In his fourth Reith Lecture from his series 'Minds, Brains and Science', John Searle, Professor of Philosophy at the University of California, Berkeley, analyses the structure of human actions.

In this lecture entitled 'Walk to Patagonia', Professor Searle draws together the mental and physical aspects to show how our mental activities can produce our behaviour. Can our ability to choose our movements be what separates us from machines? Professor Searle seeks to show how the structure of an action relates to the explanation of it.