Full Idea
You can think 'brown dog' without thinking 'cat', but you can't think 'brown dog' without thinking 'brown' and 'dog'.
Gist of Idea
You can't think 'brown dog' without thinking 'brown' and 'dog'
Source
Jerry A. Fodor (LOT 2 [2008], Ch.4.3)
Book Reference
Fodor,Jerry A.: 'LOT 2: the Language of Thought Revisited' [OUP 2008], p.112
A Reaction
Fodor is talking about concepts in thought, not about words. The claim is that such concepts have to be compositional, and it is hard to disagree.