Aristotle is arguably the first philosopher who explicitly claimed that things can be divided into natural kinds, i.e. groups that are genuinely unified by some objective common property and play an explanatory role in science. This view has been extremely influential not only in philosophy but also in biology, a discipline that was first developed by Aristotle. In particular, it inspired the early modern project of classifying animals into genera and species. Aristotle’s classification of animals, however, has some surprising features that make it alien to readers accustomed with later classifications, such as Linnean taxonomy, and have even prompted some scholars to claim that he did not have a classification of animals. I will first highlight how Aristotle’s philosophy (and reactions against it) has shaped our way of thinking about biological kinds until the present day. I will then concentrate on Aristotle’s claim that some species are ambiguous between two kinds, and belong to “neither and to both”. I will argue that this surprising assertion is compatible with Aristotle’s essentialism, but that it nonetheless upsets some standard assumptions on what Aristotelian essentialism is.
Nicola Carraro obtained a PhD from the University of Munich in Germany, and held teaching and research positions in Germany, the US, France, and Brazil. He has published on Aristotle’s conception of the soul and on his reception of Presocratic thinkers. His main research interests are Aristotle’s metaphysics, his conception of nature, and his philosophy of biology. He is currently a Junior Thyssen Fellow at IAS CEU with a research project on Aristotle’s conception of biological kinds.