Brian Greene - Why Is Our Universe Fined-Tuned for Life?

Have you noticed that wherever Brian Greene goes, computer animations go with him? Well, this TEDTalk presentation is no exception :) I'm starting to wonder whether this might be the physicist equivalent of a comfort blanket...

In any case, and as you may expect if you're familiar with him, he lays down the case for string theory, and explains some of the fascinating implications if string theory and the cosmological theory of inflation were true. Even as mere hypothetical possibilities, these ideas merit our attention.

What I do have a major problem with, however, is his "explanation" for why our universe is fine-tuned for life. It's a version of the anthropic principle that is either completely backwards or completely question-begging (circular)... or both... I'll let you be the judge:


The analogy with our distance to the sun doesn't quite work because, despite his explicit claim to the contrary, it's asking one question but answering another. Our distance to the sun doesn't explain why Earth is  x-number of miles away from the sun (see what I mean by circular?). It doesn't tell us anything about astronomy or physics.

What it explains is why we live on Earth and get to ask that question, but it tells us nothing about the conditions that led to our planet being where it is... Similarly, the fact that we happen to inhabit the particular kind of universe that contains the conditions that allow for life-forms such as ours tells us nothing about why this particular universe happens to have those particular features.

In other words, you can't answer the question of why is our universe fine-tuned for life by answering that it's because our universe is fine-tuned for life... or am I missing something here?