The doctrines of the Blank Slate, the Noble Savage, and the Ghost in the Machine--or, as philosophers call them, empiricism, romanticism, and dualism--are logically independent, but in practice they are often found together.

The mind cannot be a blank slate, because blank slates don't do anything.

Universal mental mechanisms can underlie superficial variation across cultures.

Behavior is not just emitted or elicited, nor does it come directly out of culture or society. It comes from an internal struggle among mental modules with differing agendas and goals.

One can say that the information-processing activity of the brain causes the mind, or one can say that it is the mind, but in either case the evidence is overwhelming that every aspect of our mental lives depends entirely on physiological events in the tissues of the brain.

The conscious mind--the self or soul--is a spin doctor, not the commander in chief. Sigmund Freud immodestly wrote that "humanity has in the course of time had to endure from the hands of science three great outrages upon its naïve self-love": the discovery that our world is not the center of the celestial spheres but rather a speck in a vast universe, the discovery that we were not specially created but instead descended from animals, and the discovery that often our conscious minds do not control how we act but merely tell us a story about our actions.

The phenomena we call "culture" arise as people pool and accumulate their discoveries, and as they institute conventions to coordinate their labors and adjudicate their conflicts.

Reductionism, like cholesterol, comes in good and bad forms. Bad reductionism--also called "greedy reductionism" or "destructive reductionism"--consists of trying to explain a phenomenon in terms of its smallest or simplest constituents. Good reductionism (also called hierarchical reductionism) consists not of replacing one field of knowledge with another but of connecting or unifying them.

When a person suffers neurological damage, the healthy parts of the brain engage in extraordinary confabulations to explain away the foibles caused by the damaged parts (which are invisible to the self because they are part of the self) and to present the whole person as a capable, rational actor.

For all their flaws, liberal democracies appear to be the best form of large-scale social organization our sorry species has come up with so far. They provide more comfort and freedom, more artistic and scientific vitality, longer and safer lives, and less disease and pollution than any of the alternatives. Modern democracies never have famines, almost never wage war on one another, and are the top choice of people all over the world who vote with their feet or with their boats.

Equality is not the empirical claim that all groups of humans are interchangeable; it is the moral principle that individuals should not be judged or constrained by the average properties of their group.

Here are the three laws:

• The First Law: All human behavioral traits are heritable.

• The Second Law: The effect of being raised in the same family is smaller than the effect of the genes.

• The Third Law: A substantial portion of the variation in complex human behavioral traits is not accounted for by the effects of genes or families.

The laws are about what make us what we are (compared with our compatriots) and thus they are about the forces that impinge on us in childhood, the stage of life in which it is thought that our intellects and personalities are formed.

As long as the heritability of talents and tastes is not zero, none of us has any way of knowing whether a trait has been influenced by our genes, our childhood experiences, both, or neither.

A handy summary of the three laws (of nature vs nurture) is this: Genes 50 percent, Shared Environment 0 percent, Unique Environment 50 percent (or if you want to be charitable, Genes 40–50 percent, Shared Environment 0–10 percent, Unique Environment 50 percent). A simple way of remembering what we are trying to explain is this: identical twins are 50 percent similar whether they grow up together or apart. Keep this in mind and watch what happens to your favorite ideas about the effects of upbringing in childhood.