Is the anthropic principle a fallacy?

Great Debates
1

If I were to tell you, “Ice floats on liquid water so that intelligent life can exist,” the fallacy is obvious. The universe, laws of physics, and all that good stuff can’t be assumed to serve any ultimate purpose.

But saying “If ice didn’t float on liquid water, we wouldn’t be around to notice” seems to me quite a different statement. Ice doesn’t float just so we can be here… but we’ll never see a universe where ice sinks.

It seems to me that the anthropic principle says nothing more than that our observations must add up to a universe that can support life, at the present moment. No matter how great the preponderance of odds against a life-supporting universe, we’ve only got the slim window of life-supporting possibilities to look at.

Big deal.

Or am I missing something here?

2

—But saying “If ice didn’t float on liquid water, we wouldn’t be around to notice” seems to me quite a different statement. Ice doesn’t float just so we can be here… but we’ll never see a universe where ice sinks.—

That’s not exactly the normal statement. Sort of the point is that if perhaps we COULD have been in a world in which ice sinks, then we could be there saying the exact opposite “ice doesn’t float so that intelligent can exist.” If such a universe couldn’t support life, we wouldn’t be around to comment on it. The whole point is that we wouldn’t be around to observe a universe in which intelligent life cannot/does not arise.

—Big deal.—

Sure: that’s the whole point. It’s about as trivial as: wherever you go: there you are.

3

To me, the anthropic principle is just the taking seriously of the old joke about God’s wisdom in placing holes in a cat’s skin at the exact place needed for its eyes to see out.

4

Consider the question of whether intelligent life exist on other planets. One might guess that since conditions on Earth were favorable to the development of life, then conditions are likely to have been equally favorable on lots of other planets.

However, the anthropic principle implies that even if life developed on only one planet ever, it would, of course, be ours.

In other words, the anthopic principle is a counter-argument to the idea of using probability calculations to prove the likeliness of ETI.

5

It all depends on your observation selection criteria. It can be meaningful, but only if your OS doesn’t a priori filter your data.

6

And: I couldn’t be here if there was no “here”.

7

Trivial? Your attitude might change if you ever go somewhere and end up somewhere else! :wink:

8

—Trivial? Your attitude might change if you ever go somewhere and end up somewhere else!—

But then I would be <I>there</I>! :slight_smile: