Full Idea
Davidson argues that knowledge of other minds presupposes knowledge of one's own mind, and that there is no knowledge of other minds without knowledge of the external world.
Gist of Idea
Knowing other minds rests on knowing both one's own mind and the external world
Source
report of Donald Davidson (Three Varieties of Knowledge [1991]) by Michael Dummett - Common Sense and Physics Ch.10
Book Reference
Kusch,Martin: 'Knowledge by Agreement' [OUP 2004], p.124
A Reaction
Davidson't argument is actually hard to swallow because it is so long and complex. Compressing the point makes it begin to sound like a variant of the argument from analogy.