When Galileo attracted the unwanted attention of the Inquisition in 1633, more was at stake than issues in astronomy. By stating that the Earth revolved around the sun rather than vice versa, Galileo was contradicting the literal truth of the Bible, such as the passage in which Joshua issued the successful command “Sun, stand thou still.” Worse, he was challenging a theory of the moral order of the universe.

According to the theory, developed in medieval times, the sphere of the moon divided the universe into an unchanging perfection in the heavens above and a corrupt degeneration in the Earth below (hence Samuel Johnson’s disclaimer that he could not “change sublunary nature”). Surrounding the moon were spheres for the inner planets, the sun, the outer planets, and the fixed stars, each cranked by a higher angel. And surrounding them all were the heavens, home to God. Contained within the sphere of the moon, and thus a little lower than the angels, were human souls, and then, in descending order, human bodies, animals (in the order beasts, birds, fish, insects), then plants, minerals, the inanimate elements, nine layers of devils, and finally, at the center of the Earth, Lucifer in hell. The universe was thus arranged in a hierarchy, a Great Chain of Being.

The Great Chain was thick with moral implications. Our home, it was thought, lay at the center of the universe, reflecting the importance of our existence and behavior. People lived their lives in their proper station (king, duke, or peasant), and after death their souls rose to a higher place or sank to a lower one. Everyone had to be mindful that the human abode was a humble place in the scheme of things and that they must look up to catch a glimpse of heavenly perfection. And in a world that seemed always to teeter on the brink of famine and barbarism, the Great Chain offered the comfort of knowing that the nature of things was orderly. If the planets wandered from their spheres, chaos would break out, because everything was connected in the cosmic order. As Alexander Pope wrote, “From Nature’s chain whatever link you strike, / Tenth, or ten thousandth, breaks the chain alike.” 1

None of this escaped Galileo as he was pounding away at his link. He knew that he could not simply argue on empirical grounds that the division between a corrupt Earth and the unchanging heavens was falsified by sunspots, novas, and moons drifting across Jupiter. He also argued that the moral trappings of the geocentric theory were as dubious as its empirical claims, so if the theory turned out to be false, no one would be the worse. Here is Galileo’s alter ego in Dialogue Concerning the Two Chief World Systems, wondering what is so great about being invariant and inalterable:

For my part I consider the earth very noble and admirable precisely because of the diverse alterations, changes, generations, etc. that occur in it incessantly. If, not being subject to any changes, it were a vast desert of sand or mountain of jasper, or if at the time of the flood the waters which covered it had frozen, and it had remained an enormous globe of ice where nothing was ever born or ever altered or changed, I should deem it a useless lump in the universe, devoid of activity and, in a word, superfluous and essentially nonexistent. This is exactly the difference between a living animal and a dead one; and I say the same of the moon, of Jupiter, and of all other world globes.

. . . Those who so greatly exalt incorruptibility, inalterability, et cetera, are reduced to talking this way, I believe, by their great desire to go on living, and by the terror they have of death. They do not reflect that if men were immortal, they themselves would never have come into the world. Such men really deserve to encounter a Medusa’s head which would transmute them into statues of jasper or diamond, and thus make them more perfect than they are. 2

Today we see things Galileo’s way. It’s hard for us to imagine why the three-dimensional arrangement of rock and gas in space should have anything to do with right and wrong or with the meaning and purpose of our lives. The moral sensibilities of Galileo’s time eventually adjusted to the astronomical facts, not just because they had to give a nod to reality but because the very idea that morality has something to do with a Great Chain of Being was daffy to begin with.

We are now living, I think, through a similar transition. The Blank Slate is today’s Great Chain of Being: a doctrine that is widely embraced as a rationale for meaning and morality and that is under assault from the sciences of the day. As in the century following Galileo, our moral sensibilities will adjust to the biological facts, not only because facts are facts but because the moral credentials of the Blank Slate are just as spurious.

This part of the book will show why a renewed conception of meaning and morality will survive the demise of the Blank Slate. I am not, to say the least, proposing a novel philosophy of life like the spiritual leader of some new cult. The arguments I will lay out have been around for centuries and have been advanced by some of history’s greatest thinkers. My goal is to put them down in one place and connect them to the apparent moral challenges from the sciences of human nature, to serve as a reminder of why the sciences will not lead to a Nietzschean total eclipse of all values.

The anxiety about human nature can be boiled down to four fears:

• If people are innately different, oppression and discrimination would be justified.
• If people are innately immoral, hopes to improve the human condition would be futile.
• If people are products of biology, free will would be a myth and we could no longer hold people responsible for their actions.
• If people are products of biology, life would have no higher meaning and purpose.

Each will get a chapter. I will first explain the basis of the fear: which claims about human nature are at stake, and why they are thought to have treacherous implications. I will then show that in each case the logic is faulty; the implications simply do not follow. But I will go farther than that. It’s not just that claims about human nature are less dangerous than many people think. It’s that the denial of human nature can be more dangerous than people think. This makes it imperative to examine claims about human nature objectively, without putting a moral thumb on either side of the scale, and to figure out how we can live with the claims should they turn out to be true.