The "normative" defines a traditional faultline between philosophy and the social sciences. On the one side lies what we ought to do, on the other what we actually do. The difference between the two is quite controversial and not a little mysterious. What grounds the capacity to make, break and maintain the norms that define our collective condition as human? If some supreme sovereign power is required, does this dictator dwell outside or inside of us - and how does its chain of command operate?
Recently it has become common to interpret these questions as a cross-disciplinary face-off between sociology and biology. Whenever sociologists say that norms are internalised through institutionalised forms of learning, biologists insist that in reality these are adaptations that externalise genetic tendencies in specific environments.
Stephen Turner's subtle examination avoids both faces of this crude mirror but shares a concern that arises from looking at them at the same time: what else is there to a norm in the strong obligatory sense that is not already captured in the empirical sense of norm, namely, what regularly happens in society?
This question is important for historical and contemporary reasons, both of which are skilfully blended in this text.
On the one hand, in the early 20th century, psychology, sociology and political science managed to establish expertise over areas previously covered by theology, philosophy and law by eroding, if not eliminating, the difference between the two senses of norm.
On the other hand, in the early 21st century, there remains an active trade in analytic philosophy of mind and language trying to claw back some of the lost ground at a time when increasingly diffuse patterns of human behaviour threaten to divest "norm" of any clear meaning.
Turner astutely observes that the strong obligatory sense of norm is an artefact of late Roman law that has no clear precedent in other legal traditions. The relevant innovation is the idea of freely binding one's actions in certain accountable ways.
By contrast, in societies untouched by Rome, people's behavioural expectations have been largely determined by their roles, which are prescribed by such naturalistic means as birthright. Nevertheless, throughout the modern period, especially after Kant, a universal sense of obligation has been claimed for the rational person's adherence to law, ethics and logic.
From Turner's perspective, the history of social science has been one long struggle to get philosophers to admit the empirical eccentricity of the Kantian position - that such latter-day Kantians as John Rawls and Jorgen Habermas are much more parochial than advertised. Turner characterises this struggle as the de-supernaturalisation of the normative, by which he means to recall the Christian roots of the obligatory sense of norm in the "self-legislating" individual who can tell the difference between what is normally done and what she ought to do by virtue of personal commitment.
Thus, philosophers have been on a mission to find God in the secular garb of normativity. The book begins with the great lawyer Hans Kelsen's multiple strategies to prevent the idea of legality from blending into Max Weber's sociology of law. Similar examinations are then made of the Pittsburgh philosophers Wilfrid Sellars, John McDowell and Robert Brandom, who try to provide social accounts of inference and justification that do not simply reinvent Durkheim with a lot more complexity and a lot less data.
In the end, Turner believes that all these philosophical projects are doomed to failure because they are seeking something that does not exist.
Turner's very clear and measured writing can easily underplay the significance of his message, which needs to be taken very seriously by anyone concerned about the future of philosophy and the social sciences.
Explaining the Normative
By Stephen P. Turner. Polity Press. 240pp, £55.00 and £18.99. ISBN 9780745642550 and 42567. Published 26 March 2010