  The causally problematic feature for externalism is this contextual or relational component of representational mental states. Suppose that our mental representations are physical structures in the brain. Now suppose with the externalist that the content of these representations is determined, not just by our intrinsic features, but by context as well. Lilian (or Lilian’s brain) represents a tree in the quad by going into state T. But T represents a tree in the quad, not by virtue of T’s (or, for that matter, Lilian’s) intrinsic makeup, but by virtue of T’s (and by extension Lilian’s) standing in the right kind  of relation to the tree. The very same kind of state in a different  context (in the brain of someone in different circumstances) might  represent something very different—or nothing at all.