Jean-Pierre Changeux is arguably one of the great neuroscientists of our day and certainly France’s most famous. His writing is lucid and engaging, and in the tradition of other French authors he writes books which appeal to a wide audience. In The Physiology of Truth Changeux takes us on a whirlwind tour of the progress of neurosciences to outline his personal view of how human being should relate to both their physical surroundings and each other. What results is a kind of hopeful naturalism, an attempt to explain an evolutionary basis for a neurobiology of truth.

The core of Changeux’s thesis lies in the philosophically ancient and yet still relevant question: how can we know the world as it really is? Changeux’s response is multidisciplinary, and as such he draws on neuroscience, philosophy, social psychology, linguistics, molecular biology and computer modelling. He aims to show that the evolution of the human brain can provide an explanatory basis not only for the behaviour of humans, but also that the way the brain is structured to provide representations of the world that are both reliable and profound. In short, objective knowledge does exist, and our brains have evolved the equipment to recognise it. To the old question, ‘what is truth?’, Changeux answers ‘cerebral representations’, which are themselves physical objects (pp. 37, 60). The brain is a ‘truth apparatus’ (p. 152).

Changeux’s hypothesis offers a challenge to two fundamental and popular models of the brain — namely, the general functionalist idea that the brain is modular and no more than a sophisticated computer and the nativist view that the brain is a genetically inherited and determined organ. If Changeux is correct, and the brain is not only able to produce objective knowledge, but is in some sense evolved in order to do so, it is possible to see how neither the functionalist nor nativist views hold. Rather, Changeux would argue, language, truth and morality are products of our genes and molecular composition. (Changeux has elaborated this in more technical papers and in collaboration with Stanislas Dehaene and Michel Kerszberg as the idea of ‘neuronal workspace’, a ‘dense network of corticocortical connections’ [p. 95]; here, he even finds support in Diderot for the network view of the brain as ‘neuronal architecture’ and suggests that philosophically this should lead us to argue for a more sophisticated materialism.) The brain is neither a passive receptacle of external input (a mistake Changeux calls ’empiricism’) nor an innately wired genetic machine but a locus of autonomous activity (here he refers to the work of Alain Berthoz); this builds on decades of work on the ‘epigenetic’, self-organized model of the brain.

Drawing on recent and challenging findings in the neuroscience of both humans and primates, and the psychophysics of perception and judgement, Changeux makes the case that belief in objective knowledge is a function of human cognition. The interrelation between language and meaning, including in evolutionary terms (as nicely studied by Terrence Deacon) involves, for Changeux, a ‘pooling of neuronal workspaces’ and a ‘contextualized sharing of representations’ (p. 113). Further to this, he argues that the scientific method is the most sophisticated embodiment of this cognitive faculty, along with freedom and communication. Changeux outlines the birth of the scientific method, from Aristotle to evolutionary biology, and argues that religion and mysticism are too readily open to the intellectual death of dogma. In contrast, the scientific method, with its fundamental basis on rationality is open to constant revision in the light of new evidence. He argues that it is time for scientists, especially those in the fields of neurobiology and cognitive science, to attempt to explain mythic thought. In fact, he argues, they have a ‘duty’ to do so in concert with those in the social sciences. Rationality is the order of the day, for without rationality we cannot find truth.

It is from here that Changeux moves onto the ‘humanity of science’, that is, the role that scientific progress has and can play in the struggle for society — both benign and otherwise. In exploring the implications of neuroscience and its relation to truth Changeux outlines what is essentially a humanitarian and personal view of how humans should relate to their social, cultural and physical surroundings. The overarching theme of his book — the relationship of knowledge as evolved in our brains to the world at large — leads to a passionate discussion of the intellectual and cultural repercussions of brain research. Using the scientific method as the pinnacle of human reason (and sounding like Comte, to whom he refers approvingly), Changeux argues that application of the method to society as a whole will promote the flourishing of individual rights and ideas of freedom. It is only within a society based on science and reason that stable agreement on truth can emerge. This is a positive and idealist view, and one Changeux believes is essential to the survival and happiness of humanity. It is unusual to find these sorts of reflections in a work of popular neuroscience, even one with large doses of theory included; by the end Changeux is sounding like a simpler version of Habermas.

This vision is painted on a large canvas, and as such the details can make the careful reader wince at times, whether it is a somewhat old-fashioned, almost Victorian vision of science, or an equally ahistorical sense of what philosophy is, how its arguments are articulated and how these may relate to empirical findings in the neurosciences. Changeux tends to flatten the differences between these ‘discourses’ or ‘ontologies’ onto one surface of Nature and creativity, as when Aristotle, Kant, Bergson or even Empedocles are presented as either having already grasped the correct solution to a neuroscientific problem or somehow stating it metaphorically — this is not to say that at times, such as with the synthetic unity of apperception and the ‘framing problem’, there are real interconnections. It simply doesn’t help to say that Hume’s model of the association of ideas is an early version of Hebb’s ‘strong’ or ‘weak’ links in neuronal connections (p. 198). Changeux also claims that ‘rationalism’ and ’empiricism’ are some sort of historical invariants which ‘reflect two distinct styles of functioning of the brain’ (p. 227) — a completely different approach which itself is left hanging.

The Physiology of Truth is at its core an attempt to naturalise the mythical (building on the work of Pascal Boyer), to explain the neurobiological basis for the fundamental tenets of what were once the domain of the spiritual — reason, freedom, truth and happiness. But this is still a field of research in its infancy. There is a lot of work to be done in both neuroscience and the social sciences before such an argument will be entirely convincing, especially to those with spiritual leanings.  It will certainly be interesting to see where further research in this field leads.

© 2010 Gemma Smart and Charles T. Wolfe

Gemma Smart (MA) and Charles T. Wolfe (PhD), Unit for History and Philosophy of Science, University of Sydney