The End of the World: The Science and Ethics of Human Extinction

John Leslie is a professor of philosophy at the University of Guelph. Much of this book is taken up with explorations of, criticisms of, and defences of the 'Doomsday Argument', championed by Leslie and cosmologist Brandon Carter. The 'Doomsday Argument' goes something like this: -if humanity were to continue to prosper and multiply, eventually spreading beyond the solar system, and perhaps the galaxy, the total number of human beings today (6 billion) will seem insignificant compared to the potential trillions and trillions of humans in the future. But if this were to actually happen, humans today would be among the very earliest of the race -perhaps in the first 0.1 per cent or even 0.001 per cent. How likely is it that we are that special? In the year 2090 the population of earth might be 12 billion people. Of all the humans who had ever lived, one in ten would be alive in that year. Instead of expecting to be in a remarkably early stage of human civilization, say in the first 0.1 per cent, it is much more likely that an inhabitant of the year 2090 will be among that 1 in 10 present when humanity died. To me this argument seems flimsy, sophistic, and somehow just wrong, but Leslie does an impressive and thorough job of refuting the many objections to it. My eyes glazed over during some of these detailed and convoluted defences, but then I only took one philosophy course in university. What I liked this book for was the exploration of the many delicious ways in which humanity could be wiped out. Some of these faces of doom might seem quite far-fetched and unlikely, but all have some formidable scientists and philosophers backing them. Here is an abbreviated list: -nuclear war. "Small nations, terrorists, and rich criminals wanting to become still richer by holding the world to ransom, can already afford very destructive bombs." Suitcase bombs in particular worry me. I believe a few well-placed bombs could de-stabilize the United States almost overnight. -biological warfare. Such weapons are less costly than nuclear weapons, easier to conceal, and could be more dangerous because their field of destruction is harder to limit. -chemical warfare. -destruction of the ozone layer. "...by chlorofluorocarbons or other things." -'Greenhouse effect'. "On Venus, greenhouse effect temperatures are sufficient to melt lead." -poisoning by pollution. "Hundreds of new chemicals enter the environment each year. Their effects are often hard to predict." -disease. Many deadly diseases are developing immunity to our best drugs. New viruses are thought to filter down from outer space. Global warming could thaw out some virulent disease from the past, such as the 1918-1919 flu, which preferred younger, healthy victims. ("They died horribly, their lungs filling with fluid, becoming stiff and solid, literally drowning them. As they expired, they vented pints of the highly infectious liquid from their mouths and noses." -Calgary Herald, O

Some of the reviews below miss the point of John Leslie's book. Professor Leslie is a utilitarian philosopher at the University of Guelph in Ontario, and as such he's written this book with the express objective of providing a warning to civilization of the dangers that lie ahead. In spite of what the book's title may initially suggest, the book is not the work of some gloomy apocalyptic doomsayer; rather, it is a sensible consideration of the perils that an advanced civilization like our own must overcome over the next crucial period to advance. It's easy to simply take civilization for granted, but Leslie's point is that its survival is not guaranteed, but depends on the choices that we make in the near future. Prof. Leslie asserts that if humanity can make it past the next few centuries then civilization will be in fairly good shape; it's the period soon to be upon us that will be so rocky, with dangers in everything from the spread of nuclear weapons to the practice of biological warfare, from impacting asteroids to poorly thought-out particle physics experiments gone awry, from chemical weapons to the biggest threat of all-- the destruction of earth's fragile ecosystem upon which we all rely, but so often do not recognize. What Leslie is calling for is wisdom, and for the practice of restraint and discipline on a societal scale, to avoid the petty squabbles and foolish waste of resources that we can no longer afford. Admittedly some of the methodology used in the book is flawed and has been shown to be problematic, but this does not belittle its value. The book suggests that it's time to "shape up" and to put into practice, those qualities associated with "higher functioning" and a truly advanced society, and to recognize the dangers ahead of time-- thus applying foresight and planning far ahead for crises, and averting them in the first place. The book is therefore an excellent "wake-up call" to move us out of complacency, and for this reason alone it is quite valuable.

The reviewer below misses the thrust of Leslie's argument. Initially, in the first two chapters of the book, he sets out to list ALL of the ways through which society could become extinct (a notion that has not been held in high esteem for policymaking relevance, anyway, in modern society). As such, he does borrow a lot from other authors. And, adding in, his lifting of the mathematical equation suggesting that we are near the end of 'our' time on the Earth makes mathematical sense, even if being totally anthropomorphic.... And the case is made, if you let it be, that we should probably start thinking about how we are going to 'go', and plan thereof....Aside from that, this book is a riot. The first two chapters, though morbid, are a laugh. The book (setting aside the good philosophy) should be read just for the initial paranoia. It's all in good fun....

This is a fleshing out of the basic idea sketched by richard gott in the magazine "Nature" in 1993. If one accepts the idea that one's placement in time is random, as is one's place in space, the implication is that no one can legitimately claim that an extremely "long future" scenario for the human race (a la Star Trek) seems likely. The reason, simply put, is that that scenario would make one's present placement in time extremely special; in the first 0.000001 % of humans who will ever live. The copernican priniciple of non-specialness holds for both space and time, given their equivalence, united as spacetime.

Being tremendously interested in the end of the world (from a sociology standpoint) I immediately devour any books on catastrophism, eschatology or millenialism. What John Leslie offers here is something quite different than the run-of-the-mill babbling on possible scenarios. He looks at the likely(and not so likely) events which may trigger "the end"; somewhat similar to Asimov's approach in his 70's non-fic A CHOICE OF CATASTROPHES. Leslie takes us a little deeper into the complexities of these situations by examining the true risks and consequences involved, all the while maintaining a solid scientific objectivity. All this would make for a great book alone, but Leslie goes further. He has the courage to explore the idea that perhaps we are arrogant in assuming we can control our fate as a species (hence the ETHICS portion of the book title) and maybe we have lost (or never had) the necessary objectivity we need to endure. A truly fascinating book about something the average human being doesn't (but should) think about. Kudos to John Leslie for putting humans where they belong in the scheme of the universe: the tiny little box marked "naked & vulnerable"!