Are we teleologically essentialist?

People may conceptualize certain categories as held together by a category-specific ‘essence’—some un- observable, critical feature that causes the external features of a category to emerge. Yet there remains an open question about what comprises this essence. Recently, Rose and Nichols have argued that this essence is comprised of tele, or purposes, (and, in turn, that teleology is the internal force that gives rise to external features). However, Neufeld has challenged this work on theoretical grounds, arguing that these effects arise only because people infer an underlying internal change when reasoning about a change in telos. On Neufeld’s view, it is the underlying internal cause, and not the telos itself, that serves as an essence (consistent with classic views of scientific essentialism). Here, we ask: Is teleology the primary force behind psychological essentialism? We begin by successfully replicating Rose and Nichols’ key findings in support of teleological essentialism. In two further experiments, however, we demonstrate that teleology may not the central way that people understand the essences of living things: Internal changes matter at least as much as changes to teleology. These findings suggest that while teleology may be one important cue to category membership and the essences of living things, it may be premature to say that we are ‘teleologically essentialist.’