I demonstrate that locking on, a key notion in Jerry Fodor's most recent th
eory of content, supplemented informational atomism (SIA), is cashed out in
terms of asymmetric dependence, the central notion in his earlier theory o
f content. I use this result to argue that SIA is incompatible with the lan
guage of thought hypothesis because the constraints on the causal relations
into which symbols can enter imposed by the theory of content preclude the
causal relations needed between symbols for them to serve as the elements
of the medium of thought.