The Fine Tuning Myth

Fine Tuning and the Argument from Probability

In his 1995 book, The Creator and the Cosmos, physicist Hugh Ross listed thirty-three characteristics a planet must have to support life. He also estimated the probability that such a combination be found in the universe as "much less than one in a million trillion." for human life.

He concluded that only "divine design" could account

However, Ross presented no estimate of the probability for divine design. Perhaps it is even lower! Ross and others who attempt to prove the existence of God on the basis of probabilities make a fundamental logical error. When using probabilities to decide between two or more possibilities, you must have a number for each possibility in order to compare. In this vast universe, highly unlikely events happen every day.

In a 2004 book called The Privileged Planet, astronomer Guillermo Gonzalez and theologian Jay Richards have carried the notion further, asserting that our place in the cosmos is not only special but also designed for discovery. They contend that conditions on Earth, particularly those that make human life possible, are also optimised for scientific investigation and that this constitutes "a signal revealing a universe so skilfully created for life and discovery that it seems to whisper of an extraterrestrial intelligence immeasurably more vast, more ancient, and more magnificent than anything we've been willing to expect or imagine.

Read why these arguments are misleading here  (from page 144)

Jason Waller provides a version of the argument for fine tuning that goes like this...

1) The universe is fine-tuned for the evolution of intelligent life.

2) This fine-tuning is most likely the result of either (i) chance or (ii) Minimal Theism.

3) The likelihood that the fine-tuning is the result of chance is astronomically low (something like 1 in 10 to the 50.)

4) The likelihood of Minimal Theism (while itself pretty low) is not astronomically low(that is, it is much higher than 1 in 10 to the 50.)

5) Therefore, Minimal Theism is probably true.

Some issues with Jason's logic:

The probability that our universe exists as it does is 1.

But if we're trying to figure out what the probability of the universe existing was before it came into existence (which is the only meaningful way to address this question) then it can't be calculated because we have no idea what variables led up to its creation. We cannot (as far as we know) look back to "before" the big bang and look at all the parameters involved, so there's no way to put a value on how likely any of them are, let alone all of them happening as they did. Waller's number "1 in 10 to the 50" is entirely made up.

It is possible that our universe is the only possible universe - that no matter what happened before the big bang, the only way the universe could shake out would be exactly as it has. It's hard to imagine, for example, that pi could be set to any other value because its value comes directly from its abstract definition. Perhaps all the fundamental constants are the same way. They couldn't be set otherwise.

It's equally possible (because we can't put values on these possibilities) that our universe is nearly infinitely unlikely - that every possible parameter we can think of could be set at any possible value and the chances of ours arising over others is statistically zero (far smaller than the 10^-50 figure Waller uses). In fact, if any one parameter could exist on a sliding scale, say, the speed of light could have been set at any value above 0 and below infinity, then the probability of the universe existing with c set as it is is infinitely low (unless the values have to be some multiple of some other constant, aka, quantized, but even then, assuming the quantization value is on the order of the Planck length, it would be much smaller than 10^-50).

And even if we could enumerate all the possible values of the variables involved, we're going to get stuck on the definition of "as it does". Does "as it does" refer only to the values of the fundamental physics constants? Does it also require the exact amount of initial energy? Does it require the same perturbances in the initial fields that set all the matter on the exact same course that it did in our universe? Does it require that I like vanilla ice cream more than chocolate?

Waller's argument seems to define "as it does" to mean "able to give rise to intelligent life" but we have no way of knowing this probability because we have no idea what a universe would look like if the initial conditions had been different. Who can say that life could or couldn't be possible if c were set to some other value?

So, not only are the parameters impossible to evaluate, but the requirement for satisfying the probability isn't well-defined.

Anyone who puts a value on this is making it up.

Victor Stenger's Respose to The Argument from Probability

If we properly compute, according to statistical theory, the probability for the universe existing with the properties it has, the result is unity! The universe exists with one hundred percent probability (unless you are an idealist who believes everything exists only in your own mind). On the other hand, the probability for one of a random set of universes being our particular universe is a different question. And the probability that one of a random set of universes is a universe that supports some form of life is a third question. I submit it is this last question that is the important one and that we have no reason to be sure that this probability is small.

I have made some estimates of the probability that a chance distribution of physical constants can produce a universe with properties sufficient that some form of life would have likely had sufficient time to evolve. In this study, I randomly varied the constants of physics (I assume the same laws of physics as exist in our universe, since I know no other) over a range of ten orders of magnitude around their existing values. For each resulting "toy" universe, I computed various quantities such as the size of atoms and the lifetimes of stars. I found that almost all combinations of physical constants lead to universes, albeit strange ones, that would live long enough for some type of complexity to form (Stenger 1995: chapter 8). This is illustrated in figure 1.

Figure 1. Distribution of stellar lifetimes for 100 random universes in which four basic physics constants (the proton and electron masses and the strengths of the electromagnetic and strong forces) are varied by ten orders of magnitude around their existing values in our universe. Otherwise, the laws of physics are unchanged. Note that in well over half the universes, stars live at least a billion years. From Stenger 1995.

Every shuffle of a deck of cards leads to a 52-card sequence that has low a priori probability, but has unit probability once the cards are all on the table. Similarly, the "fine-tuning" of the constants of physics, said to be so unlikely, could very well have been random; we just happen to be in the universe that turned up in that particular deal of the cards.

Note that my thesis does not require more than one universe to exist, although some cosmological theories propose this. Even if ours is the only universe, and that universe happened by chance, we have no basis to conclude that a universe without some form of life was so unlikely as to have required a miracle.