Cognitive Science is the endeavour to model
thought processes and
cognitive representations (and the subsequent
intelligent behaviour that arise from them) in purely scientific terms. Currently, the main focus of Cog. Sci. is to resolve the
behavioural and
cognitive levels of mental activity - the
biological aspect is not given as much attention, because we currently lack the tools to investigate it thoroughly. Cog. Sci. has very strong links with
Linguistics and
Artificial Intelligence (
Chomsky has a lot to say about the subject). It's currently quite a young discipline, with the potential to branch off in several directions and to alter its objectives and stance on several key issues as advances in its related fields filter through.
If the human brain was simple enough for us to understand, we'd be too simple to understand it.