Letter: Genes only give us potential

Colin Tudge calls for the "testing of testable hypotheses" in studying behaviour ("Outrage at violence is the easy way", 14 July). But, counter to his social Darwinism, no genes have yet been found that code for anything as complex as altruism and violence. Besides, all that genes give us are capacities. Whether and how these are developed depends on the environment we interact with and create.

An Aristotelian approach to human nature and ethics looks for realisable capacities in behaviour as a basis for working out the necessary conditions of human flourishing. This avoids the grave flaws of the Darwinian model - its "just so" stories, beloved by free marketeers, whereby any trait is "good" because it is assumed to have served some function conducive to the survival of its bearer.

If Colin Tudge is right that psychology and sociology are arid, the reason is that they are trapped in an underlying framework which has reached its limits, and lack the conceptual coherence, insights and interdisciplinary links to transform it into a more perceptive, expansive and virtuous one.

David Rodway

London SW1