As you might expect, the anthropic principle has provoked a huge debate and a strong reaction. In this debate there are three positions, which for simplicity I call Lucky Us, Multiple Universes, and the Designer Universe. Let’s examine them in sequence. The first response, Lucky Us, attributes the fine-tuning of the universe to incredible coincidence. “The universe,” writes physicist Victor Stenger in Not By Design, “is an accident.”

An accident? Steven Weinberg and Richard Dawkins are not impressed by how improbable this is. According to Steven Weinberg, “You don’t have to invoke a benevolent designer to explain why we are in one of the parts of the universe where life is possible: in all the other parts of the universe there is no one to raise the question.” Richard Dawkins concurs. “It is no accident that our kind of life finds itself on a planet whose temperature, rainfall, and everything else are exactly right. If the planet were suitable for another kind of life, it is that kind of life that would have evolved here.” In science this is called a “selec- tion effect:’ Since we are here, we know that—whatever the odds—the game of cosmic chance must have worked out in our favor.

There is a problem with this reasoning that I’d like to dramatize by giving an example from philosopher John Leslie. Imagine a man sentenced to death, standing before a firing squad of ten shooters. The shooters discharge their rifles. Somehow they all miss. Then they shoot again and one more time they fail to hit their target. Repeatedly they fire and repeatedly they miss. Later the prisoner is approached by the warden, who says, “I can’t believe they all missed. Clearly there is some sort of conspiracy at work.” Yet the prisoner laughs off the suggestion with the comment, “What on earth would make you suggest a conspiracy? It’s no big deal. Obviously the marksmen missed because if they had not missed I would not be here to have this discussion.” Such a prisoner would immediately, and rightly, be transferred to the mental ward.