Internalism in philosophy of mind is the thesis that all conditions that constitute a person's current thoughts and sensations, with their characteristic contents, are internal to that person's skin and contemporaneous. Externalism is the denial of internalism, and is now broadly popular. Joseph Mendola argues that internalism is true, and that there are no good arguments that support externalism. Part I examines famous case-based arguments for externalism due to
Kripke, Putnam, and Burge, and develops a unified internalist response incorporating rigidified description clusters. Part II examines theoretical motivations for externalism entwined with causal
accounts of perceptual content, and develops an internalist but physicalist account of sensory content involving intentional qualia. Part III examines theoretical motivations for externalism entwined with externalist accounts of language, including work of Brandom, Davidson, and Wittgenstein, and develops an internalist account of thoughts mediated by language.