What kind (if any) of fallacy is present in this argument?

For a creationism debate, one makes the argument that the universe has to be fine-tuned with all these precise living conditions that make life on earth possible (climate, we’re X distance away from the sun etc.).

Doesn’t this argument pose some kind of logical fallacy, simply because if conditions weren’t “perfect,” we wouldn’t be here in the first place to marvel about how “finely tuned” the universe is? Is there a term for this kind of backwards-thinking (or putting the cart before the horse, so to speak)?

I don’t know the official term for the fallacy, but it is like a puddle marvelling that the ground under it is the perfect shape to fit it. Life fits the Earth because it grew up on the Earth. If we live somewhere else, we would match those conditions perfectly.

The principle is called the anthropic principle, and as you’re phrasing it, it’s a tautology.

Or if you’re not willing to accept the anthropic principle (and many aren’t) you could argue that this is a simple god of the gaps argument. “We don’t know why those variables are the way they are”* does not imply “god did it”.

  • ETA: And as far as I know, nobody really knows what values they could possibly have either, so we really don’t know much about what could happen if the variables were all completely different or what the consequences would be as far as intelligent life is concerned.

There are certain physical constants that appear to be fine tuned to allow the existence of matter, stars etc, and thus life as we know it.

http://en.wikipedia.org/wiki/Fine-tuned_Universe

All the anthropic principle really says is that if it were otherwise, we wouldn’t be around to notice it. This would mean something if there were lots of other universes with different physical constants, but we don’t have any evidence for that. The apparent fine tuning is the strongest argument i’ve heard for the existence of some sort of creator, although there are other possible explanations.

Note it doesn’t support the usual creationist viewpoint of earth being created 6000 years ago by god, nor does it refute evolution, big bang theory etc.

The error being made here is the supposition that the universe was made for us, because we’re in it. They are reversing the normal conclusion because of their preconceived religious beliefs. They are like the water in a puddle that decides the hole must have been made just for it, cuz look, it happens to be exactly the right shape. When, of course, it was us who adapted to the conditions of the universe/world to make us who we are today.

A recent article in Scientific American (Jan '10) by Alejandro Jenkins and Gilad Perez addressed this. The authors pointed out that although many individual constants have narrow ranges allowing life as we know it, different combinations of constants could compensate for each other in ways that would allow the existence of complex nuclei that could form the basis of life. (For example: Any stable group of subatomic particles with a total of six positive charges would be equivalent to carbon, even if it wasn’t the familar carbon-12 of our universe).

And that’s just for “life as we know it”. It’s also possible that there might be some form of life that’s entirely gravitational, say, and would only exist on scales of millions of lightyears (and live much more slowly than us, of course). Or life based on the strong nuclear force, that lives on the surface of neutron stars. Or maybe if the constants were some other just-so, there’d be entirely different forces that don’t show up in our Universe at all, but which could be the basis for life in universes where they do exist.

We don’t really have any evidence against the existence of other universes, either. Absence of evidence is not proof of anything. Also, consider the vastness of this universe and the astronomical number of planets within-most of which, if the local examples are trustworthy indicators, can not support life as we know it. With numbers that high, the existence of a couple of spots that managed to sprout lifeforms that could thrive in those environs doesn’t seem all that impressive, more like what you would expect from a chance roll of the trillion-sided dice.

Countless universes may exist that do not support life in the way that this universe does. Of course, that means there are no sentient beings in those universes wondering why God made a mistake in creating a universe that they could not live in. :rolleyes:

Suppose that countless universes exist and ALL of them feature earth-like planets which are seemingly ‘fine-tuned’ to support human(and elephant and goat and amoeba and horseshoe crab and whatever)-like creatures. Why can’t I use this hypothetical fact as a reason to suspect that there is NO designer? If I see one venus flytrap that has caught a fly, I might assume, having never seen one before, that someone or thing put the fly in its ‘mouth’ for it. But if I see several, I may conclude that venus flytraps naturally tend to catch flies and do not need assistance to do so. So, maybe universes made of the stuff ours is made of just naturally tend, due to their structure, to produce planets with the right range of variables for life as we know it (or, universes like ours tend to produce organic matter capable of adapting itself to the environs).

That’s the whole point of the question: Why does the Universe have the particular structure it does? We’re not talking about trivial variables like how far a planet is from its star, or the mass of a planet: Those certainly vary within the Universe, and it’s no surprise that we happen to find ourselves on a planet that is suited to life in those regards. The real question is about things like the ratios of masses of subatomic particles, or the strengths of the fundamental forces. Those certainly do not appear to vary within our Universe, and it’s an open question whether they might vary across other, hypothetical universes, so it’s not quite so easy to say “Of course we happen to live in one of the universes where life is possible”, since it still avoids the question of why there should be any universe(s) where life is possible.

You may also be interested in This talk by Dr. Paul Davis “the origin of the laws of physics” (streaming video, about an hour long).

I thought the question was, Does the following constitute a logical fallacy: supposing that a universe wherein a planet which exists within the precarious ‘Goldie Locks’ range suitable for sustaining life must necessarily have been designed (since the range is so small and sensitive as to seem unlikely to have come about without the intent of a sentient creator). And I say, yes, it is a fallacy, because that fact does not constitute evidence that the existence of such a creator is any more probable than it would be if this were not the case.

However, I guess if one wants to show that this reasoning is illogical, the next step would be to come up with a reason for why the universe is this way (life-sustaining in some places) and not some other way. I just have a problem with this kind of thinking because if we are going to wonder why the universe isn’t some other way–well, there are an infinite number of realities that are not (apparently) extant. Why should there be a reason for any one kind of reality over another? Isn’t this idea that there are always answers to questions a man-made one? To us, the fact that our world can sustain life is a Big Fat Deal, because we have evolved to care deeply about things like being alive and conscious. But the importance of life is just an adaptive thought, and all the other particles in the universe could really give a damn.

You and others have pointed out one logical issue–that we can only ask that question because we’re here, because reality came out as it did.

I will put the question in a simpler context, to make another part of the fallacy more obvious. (courtesy of an example from the great Richard P. Feynman. (both attribution and details may be imperfect—I don’t have the book in front of me have updated the numbers–but neither changes the point).

At 8.30 this morning, on my way to work, I saw a car with the license plate 5AB1234.

Think of the odds of that! There are 7.5 million registered vehicles in the Los Angeles area alone. What were the odds of that?

Now, and this is the key–it points out the fallacy what would the odds have been had Feynman named the plate number first, and then walked to work?

The point being, of course, the odds are 7.5 million to one (or billions, or trillions, or whatever) BEFORE one option is selected. One option was selected–the probability of seeing 5AB 1234 was, of course, 1 at 9am–since it was, in fact, seen.

So first of all, the fact that there are a lot of unlikely alternatives doesn’t mean that we should be surprised when one option is selected. That’s like walking into a room to watch someone throw darts blindfolded, finding out that he’s already done it, and seeing tiny circles drawn around the places where they landed.

Sure, it would be amazing if he drew the circles first, and then threw the darts blindfolded. Is it as amazing if he drew the targets around the places where the darts hit?

More importantly, the probability of “randomness” reaching one result, on its own, doesn’t prove anything. The necessary (and ignored) question is whether the probability of the car being there BY DESIGN is greater than that of random chance.

So to return to the example: is the fact that Feynman saw 5AB 1234 proof that it was put on that street so that he’d see it? Even if a process isn’t “random” (i.e. which license plate is likely to be in which part of California at 8.30 in the morning), to think the vehicle was there SO THAT a physicist would see it on his way to work is just plain less likely than the fact that there had to be some car there, and this morning, it happened to be this one.

Or, (missed the edit window)–to frame the point more expressly in the language of conditional probability (for that is the issue we’re talking about here):

The fallacy is in the difference between asking:

Given that there are 7.5 million registered vehicles in LA, what are the odds I will see license plate 5AB1234 this morning?

and

Given that I saw license plate 5AB1234 this morning, what were the odds that I would see license plate was 5AB1234 this morning?

To oversimplify by reducing the odds of seeing a given license plate to equal probabilities, the answer to the first question is 1: 7,500,000. The answer to the second question is, of course, 1. It is shocking and amazing if you predict the first one. What asserting the second one tells us, I leave as a rhetorical question.

[QUOTE=whorfin

At 8.30 this morning, on my way to work, I saw a car with the license plate 5AB1234.

Think of the odds of that! There are 7.5 million registered vehicles in the Los Angeles area alone. What were the odds of that?

Now, and this is the key–it points out the fallacy what would the odds have been had Feynman named the plate number first, and then walked to work?

The point being, of course, the odds are 7.5 million to one (or billions, or trillions, or whatever) BEFORE one option is selected. One option was selected–the probability of seeing 5AB 1234 was, of course, 1 at 9am–since it was, in fact, seen.

So first of all, the fact that there are a lot of unlikely alternatives doesn’t mean that we should be surprised when one option is selected. That’s like walking into a room to watch someone throw darts blindfolded, finding out that he’s already done it, and seeing tiny circles drawn around the places where they landed.

Sure, it would be amazing if he drew the circles first, and then threw the darts blindfolded. Is it as amazing if he drew the targets around the places where the darts hit?

More importantly, the probability of “randomness” reaching one result, on its own, doesn’t prove anything. The necessary (and ignored) question is whether the probability of the car being there BY DESIGN is greater than that of random chance.

So to return to the example: is the fact that Feynman saw 5AB 1234 proof that it was put on that street so that he’d see it? Even if a process isn’t “random” (i.e. which license plate is likely to be in which part of California at 8.30 in the morning), to think the vehicle was there SO THAT a physicist would see it on his way to work is just plain less likely than the fact that there had to be some car there, and this morning, it happened to be this one.[/QUOTE]

This is a better articulation of the exact point I was trying to make in my last post, when I said that there are an infinite number of possible realities. We are inclined to think that this particular reality is impressive because it includes us. But it is no more or less special than realities that would not include our existence. Another way to illustrate it: of all the sperm that could have reached the egg that was the precursor to me, the one that made it was the exact one that could create me and not someone else. But I don’t go around thinking, ‘well, obviously someone MEANT for me in particular to be born, because it was so unlikely yet happened anyway.’ Everyone is unlikely!