Planet with a Purpose

If Earth is an organism getting ever more complex, doesn't that mean humans might have been made for a reason?

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The key to Dennett's change of view is the close connection between two separate questions: whether evolution has a purpose, and whether evolution has a direction. If you're going to believe, as that Anglican clergyman suggested, that a divine being set natural selection in motion, confident that it would eventually produce some species as intelligent as humans, then you have to believe that natural selection was likely to produce such intelligence from the beginning-that it was in this sense "directional".

On the question of directionality, Darwinians have long differed. Harvard biologist Edward O. Wilson considers intelligent life a likely product of natural selection; his late colleague Stephen Jay Gould argued otherwise. The evolution of creatures as smart as us was a fluke, Gould said, and its very unlikelihood was evidence that evolution had no purpose.

Before my dialogue with Dennett, his longstanding position had been that Gould was half wrong and half right: Natural selection


been fairly likely, sooner or later, to produce an intelligent species of some sort; but, no, this was not evidence that evolution had any overarching purpose, that natural selection was itself a product of design. Evolution had a direction of sorts, Dennett believed, but it definitely had no purpose.


But isn't this direction itself evidence of purpose? If a process naturally creates something as complex as great intelligence, doesn't that suggest the process was set up for that purpose? I've long thought so, but I had never been able to convince Dennett. He had read my book "Nonzero," whose closing chapters address this question, and had been unmoved. So I decided to take a new tack, with a new argument that drew on a famous incident in intellectual history.

The incident involves William Paley, a British theologian who wrote a book called "Natural Theology" in 1802, a few years before Darwin was born. In it he tried to use living creatures as evidence for the existence of a designer.

If you're walking across a field and you find a pocketwatch, Paley said, you know immediately that it's in a different category from the rocks lying around it. Unlike them, it is manifestly a product of design, featuring a complex functionality that doesn't just happen by accident. Well, he continued, organisms are like pocketwatches: they're too complexly functional to just happen by accident. So organisms must have a designer-namely, God.

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Robert Wright
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