Full Idea
Anti-individualism is the view that not all of an individual's mental states and events can be type-individuated independently of the nature of the entities in the individual's physical or social environment environment.
Gist of Idea
Anti-individualism says the environment is involved in the individuation of some mental states
Source
Tyler Burge (Philosophy of Mind: 1950-2000 [2005], p.453)
Book Reference
Burge,Tyler: 'Foundations of the Mind' [OUP 2007], p.453
A Reaction
While the Twin Earth experiment emphasises the physical environment, Burge has been responsible for emphasising the social environment. The suspicion is that the whole concept of 'individual' minds will collapse on this view.