Wednesday, August 26, 2009

The Fine-Tuning argument (part 2)

See part 1

Here is the Fine-Tuning argument, restated... in limerick form?
Many constants of nature, I'm told,
If changed, would leave the world cold,
But a being divine
Would tune them all fine,
Without God, they'd be uncontrolled.
Don't ever expect me to write poetry again.

If you asked me why I disagree with the Fine-Tuning argument, and if I had enough time and space to explain it (ie here and now), I would begin by pointing to this article by Michael Ikeda and Bill Jefferys. They show, using bayesian reasoning and mathematics, that the Fine-Tuning cannot possibly succeed. If anything, the Fine-Tuning argument shows precisely the opposite of what it attempts to show. You might find this quite shocking. I know I did. Though I thought it was a poor argument, even back in my Catholic high school days, I never imagined that it was entirely backwards.

The first key point is the Weak Anthropic Principle. Ikeda and Jefferys state the WAP as follows: If life exists, and if the world is governed by natural law, then those natural laws are "life-friendly", meaning that they allow for life to possibly exist.

The second key point: What happens if we observe that the natural laws are in fact not life-friendly at all? This implies something supernatural, perhaps a god, or perhaps something else. You might say, in a way, that this is the argument of Intelligent Design. They argue that natural laws, such as natural selection, could not possibly lead to the diversity of life as we know it. That is, they argue that our world is not life-friendly to us. Therefore, the supernatural must exist.

And finally, what happens if we observe that the natural laws are life-friendly? The Fine-Tuning argument would have you believe that this is strong evidence for a god. A life-friendly world is unlikely to exist given a world governed by natural laws, so goes the argument. Therefore, the world is unlikely to be governed by natural laws, given that it is life-friendly.

But if you've been paying close attention, you'd realize that we're falling for the fallacy of having it both ways. The claim now suffers the problem of being unfalsifiable. If the natural laws are not life-friendly, the supernatural must exist. If the natural laws are life-friendly, the supernatural probably exists. No matter what we observe, life-friendly or not, you could conclude that the supernatural probably exists.

That is to say, given your new observation, God is more likely than before your observation. But you already know, before you have made any observations at all, that the world is either life-friendly or not. Therefore, before you observe anything, God is more likely than before you observe anything. It's a logical contradiction. When we encounter contradiction, we have to back up, and question our original assumptions. Our most questionable assumption was that the Fine-Tuning argument is valid. This assumption was incorrect. The only way to resolve the contradiction is by saying that the Fine-Tuning argument is either evidence against the supernatural, or it is neutral.

And that's the basic idea of Ikeda and Jefferys argument. Except they use more bayesian reasoning and math, which is always cool. I would have liked to explain it mathematically myself, but they do it better. It is worth a read.


DarkSapiens said...

Reading Ikeda and Jefferys article took time, but it was worth it. I had never seen this from that point of view!

I like the part when they prove that the only way to prevent a life-friendly universe to support naturalistic laws instead of the supernatural means that those two would be indistinguishable, and therefore proposing the supernatural to explain the world is absolutely unnecessary.

By the way, is it just me or the WAP is too obvious that it isn't even necessary to be enunciated? I mean, if it states that "If life exists, and if the world is governed by natural law, then those laws permit the existance of life", it seems a tautology to me… unless you appeal to "supernatural ways" to put life here. Is that the point, or am I missing something?

miller said...

You're right, it is somewhat tautological. I suppose it's just one of those things which seems totally obvious only after you explicitly state it.