Enlightenment Now: The Case for Reason, Science, Humanism, and Progress

Other components of theistic morality, such as the existence of an immaterial soul and a realm of reality beyond matter and energy, are just as testable. We might discover a severed head that can speak. A seer could predict the exact day of natural disasters and terrorist attacks. Aunt Hilda could beam a message from the Great Beyond telling us under which floorboard she hid her jewelry. Memoirs from oxygen-starved patients who experienced their souls leaving their bodies could contain verifiable details unavailable to their sense organs. The fact that these reports have all been exposed as tall tales, false memories, overinterpreted coincidences, and cheap carny tricks undermines the hypothesis that there are immaterial souls which could be subject to divine justice.³⁴ There are, of course, deistic philosophies in which God created the universe and then stepped back to watch what happened, or in which “God” is merely a synonym for the laws of physics and mathematics. But these impotent Gods are in no position to underwrite morality.

Many theistic beliefs originated as hypotheses to explain natural phenomena such as the weather, disease, and the origin of species. As these hypotheses have been superseded by scientific ones, the scope of theism has steadily shrunk. But since our scientific understanding is never complete, the pseudo-argument known as the God of the Gaps is always available as a last resort. Today the more sophisticated theists have tried to place God into two of these gaps: the fundamental physical constants and the hard problem of consciousness. Any humanist who insists that we cannot invoke God to justify morality can expect to be confronted with these gaps, so let me say a few words about each. As we will see, they are likely to go the way of Zeus hurling thunderbolts as an explanation for electrical storms.

Our universe can be specified by a few numbers, including the strengths of the forces of nature (gravity, electromagnetism, and the nuclear forces), the number of macroscopic dimensions of space-time (four), and the density of dark energy (the source of the acceleration of the expansion of the universe). In Just Six Numbers, Martin Rees enumerates them on one hand and a finger; the exact tally depends on which version of physical theory one invokes and on whether one counts the constants themselves or ratios between them. If any of these constants were off by a minuscule iota, then matter would fly apart or collapse upon itself, and stars, galaxies, and planets, to say nothing of terrestrial life and Homo sapiens, could never have formed. The best-established theories of physics today don’t explain why these constants should be so meticulously tuned to values that allowed us to come into being (particularly the density of dark energy), and so, the theistic argument goes, there must have been a fine-tuner, namely God. It is the old Argument from Design applied to the entire cosmos rather than to living things.

An immediate objection is the equally old problem of theodicy. If God, in his infinite power and knowledge, fine-tuned the universe to bring us into being, why did he design an Earth on which geological and meteorological catastrophes devastate regions inhabited by innocent people? What is the divine purpose of the supervolcanoes that have ravaged our species in the past and may extinguish it in the future, or the evolution of the Sun into a red giant that will do so with certainty?

But theodical speculation is beside the point. Physicists have not been left dumbstruck by the apparent fine-tuning of the fundamental constants, but are actively pursuing several explanations. One is captured in the title of the physicist Victor Stenger’s book The Fallacy of Fine-Tuning.³⁵ Many physicists believe that it’s premature to conclude that the values of the fundamental constants are either arbitrary or the only ones consistent with life. A deeper understanding of physics (particularly the long-sought unification of relativity and quantum theory) may show that some of the values must be exactly what they are. Others, we might learn, could take on other values—more important, combinations of values—that are compatible with a stable, matter-filled universe, albeit not the one we know and love. Progress in physics may reveal that the constants are not so finely tuned, and a life-supporting universe not so improbable, after all.