What is the scope of human thought? Is there a limit on what we can grasp in thought? ‘The limits of thought’ focuses on whether there are thoughts that we cannot entrain and whether there are aspects of reality from which we are cognitively closed. It might seem that this idea does not make sense since the contrast between thought and perception is that thought is not limited in the same way that perception is. Counter to this is that if we accept that there is a limit the level of a chimpanzee's thoughts (e.g. quantum mechanics) then there must be regions of reality that we are unable to grasp. How do we determine these regions?