Martin Hollis and Edward J. Nell's 1975 book offers both a philosophical critique of neo-classical economics and an innovation in the field of economic methodology. Further, they outlined an alternative vision to neo-classicism based on a rationalist theory of knowledge. Within neo-classicism, the authors addressed consumer behaviour (in the form of indifference curves and simple versions of revealed preference theory) and marginalist producer behaviour in both product and factor markets. Both are based on rational optimizing behaviour. They consider imperfect as well as perfect markets since neo-classical thinking embraces many market varieties and disposes of a whole system for their classification. However, the authors believe that the issues arising from basic maximizing models have extensive implications for econometric methodology (Hollis and Nell, 1975, p. 2). In particular it is this class of models – rational behavior as maximizing behaviour – which provide support for specification and identification. And this, they argue, is where the flaw is to be found. Hollis and Nell (1975) argued that positivism (broadly conceived) has provided neo-classicism with important support, which they then show to be unfounded. They base their critique of neo-classicism not only on their critique of positivism but also on the alternative they propose, rationalism. Indeed, they argue that rationality is central to neo-classical economics – as rational choice – and that this conception of rationality is misused. Demands are made of it that it cannot fulfill.