘natural kinds’. ‘Kinds have a real existence in nature’ (i.vii.4)—the problem is to explain what constitutes a natural kind without relying on essences. Mill rightly sees that the notion of natural kinds plays an indispensable role in scientific-or indeed any-thinking about the world; he accepts that that fact calls for explanation from an essence-dispelling radical empiricist. His positive theory, which is that a natural kind of object, or a natural kind of stuff, is set apart by ‘an indeterminate multitude of properties not derivable from one another’ (VII 126) hardly rises to the real issues, though it does raise interesting questions of its own. We shall not pursue it,1 but we shall examine the negative side of the case, namely, his rejection of essential properties.