Anthropic Principle IS a probability argument

Glenn R. Morton (
Sat, 09 Jan 1999 13:11:09 -0800

While my example may have been flawed (and I bow to your correction), I
want to press a bit on this below:
I wrote:
>>Then do you discount the anthropic principle? Barrow and Tipler do not
>>calculate probabilities, but the entire anthropic argument is that it is in
>>some emotional sense, difficult to belief that all the constants could be
>>correct for life to exist. If this isn't an implicit probability
>>calculation I don't know what is.
At 01:10 PM 1/9/99 EST, David Bowman wrote:
>I don't know about whether or not it is an "implicit probability
>calculation" but I, for one, *do* profoundly get the feeling (from
>natural theology) that the universe is somehow made *for us*, or at
>least that we are meant to be here. I don't know if natural theology
>can go much (or any) further than this though.

Of course it must be a probability argument. If it were not one why does
the following statement (by you) lead ultimately to the feelings described

>There are very many ways for life (as we know it) to be impossible by
>making a slight adjustment of just a relatively few fundamental
>constants (e.g. number of dimensions of space & time, numbers of
>generations of elementary particles, coupling constants and mixing angles
>for the fundamental interactions, the masses of the elementary particles,
>etc.) whose values determine all the rest of the phenomenology of the
>physical world.

The usage of the word 'slight adjustment' implies that it doesn't take much
change. And when you compare this to the possibility that it could have
taken a huge change in the above parameters to kill off life, the concept
of an implicit probability argument becomes clear. If it took a huge
change in all the physical constants to prevent life, then we would say,
'it is easy to create a universe compatible with life'. Any value would, in
those circumstances lead to life. The constants could take on a wide range
of values and the taking of any of those values would be compatible with
life. But since only a slight change prevents life, the universe appears
precariously balanced.
So, in this sense I will defend the approach I used to calculate
probabilites if not the example.

While, I can't find the reference on where I got my inverse square example
(I will post it if I ever find it again) I one of your suggestions with
documentation to back up what I am saying. It is that the universe with
life MUST have 3 spatial dimensions.

(Barrow and Tipler pp 267-275;"Only three-dimensional worlds appear to
possess the 'nice' properties necessary for the transmission of
high-fidelity signals because of the simultaneous realization of sharp and
distortionless propagation." p 269 Living systems require this for
communication via nerves and sound)

(Brrow and Tipler, "ONly for N=3 is gravity the distinguised interaction"
p. 269)

(If I am reading Barrow and Tipler right, only in a 3 spatial dimensional
universe can the gravitational constant be constant p. 275)

Thus we 'feel' that it is improbable to have this value of 3 by chance.
If any dimensionality would allow life to exist, then the probability is
high that any dimensionality the universe chose would be compatible with
life and dimensionality would not be a restriction on living beings.

In other words if the universe can accomodate any dimensionality it would
NOT be specially adjusted to our existence. It would be JUST the
dimensionality chosen by historical accident. But what we have is a
universe in which only one value allows life. It is like flipping a coin
and having it not be heads nor be tails but land on the coin's edge. This
is theoretically possible, but highly improbable. But mathematically we
contemplate euclidian and non-euclidian spaces with from 0 to 3.5 billion
dimensions (3.5 billion is the number of dimensions in the phase space of
the human DNA). So there is no mathematical restriction on the
dimensionality of any space we wish to contemplate. But only with a 3D
universe can we exist. At the very least the odds against randomly
choosing a 3d universe compatible with life from those mathematically
contemplated (at least occasionally) is 1/3.5 billionths. And if any of
those dimensionalities allowed for life, then the odds would be 1. And if
the dimensionality probability were 1, then once again, we would say it is
easy to create a universe with life. To me this is a probability argument.

Thus I contend that the anthropic principle IS a probability argument and
if used one is implicitly calculating probabilites to get the "feeling (from
natural theology) that the universe is somehow made *for us*". If one can
do this, then your's and Howard's objections to probability calculations
would be inconsistent. So, if you feel that the universe is designed for
us, then it must be possible to calculate probabilities. If you can't
calculate probabilities, then the anthropic principle fails entirely and
this universe is NOT designed for us--or at least there is no evidence of
that design.

Adam, Apes and Anthropology
Foundation, Fall and Flood
& lots of creation/evolution information