The two main varieties of AI are called "strong" and "weak". Strong AI argues that it is possible that one day a computer will be invented which can be called a mind in the fullest sense of the word. In other words, it can think, reason, imagine, etc., and do all the things that we currently associate with the human brain. Weak AI, on the other hand, argues that computers can only appear to think and are not actually conscious in the same way as human brains are.