[asa] Critique of anthropic principle

From: Jon Tandy <tandyland@earthlink.net>
Date: Mon Apr 21 2008 - 10:55:53 EDT

The anthropic principle, and alternately the talk.origins site, are
regularly thrown out on this list in response to various questions. So I
thought I would post what talk.origins has to say about the anthropic
principle, to get some feedback. I have some thoughts on some of these
[which are bracketed below in red], but I'm curious how others would respond
to these critiques of the anthropic principle, since this is widely held to
be a significant evidence for a theistic view.
Claim CI301: (http://www.talkorigins.org/indexcc/CI/CI301.html)

The cosmos is fine-tuned to permit human life. If any of several fundamental
constants were only slightly different, life would be impossible. (This
claim is also known as the weak anthropic principle.)


1. The claim assumes life in its present form is a given; it applies not to
life but to life only as we know it. The same outcome results if life is
fine-tuned to the cosmos.

We do not know what fundamental conditions would rule out any possibility of
any life. For all we know, there might be intelligent beings in another
universe arguing that if fundamental constants were only slightly different,
then the absence of free quarks and the extreme weakness of gravity would
make life impossible.

[This seems to be an argument from ignorance. There might be other
intelligent beings and might be other universes, but the counter-argument
fails for lack of any evidence.]

Indeed, many examples of fine-tuning are evidence that life is fine-tuned to
the cosmos, not vice versa. This is exactly what evolution proposes.

[I don't understand this argument, and it's simply given as an assertion.
How is life fine-tuned for the universe, and what does this have to do with


2. If the universe is fine-tuned for life, why is life such an extremely
rare part of it?

[Again, an argument from ignorance, since we don't know whether or not there
is life in any other solar system, or even on any other planet. It may have
relevance since we don't think there is life elsewhere in our solar system,
but we are such a small part of the universe, I don't see this as a credible


3. Many fine-tuning claims are based on numbers being the "same order of
magnitude," but this phrase gets stretched beyond its original meaning to
buttress design arguments; sometimes numbers more than one-thousandfold
different are called the same order of magnitude (Klee 2002).

How fine is "fine" anyway? That question can only be answered by a human
judgment call, which reduces or removes objective value from the anthropic
principle argument.

[This seems to be a fair criticism if true, but what I've read of the fine
tuning arguments is that only fractionally slight variations in the
fundamental constants would cause significant problems for the current
structures necessary for life. I think this is a good point, because how do
we really know that the universe or other universes couldn't produce life
with completely different sets of fundamental constants? And if we ever
could find that other structurally different universes could still produce
life, we would probably revise the anthropic principle to say that "God has
designed matter/universe to bring forth life, even under radically different
initial conditions and laws." In this respect, I can see the "anthropic
principle" as more of a philosophical argument than a scientific principle,
because it seems difficult or maybe impossible to falsify.]


4. The fine-tuning claim is weakened by the fact that some physical
constants are dependent on others, so the anthropic principle may rest on
only a very few initial conditions that are really fundamental (Kane et al.
2000). It is further weakened by the fact that different initial conditions
sometimes lead to essentially the same outcomes, as with the initial mass of
stars and their formation of heavy metals (Nakamura et al. 1997), or that
the tuning may not be very fine, as with the resonance window for helium
fusion within the sun (Livio et al. 1989). For all we know, a universe
substantially different from ours may be improbable or even impossible.

[This is really three different arguments. 1) not all constants may be
independent, and initial conditions may play a large role. Could be true,
although they can't demonstrate it to be true, but still makes the
appearance of life all the more unlikely. 2) different initial conditions
could lead to the same outcome. Could be true, but demonstrates the
anthropic principle, in which the universe is tuned for the conditions that
will eventually produce life, and contradicts the first part of the claim
that initial conditions may have dramatically different effects. 3) this
structure of the universe may be the only probable outcome for a universe
based on the fundamental constants. Essentially restating the anthropic
principle, not contradicting it.]


5. If part of the universe were not suitable for life, we would not be here
to think about it. There is nothing to rule out the possibility of multiple
universes, most of which would be unsuitable for life. We happen to find
ourselves in one where life is conveniently possible because we cannot very
well be anywhere else.

[Multiple universes are unproven. If we weren't here, but some other
intelligent being somewhere else in the universe were pondering this
question, what difference would it make? This is dodging the question.]


6. Intelligent design is not a logical conclusion of fine tuning. Fine
tuning says nothing about motives or methods, which is how design is
defined. (The scarcity of life and multi-billion-year delay in it appearing
argue against life being a motive.) Fine-tuning, if it exists, may result
from other causes, as yet unknown, or for no reason at all (Drange 2000).

[Argument from ignorance, and changing the subject. Fine-tuning anthropic
arguments don't claim to answer questions of methods or motives, only
providing a justification for the belief that life was intended.]


7. In fact, the anthropic principle is an argument against an omnipotent
creator. If God can do anything, he could create life in a universe whose
conditions do not allow for it.

[Another philosophical fallacy, like the question "Can God make a rock so
big he can't move it?" Either way you answer, it (apparently) contradicts
the notion of God's omnipotence.]


Jon Tandy
(ASA member)

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Received on Mon Apr 21 10:58:23 2008

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