In a masterful synthesis of science and philosophy, one of the world's pre-eminent behavioural scientists demonstrates that free will is a powerful and dangerous illusion. The result is a new way to think about choice, identity, responsibility, justice, morality and how we live together.Behind every thought, action and experience there lies a chain of biological and environmental causes, stretching back from the moment a neuron fires to the dawn of our species and beyond. Nowhere in this infinite sequence is there a place where free will could play a role.Without free will, it makes no more sense to punish people for antisocial behaviour than it does to scold a car for breaking down. It is no one's fault they are poor or overweight or unsuccessful, nor do people deserve praise for their talent or hard work; 'grit' is a myth. This mechanistic view of human behaviour challenges our most powerful instincts, but history suggests that we have already made great strides toward where once we saw demonic possession or cowardice, for example, now we diagnose illness or trauma and offer help.Determined confronts us with our true who and what we are is biology and nothing more. Disturbing and liberating in equal measure, it explores the far-reaching implications for society of accepting this reality. Monumentally difficult as it may be, the reward will be a far more just and humane world.