Today humanity is reaching new heights of scientific understanding - and also appears to be losing its mind. Steven Pinker rejects the cynical clich e that humans are simply irrational. Pinker explores how the rational pursuit of self-interest, sectarian solidarity, and uplifting mythology can add up to crippling irrationality in a society. Collective rationality depends on norms that are explicitly designed to promote objectivity and truth. Rationality leads to better choices in our lives and in the public sphere, and is the ultimate driver of social justice and moral progress