Matthew Kern

The psychological immune system is said to be a suite of cognitive traits and defense mechanisms designed to protect the self from affectively threatening information, at the expense of tracking the truth. The PIS construct has been advanced by authors such as Norman et al. (2024) and Sedikides (2021) as referring to a real psychological system. I argue for ontological skepticism about the PIS but defend the usefulness of the concept as an idealization (Potochnik 2017) that illuminates psychological causal patterns. Lastly, I argue that work on the PIS can productively refine Tekin (2025)’s MuSe model of the self.

According to Jerome Wakefield’s harmful dysfunction account, a mental disorder must involve an objective dysfunction couched in evolutionary terms. However, selected effects functions are indeterminate because (i) the same trait can be both selectively advantageous and disadvantageous, and (ii) the functional activity of a trait can be assessed according to conflicting norms, given the trait’s place in a hierarchy of functions. Therefore, there may be a dysfunction that can be described in multiple empirically adequate ways. The choices involved in these cases are value-laden. Some cases of addiction may fit this mold, involving indeterminacy that invites opposing value judgments.