Is western civilisation based on a mistaken understanding of humanity? Fundamental to any society is its comprehension of human nature. It shapes attitudes and policies on a whole range of issues: interpersonal relations, child-rearing, discipline and punishment, economics and welfare. For millennia western societies were based on the idea that human nature is flawed. This was turned upside down 300 years ago during the Enlightenment by writers such as Rousseau, who argued that we are born good and later warped by parents and society; a liberal view of human nature which is now being challenged by scientific discoveries in the fields of the mind, the brain, and genetics (including the Human Genome), evolutionary psychology, and anthropology.This fundamental change has had profound effects. If we are essentially good then we can safely maximize freedom and abandon morality, religion and tradition. Many aspects of life have been liberalised - sexual behaviour, alcohol consumption, censorship, gambling, divorce laws and economic activity. Economic liberals thought free markets were rational and good and favoured minimal government interference and light-touch regulations. This led to the credit crunch and the greatest financial crisis since World War Two.Many parents now hesitate to discipline their own children. The belief that we are essentially good but corrupted by society has also influenced penal policy. Liberals see criminals as victims, not as wrongdoers; because surely no-one would choose to do something wrong. This is a world far removed from the self-sacrifice and fraternity shown during World War Two. It has not brought happiness but rather more alienated individuals. The outcome of egalitarian aims or methods has often missed its mark: e.g., in education it has led to the dumbing down of academic standards, grade inflation and a decline in social mobility. Egalitarian regimes from the French Revolution to the Soviet era have been amongst the most bigoted, brutal and bloody in history. The drive for greater social justice and fairness must remain an essential objective. There is, therefore, an urgent need to separate out the positive from the negative aspects of liberal thought and practice, as otherwise there is the risk of descent into moral anarchy and social disintegration.