Blockhead is the name of a theoretical computer system invented as part of a thought experiment by philosopher Ned Block, which appeared in a paper entitled Psychologism and Behaviourism. In this paper, Block argues that the internal mechanism of a system is important in determining whether that system is intelligent, and also claims to show that a non-intelligent system could pass the Turing Test. Block asks us to imagine a conversation lasting any given amount of time. He states that, given the nature of language, there are a finite number of syntactically and grammatically correct sentences that can be used to start a conversation. From this follows the point that there is a limit to how many correct responses can be made to this first sentence, and then again to the second sentence, and so on until the conversation ends. Block then asks us to imagine a computer which had been programmed with all these sentences. Although t