Is the anthropic principle a "cop-out"?

Question

Forgive me in advance for the provocative title. It's likely I only have a pop-science understanding of the AP and there is something important I'm missing. That's why I'm asking the question!

My understanding of the anthropic principle is that it's a response to the apparent fine-tuning of the laws of physics. Given that some physical constants such as the strength of charge of an electron could seemingly be different to what they are, but if they had been only slightly different, organic life would have been impossible, it seems that our existence depends on a very very improbable state of affairs estimated at odds of thousands to one.

Sometimes it's said that this very improbable initial state demands an explanation: why did things turn out just as they did, in such a fashion as to allow stars, planets and organic life to exist, when the universe could just as easily have been nothing more than a big cloud of hydrogen?

The Anthropic Principle, as I understand it, is a response to this: The universe had to have had that improbable initial state, all those seemingly finely-tuned physical constants, because if it had not then we would not be here to ask the question why!

It seems to me that this is is a sort of non-answer. The curious child, or interested amateur, or physics professor, asks why the universe is so complex when it could have been very simple or non existent. Several answers are possible:

• It was intentionally designed that way, whether by a bearded figure sitting on a cloud, a cosmic watchmaker or super-intelligent alien beings programming a simulation
• There is some unknown constraint that meant the values of the strong and weak nuclear forces, etc, had to be as they are and not something else
• There are many universes, so all possible values of physical parameters are instantiated, including the small number which allow for complex chemistry and organic life

The AP seems to address none of these possibilities and actively avoids them. It's a kind of non-answer: since we're already here, the universe had to allow for that, so why wonder about it, why not ask some other question instead? And it gives this non-answer in a way that seems to elevate human organic life from something contingent into something fundamental to the physical parameters of the universe.

Am I misunderstanding the issue, or is the AP not really scientific explanation?

Answer 1

Cop out? No not exactly. It's just that the fine tuning argument doesn't require much of a reply as things stand. It just means that no matter the probability of the events that led up to us existing, those events had to occur.

The main problem with the fine tuning argument is that we don't know exactly why things like electrons get their exact charge so it's hard to understand how they can be different, so calculating the probability's is difficult to begin with, so we're dealing with the calculation of probability's of things we don't fully understand.

We would also need to know the probability of the "designer" to compare. So, we're comparing the probability of some natural event we understand poorly to the probability of a "designer" we don't understand at all.

Also, very low probability events happen all the time, and I can sit here and calculate the probably of me having exactly my genetic makeup considering only the pares of humans and the amount of spermatozoa involved and come to the conclusion that I am in fact sitting here is some absurdly low number and thus impossible without divine intervention, or I can realize that there needed to be such an outcome for me to be sitting here typing this reply.

So, we should be a little suspect of statements like: x has a very low absolute probability of happening therefore God, which is the form of the fine tuning argument.

Answer 2

I prefer to think about this in the same way as the "gambling oracle" scam or whatever it might be called.

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Basically: I will tell x·2ⁿ people that I will predict the result of n+1 sport events. At each time I will send out "home team won" to half the remaining people, and "guest team won" to half of them. After the game I won't send anything more to the ones that got the wrong result.

At the end x people will believe that I correctly guessed all events, and then I want them to pay me $1000 for giving them the result of the next game, which I will also guess.

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The fact that we exist to ask the question means that we "correctly guessed the games" up until now.

Whether or not the universe had 2ⁿ chances or guessed right from the start doesn't make a lot of difference.

Answer 3

In his book The Biotic Message: Evolution Versus Message Theory (pp. 61-66, c1993), Walter James ReMine lists three formulations of the anthropic principle, and explains issues with each:

1. The tautological anthropic principle: Stated as, "The universe has survivable (and observable) properties because we survive (and observe)." To quote ReMine a little later, "Does our survival cause the universe to have survivable properties? Yes, in a trivial linguistic sense, it 'causes' it to be true by definition." But tautologies and definitions are not explanatory by themselves; and this doesn't explain why the universe is survivable to being with.
2. The metaphysical anthropic principle: The idea of the multiverse. ReMine says this is "the only [formulation listed] having any explanatory power." ReMine says that because these "other universes" are not observable, they "smack of non-science." It is conjecture, without any observable scientific evidence.
3. The 'lame' anthropic principle: ReMine says that this formulation does not even attempt to explain the issue. He gives the following quote by Barrow and Tipler, 1988 The Anthropic Cosmological Principle, as an illustration if taken "precisely as it stands" (italics by Barrow and Tipler): "The observed values of all physical and cosmological quantities are not equally probable but they take on values restricted by the requirement that there exist sites where carbon-based life can evolve and by the requirement that the Universe be old enough for it to have already done so." ReMine compares this answer by saying, if you ask "Why is the sky blue?", their response would be akin to, "The observed color of the sky is restricted by the requirement that it be blue." ReMine goes on, "Their formulation simply does not explain the problem."

ReMine closes the section by stating how it's possible to shift back and forth between formulations to avoid criticism on any one particular way of stating it:

Ambiguity serves the purpose of allowing theorists to shift effortlessly away from any single line of criticism. If you argue it is tautological, they can shift to either a metaphysical or lame formulation. If you argue it is lame, they can shift to either a tautological or metaphysical formulation. This ability to shift back and forth is key to the illusions about the anthropic principle.

Answer 4

Douglas Adams' puddle analogy does a good job of explaining it.

This is rather as if you imagine a puddle waking up one morning and thinking, 'This is an interesting world I find myself in - an interesting hole I find myself in - fits me rather neatly, doesn't it? In fact it fits me staggeringly well, must have been made to have me in it!'

The physical constants aren't fine tuned for us: they came first. We're fine-tuned for them. If the constants had been different, we wouldn't exist, certainly. Something else would exist instead, and that thing would then be able to say that the physical constants of its universe appear to be perfectly fine-tuned to it, and if they'd been even slightly different (such as, for example, they way they are in our universe), it wouldn't be able to exist.

Now, that explains why it doesn't matter how unlikely it is that we specifically exist, but there does remain the question of how likely it is that a random set of physical constants would permit some form of intelligence that could ask that question. And we really have no idea how know how likely that is (we don't even know how likely intelligence is in this universe). We also don't know if reality only gets one shot at generating a set of physical constants that can do that or if it gets lots of attempts. Depending on the answers to those questions, it could be either exceedingly unlikely that intelligence would arise anywhere or almost certain. We simply don't know yet.

Answer 5

The argument that the AP responds to considers a set of hypothetical universes with different universal constants. To do so, it relies on two important implicit assumptions:

1. "Possible" universes follow, in principle, the same laws as the observable universe, just with different values for certain "parameters", e.g. the charge of an electron.

2. The probability distribution of these parameters can be calculated or at least estimated.

In reality, we have no evidence of any of these assumptions being true or more likely than any other. There is no reason to assume that concepts like "electron" and "charge" make any sense in a random hypothetical universe except for the fact that they do in ours. And even if we assume that they do, the methods we use to guess these probabilities are based on our understanding of our universe.

The AP is, in SE terms, a frame challenge. It points out that the question has implicit assumptions, and that these assumptions are based on how our universe works. In a very different universe, the question would be very different.

Of course "why isn't the universe different?" is a valid question to ask, but going further and assigning probabilities to different configurations requires you to make these "biased" assumptions.

In essence, it's not that "the universe's psrameters are tuned for intelligent life to exist" but rather, "this question is tuned by the universe's parameters (and would not exist in this form in a different hypothetical universe)."

Answer 6

It's the Atheist's equivalent to "Creating Hell"

I recall once reading something written by Augustine, on the question of what God was doing before the creation of the Universe:

I do not answer, as some do, that he was creating Hell for those who ask such questions. Because...

And the rest of the paragraph amounted to, more or less, that that was avoiding the question, and that since time was a property of the universe, there could not have been a "before".

It seems to me that the Anthropic Principle has similar characteristics to "He was creating Hell". Not the implication that the questioner should be ashamed or fearful, but the other characteristics, of giving a non-answer, a rhetorical dodge.

It seems that existential-type questions might not be answerable, and certainly can't be answered at this point with anything beyond speculation, but speculation that proposes a hypothesis is legitimate and allows for follow up of some kind. If this seems an unprofitable use of time, "I don't know" or "Nobody knows yet" are also legitimate answers.

A response which discourages further questions, feels to me like an illegitimate answer.

Answer 7

I'm a physicist, not a philosopher, so I'll just offer some thoughts about how I see this issue perceived in the physics community.

The anthropic principle is intentionally very vague about metaphysical details in order to get the broadest possible acceptance base. (In this, it is a lot like the Copenhagen interpretation of quantum mechanics, but I won't digress on that point.) Obviously, humans will only be around to ask questions about their own existence in a universe that makes their existence possible. On the other hand, this restricts you to the question "What is the 'probability' that the universe is the way it is, given that it contains humans?" rather than the broader question "Why is the universe the way it is?"

Now, my feeling is that a majority of working physicists believe the following from the question:

There are many universes, so all possible values of physical parameters are instantiated, including the small number which allow for complex chemistry and organic life.

This is particularly true for string theorists, who have been the biggest advocates of the anthropic principle as an answer to the string theory landscape problem. However, there is a substantial minority of theistic physicists who might see fine-tuning as evidence of intelligent design.

Note that there are also a lot of physicists who believe in your second option (that there is some principle that constrains the laws of physics to be as they are), but I think that this partially begs the question and partially is unrelated to the anthropic principle. It begs the question because you can always ask, "Why that particular principle rather than another?" And it's unrelated because the premise is not really related to the existence of humans at all.

Finally, I should say that from my own personal perspective, I think that most discussions of the anthropic principle are very parochial on two points:

1. We tend to imagine that life can only consist of the type of organic matter we see in our universe.
2. We only consider the effects on physical formations (atoms, molecules, solar systems, galaxies) that exist in our universe but do not consider physical formations that could exist in universes with other parameters but do not exist in our universe.

The requirements for the evolution of life are very simple: self-replication, mutation, and natural selection. I think that these ingredients can probably be found in a wide variety of physical systems. I have no doubt that if you take the Standard Model of our physics and twiddle with parameters, there will be many parameter combinations that result in very "boring" universes. But I also expect that there are many choices of physical parameters that result in life, but just not life in the same way that it exists on Earth. (It also seems perfectly plausible to me that there are life forms in our universe that do not resemble life on Earth, but that's equally speculative.)

Answer 8

From an ideal Bayesian perspective, the Anthropic Principle might potentially be used to increase the prior probability of a hypothesis about the universe. In brief, it might be possible to use the assumption that the universe must contain intelligent life, to more concisely describe the universe. (And more concise explanations are more likely, assuming they match all the observations.)

It's a bit subtle, and there's a strong possibility that the Anthropic Principle is not helpful at all.

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A brief explanation of ideal Bayesian inference:

Ideally, a Bayesian agent begins with a prior probability distribution across all possible explanations of the whole universe. These explanations consist of computer programs in a minimal language (e.g. specifications of Turing machines). Each program generates a complete sequence of all observations that will ever be seen. Unless two programs generate the exact same sequence of observations, they are mutually exclusive.

The prior probability of a computer program is proportional to exp(-L) where L is the length in bits of the program. This is the Minimum Description Length prior, because it strongly rewards the shortest programs.

As observations arrive, the agent crosses out every computer program that fails to generate the exact sequence of observations seen so far. The shortest programs that have not been crossed out are the most likely explanations for the observations.

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So how does this relate to the Anthropic Principle?

Well, it's conceivable that we might use the Anthropic Principle to write a computer program that describes our observations, which happens to be shorter than computer programs that don't rely on the Anthropic Principle. The program without the Anthropic Principle might go something like this:

Generate a large set of possible universes according to simple rules
N = 124039495098734598767110238... // note: this number keeps going for a while (not shown)
return a sequence of observations based on universe number N from the set

N is long because it encodes (among other things) the exact values for all the universal constants. N occupies most of the space of the program.

Now compare this to a program using the Anthropic Principle to select only those universes that have intelligent life:

Generate a large set of possible universes according to simple rules
N = 4235 // relatively small N, saving space
i = 0
Loop over each universe
  if the universe contains intelligent life: // imagine we have some concise algorithm to check if this is true
    i++
    if i == N:
      return a sequence of observations based on this particular universe

The second program's value of N is much smaller than the first program's value of N, because the "test for intelligent life" filters out almost all of the initially generated universes (if we assume that almost all of the initially generated universes do not have intelligent life). This reduction in the size of N saves some space in the program.

This is counterbalanced by the complexity of the algorithm used to "test for intelligent life." The second program only "wins" if the amount of bits used in the algorithm to "test for intelligent life" is smaller than the reduction in the size of N.

These are some big "ifs." For example, if there's an algorithm to test for intelligent life that requires, say, only 1000 bits of code, and if intelligent life is only present in fewer than 1 in 2^1000 of the generated universes, then the second program based on the Anthropic Principle wins. Are those kinds of numbers plausible?

Answer 9

It depends.

What do you mean by a cop-out? What is the Anthropic Principle trying to resolve? A short answer could be: knowing how it is that the universe is so perfect to make life exists. Trying to understand the universe in a scientific way, with numbers and logic seems a good approach. However, the question turns out to be why is the universe so perfect to make life exists?

Why is it that important that the universe makes life exists? Because of observation? Because the value we give to life?

In one way it does not appear to be a cop-out, as it seems to be a trial to understand accurately with mathematics. However, maybe it is a cop-out because it is trying to understand how and not why.

Answer 10

The Anthropic Principle points out that this is a case of metaphorically speaking about the probability of similar or even identical universes, not our universe in sensu strictu.

The Anthropic Principle is not a poor argument. It rather points out the poor understanding of probability most people show.

Once a singular event (as opposed to probabilistic quantum states) occurred, there is no such thing as a probability. These events did occur no matter their original probability.

Probability is, in a way, the antithesis of causality, so asking why or how some improbable event occurred is a meaningless statement, even compared to other, theoretically more probable (ante facto) events. It is word salad emerging from a poor understanding of what one is talking about. Probabilities mean exactly that we cannot predict or explain why one event occurs and others do not. The maximum we can do is making out or measuring possible states and guessing or measuring their relative frequency of occurrence in repeated processes. That does not mean we can predict any given single event (hence the Gambler's Fallacy).

Accordingly, stating that it just makes no sense to ask how in the world this improbable state of the universe occurred is completely valid since, as a matter of fact, it obviously did occur. Any talk about the probability of our universe is necessarily metaphorical.

Answer 11

You ask:

Is the anthropic principle a cop-out?

No, if you take it to be nothing more than durable metaphysical speculation in the philosophy of physics that occurs because of the natural tendency to think of the universe in possible world semantics. Here are some facts about it.

1. It's a rational approach in the philosophy of physics, and cannot be tested because a universe by definition subsumes conceptually anything that interacts with it in a general sense.
2. It's natural to speculate about the origins of the universe if one embraces the Principle of Sufficient Reason. If there are properties of the universe as any other entity is wont to have, then clearly those properties need some sort of explanation.
3. Mathematical theories of physics are highly rational enterprises, and since they are frequently done divorced largely from empirical evidence, they are sometimes targets of criticism in the same way string theory (PhilSE) and dark matter are.

Therefore, if you mean as a term of abuse "cop-out" indicates that it, like the multiverse and modal realism is metaphysical and not scientific explanation (SEP), then yes, it is a cop-out. As Philip Klöcking has pointed out in his answer:

Accordingly, stating that it just makes no sense to ask how in the world this improbable state of the universe occurred is completely valid since, as a matter of fact, it obviously did occur. Any talk about the probability of our universe is necessarily metaphorical.

That is, from an empirical standpoint, there have been exactly 1 universe we can confirm by experience and experiment, and any non-subjective interpretation of probability (SEP) applied results in a non-sensical analysis. The existence of other universes is at best an instrument of reason, and at worst a dogmatic article of faith.

Answer 12

👉 Yes. It is a cop-out.

And without the hypothesis of multiple universes, the observation that if life hadn’t come into existence we wouldn’t be here has no significance. One doesn’t show that something doesn’t require explanation by pointing out that it is a condition of one’s existence. If I ask for an explanation of the fact that the air pressure in the transcontinental jet is close to that at sea level, it is no answer to point out that if it weren’t, I’d be dead.

— Thomas Nagel: Mind and Cosmos

To use the anthropic principle under the assumption of a single universe was one of the shenanigans introduced by Richard Dawkins. He popularized a mélange of badly distorted or misunderstood arguments taken from more serious atheist literature.

Such arguments bedazzle and stump people; the tactic works if one presents them confidently and with an aura of intellectual superiority (see the sophist brothers in Plato's Euthydemus).

Much of the “New Atheists” literature was not only unreflective and shallow but also simply full of fallacies. It's dead now, but was once very well received, which is still shocking.

Answer 13

The anthropic principal seems like a weak argument against "random physics shouldn't have produced life" because there's a much better one. "Physics constants could have different values" is merely a thought experiment (more on that later). But, if we grant that, the anthropic principle is a perfectly good counter-argument.

To review, the original argument is: the physics of a new universe are random, and allow only a tiny chance life could form. So statistically, there must have been some external force selecting ours for life. The anthropic principle throws in a wrench by showing how statistics needs no external selection if there were a billion lifeless Big Bangs before us. Basically, it says "OK, but you still have to prove this is the only universe"(*). Since we're already talking about different ways universes can work, that seems like a reasonable ask.

But the good argument is that "different values for physics constants" has no basis. It probably comes from the 2017 book "A Fortunate Universe: Life in a Finely Tuned Cosmos" by for-real scientists Geraint Lewis and Luke Barnes. I haven't read it, but "finely tuned" is clearly a literary device and nothing more. You need a hook to sell a science book and taking the reader on a roller-coaster of how stars beat the odds to form the elements needed to make planets -- that's a good hook. The last chapter (I think) even talks about alternate universes. But they're just imagining that the weak nuclear force could have different values, to make it exciting.

For real, we've only seen the way physics works in this one universe. We have no evidence past that. It's possible the start of the universe rolls dice for each value, but we don't know. The current direction of physics -- I think? -- makes it seem more likely there are 3 super-basic thingies, determining everything else, with 2 states each (giving 8 universe types total). But we don't know. That the physics numbers are always what we see now is the most normal thing, science-wise. It's all pure speculation.

Back to "why use the anthropic principle?". The random physics argument is in a long line of science-themed proofs of god. I once read a 1975 book by Duane Gish claiming that recently discovered fossils of crazy creatures proved evolution didn't happen. In the 1980's it was popular to say the 2nd law of thermodynamics disproved evolution. When The Big Bang was popularized there were claims it proved Genisis. Today we've got Young Earth Creationists hard at work using mostly-real geology to show the earth could be only eight thousand years old. These arguments are meant to be persuasive rather than rigorous, so people arguing against them like to attack them on all levels. If some kid thinks different physics universes feels "truthy", they can at least hear an argument against the next step, using the cool-sounding anthropic principle.

(*) Or we could show that other universes also support life at rates way too high than the odds predict, once again suggesting an external force. But that seems too much in the weeds, especially since science fiction suggests we'd see "nearby" habitable universes first, making our statistical test unreliable.