In his recent review of the 'Ecological perception debate' in this journal, Ginsburg (1990) concluded:The debate dealt with issues and assumptions that go to the heart ofcontemporary psychology and social psyrhology. On the other hand, the debate has not had serious impact on mainstream psychology or social psychology, reflecting in part the fringe status of the journal with respect to those disciplines. But participants in the debate are publishing in their disciplinary media, and to the extent the participants have had their thoughts sharpened by the debate, the disciplines will benefit. (p. 362).A cheerful conclusion, but potentially limiting, as though thejournal were like a yoga class or a game of squash that set one up for the real business of life. That way disciplines may be invigorated and fortified, but are unlikely to be disturbed in their isolation. Ecological Psychologists have always been suspicious of the boundaries that legitimise such conceptual and institutional isolations -between organism and environment, or sensation and perception, and we may add, if we are mutualists, between theoretical discussion and laboratory practice, or between social and mainstream psychology.Mutualism is not new, but has recently become a label and a theme in conference papers (Still, 1987;Good and Still, 1988; Good, 1990, 1991) and in print (Still and Costall, 1989; Leudar, 1991). There is no exact definition ofmutualism. Mutualist concepts, including that ofmutualism itself, are flexible and change over time. Nevertheless, and bearing this in mind, atlempts at a definition may prove a useful starting point. The word 'mutualism' has been in occasional use for over 100 years in politics and in biology. In politics, according to the third edition ofthe Shorter OxfordEnglish Dictionary, it is "the doctrine that individual and collective well-being is attainable only by mutual dependence", while in biology it is "A condition ofsymbiosis in which I 06 two associated organisms contribute mutually to the well being of each other". More recently the word has been used in psychology to refer to an approach stemming from the Ecological Psychology of J. J. Gibson, and centred on the view that organism and environment cannot be treated independently (Leudar, 1991). 'Environment' for human beings includes other people and even the so-called physical environment is dominated by social factors -it is only through sharing the world of others during development in infancy and formal education that we gain knowledge of the environment, physical as well as social. Such a mutualism has more far-reaching implications in psychology than in politics or biology, especially at present, when psychology is still dominated by a cognitivism whose starting point is the study of the mind in isolation from its environment (Fodor, 1980;Still, 1986). There are signs that these implications are being spelt out for psychology in a variety ofcontexts; in dialectical psychology (Buss, I 979; Riegel, 1979); contextualism (Morris, 1991 ; Rosnow and Geo...