Mss (ts) entitled 'Experimental psychology, behaviourism and solipsism' (part I of 'The theory and practice of knowledge') There is an annotation on it (by ?Evelyn Lawrence, Nathan Isaacs' second wife) noting that Nathan Isaacs' published work 'The foundations of common sense: a psychological preface to the problems of knowledge' (Routledge and Paul, 1949) is a shortened version of it and that this version is not to be published. c.1949