Here's an article that summarises Searle's Chinese Room and the major responses to that thought experiment. The central problem with these arguments is the lack of criteria. Because we don't really understand the nature of consciousness, it's hard to say where imitation of conscious behaviour stops and genuine consciousness begins. Searle paints one end of the debate quite nicely: symbol processing without understanding is not consciousness, no matter what behaviour it produces (a point not everyone agrees with). But how far do we have to move from that point before we do have consciousness.