Steven Pinker is my primary reference in psychology. He makes scientific concepts engaging and memorable, and like Chomsky he equips readers to defend their beliefs with reason. How the Mind Works remains the standout account of how evolution shaped cognition, and Rationality lays out why reason is the essential driver of moral and social progress.
The Better Angels of Our Nature documents how much progress humanity has made: gradual, incomplete, and reversible if we let things slip. The incredible part is how many people refuse the evidence. Enlightenment Now continues the case, and its recognition of what markets have done shifted my earlier view, though I do not share his loftier regard for them. It also tends to overlook motives: its treatment of the weapons-of-mass-destruction rationale for the Iraq War and of Y2K panic attributes both to bias and ignores the profit motives that stoked them. George Monbiot has raised environmental objections to the book, and I wish Pinker would answer a journalist I take seriously.
My favorite line from Enlightenment Now: Martin Luther King Jr. said the arc of the moral universe is long but bends toward justice, and in the same spirit the arc of history bends toward progress, toward greater reason, knowledge, and well-being.