Perhaps the best way of understanding the behaviourist approach is to compare it with that of Descartes. Descartes wants to argue that an individual’s mind is private and that the meaning of the thoughts contained therein in private (unless of course we want to share them publicly via speech). This approach assumes that individual’s have what is termed “privileged access” to the contents of their minds – in other words, no one else can know your mind as well as you do.

A logical behaviourist would probably not disagree with the fact that you are the best person to know what you are thinking, but they would certainly not agree that this makes mental events totally private. From the behaviourist view, the meaning of even the most private emotion is potentially observable – and therefore public. The main criticism of Descartes here is the idea that thoughts can exist as mental events separate from the body. For instance, if I say, “Dave is troubled”, it is a perfectly logical possibility – according to Descartes’ theory – for there to be no observable evidence of this at all, since mental events are private. However, the behaviourist wants to argue that to say, “Dave is troubled” is to say something about his behaviour: perhaps he is frowning or looking sad.

A critic of this view might point out that it is not always possible to judge people’s emotions by their body language – in other words, that some things must necessarily stay private. However, the behaviourist would reply that surely we must judge Dave’s moods by some possible observable behaviour. Even if Dave hides his worries and only lets his mask drop in private behind closed doors, that is at least a potentially observable event. Furthermore, if there could never be such a possibly observable behaviour, then the behaviourist would consider the statement as meaningless.

In this way logical behaviourism is picking up where logical positivism left off. For logical positivism, the meaning of a statement is established by its method of verification. So, if there is no possible method of verification, then the statement is not a factual one and possibly meaningless. In a similar way, mental statements that cannot be translated into a statement about some actual or possible form of behaviour are considered to be meaningless.