Because we have parts of our brain that supervise other parts of our brain and evaluate its output. For example: if you smoke pot and get paranoid, it's becaus

Because we have parts of our brain that supervise other parts of our brain and evaluate its output. For example: if you smoke pot and get paranoid, it's because pot dials back the work of the part of your brain that prunes thought paths that are not applicable. Normally, paranoid thoughts do not make sense, so they are discarded. That's also why you're more 'creative' when you smoke pot, less thought paths are pruned and more stuff that doesn't quite make sense gets through. Or thoughts that overly focus on some details get through, which are normally not required. Our brains are inherently "higher level", current AI is hopelessly simplistic by comparison.