Locke and Leibniz deny that there are any such beings as ‘monsters’ (anomalies, natural curiosities, wonders, and marvels), for two very different reasons. For Locke, monsters are not ‘natural kinds’: the word ‘monster’ does not individuate any specific class of beings ‘out there’ in the natural world. Monsters depend on our subjective viewpoint. For Leibniz, there are no monsters because we are all parts of the Great Chain of Being. Everything that happens, happens for a reason, including a monstrous birth. (...) But what about materialism? Well, beginning with the anatomical interest into ‘monstrous births’ in the French Académie des Sciences in the first three decades of the eighteenth century, there is a shift away from ‘imaginationist’ claims such as those of Malebranche, that if a woman gives birth to a monstrous child it is a consequence of something she imagined. Anatomists such as Lemery and Winslow try to formulate a strictly mechanical explanation for such events, rejecting moral and metaphysical explanations. Picking up on this work, materialist thinkers like Diderot are compelled to reject the very idea of monsters. We are all material beings produced according to the same mechanisms or laws, some of us are more ‘successful’ products than others, i.e. some live longer than others. In his late Eléments de physiologie he says “L’homme est un effet commun, le monstre un effet rare.” Ultimately he arrives at a materialist version of Leibniz’s position: there are no monsters, we are all monsters in each other’s eyes, at one time or another. This conclusion is a pregnant one in light of twentieth century interest in the problem of ‘the normal and the pathological’ (Canguilhem), and the broader question of how materialism relates to the biological world. (shrink)