Hempel’s analytic behaviourism is the view that mental states are a private phenomenon, so cannot be verified in a public, intersubjective sense. Thus, we have to talk about them in terms that are empirically verifiable i.e. behavioural states. Since Hempel believes that talk of mental states are completely reducible to behavioural states, when we talk about agential behaviours i.e. actions that agents perform with intention, we should be able to translate them into colourless descriptions i.e. movements performed by non-agents. In other words, statements describing mental states can be translated, without loss of meaning, into statements describing possible and actual behaviour. Thus, analysis of mental states must only contain non-mentalistic vocabulary e.g. the mental state of a toothache can be wholly explained by bodily behaviours such as crying or brain processes such as increased activity in the amygdala.The challenge facing hard behaviourism is to produce an analysis of mental terms using non-mentalistic vocabulary that employs behavioural descriptions alone. The general circularity problem claims that the analysans i.e. the translation of mental states into behaviours, contains the analysandum i.e. mental states. For example, if Hempel were to translate the mental state of being sad, he would talk about linguistic behaviour like telling someone that they are upset. However, the use of language implies the intention to communicate and an understanding of language i.e. mental states. Mental states cannot be analysed without reference to other mental states. This leads on to the problem of specific circularity, which states that definition of mental state A will require reference to other mental states as part of its analysis which, when themselves defined, will ultimately require reference to A. For example, a person who is sad will display the behaviour of weeping. However, they will only weep because they think that doing so will attract attention. However, the only want to attract attention because they are sad. Thus, the analysis of the mental state leads us back to the mental state itself. Thus, the core principles that underlie behaviourism are contradictory and the theory has no solid ground to stand on.