In The Watchman’s Rattle, Rebecca Costa presents a view of the  parlous human condition with which I completely agree. The clash of religions, and civilizations, she argues, is not the cause of our difficulties but a consequence of them. The same is true of the global water shortage, climate change, the decline of carbon-based energy, our cheerful destruction of the remaining natural environment, and all the other calamities close to or upon us. The primary cause of all threatening trends is the complexity of civilization itself, which cannot be understood and managed by the cognitive tools we have thus far chosen to use.

We have come to this point, Ms. Costa tells us, because humanity lacks an adequate sense of its own history. We have not faced honestly the central questions of philosophy and religion, which are scrawled in simplest terms on the canvas of Paul Gauguin’s Tahitian masterpiece: Where did we come from? Who are we? Where are we going?

By history, Ms. Costa correctly means not just of this country or that, but of the rise and fall of past civilizations and, beyond, the six million years of biological evolution of the human line, played out in intricate relationship with the rest of the biosphere. From the long haul of biological evolution came genetic human nature. This period, during which we acquired our emotions and cognitive capacities, shrinks to an eyeblink the human history begun with the Neolithic revolution ten thousand years ago. The past three millennia have seen the exponentiation of everything gained by cultural evolution: population spread, the efficiency of work, knowledge, technology—and, unfortunately, the depletion of natural resources, the destruction of the remnant natural environment, and an increase in the war powers of more and more groups and nations.

Professional optimists like to say that doomsday predictions are as old as the written word and never come to pass. They believe that the genius and spirit of humanity have always found a way around its problems, and will again, and yet again. In short, not to worry. But to think this way is to ignore the reality of exponential change. If you have a doubling time of any entity or process of, say, twenty years, for a great many such periods the world as a whole will remain unsaturated and manageable. But at some point in any exponential growth, the next doubling time produces an absolute increase that overshoots all the space and resources left. At that point, the options for accommodation also shrink drastically. There is great truth in the oft-quoted riddle of the lily pads. A pond (a lake, an ocean, all apply) starts with a single lily pad. Each pad doubles per day; the pond will be full in thirty days. When is the pond only half full?  On the twenty-ninth day. After the next day, the thirtieth, further growth is so fast it will, if somehow continued, overwhelm the pond and everything in it in a matter of hours.

I am on the side of Rebecca Costa and others—let us accept the title of realists in search of a solution, not doomsayers—who say that be- cause of exponentiation, humanity doesn’t have a lot of time to figure things out. We have to solve our problems not by continuing to useemotions and responses that suited our primitive ancestors but now put us all in imminent danger. Instead, we need to use knowledge and reason and take an honest look at ourselves as a species. We need to grasp the increasing complexity of our social and political arrangements, and reach solutions. In The Watchman’s Rattle, Ms. Costa urges us to do so by employing the better instruments of our genetic nature.