Is it a fallacy, and if so which, to believe we are special because our existence on Earth seems improbable?

Question

People often use the argument that there must be a God, for example, because Earth and the laws of physics are perfectly situated for humans to exist the way we do. However, if Earth or even the universe as a whole were not situated so that life could evolve, then we wouldn't even exist to be able to question our own existence. So there's nothing interesting or special about our existence at all--this is just the only "scenario" in which humans exist, and another scenario easily could have occurred in which we do not exist, but of course humans would never be around to observe such a thing.

Is this some type of fallacy and is there a name for it?

Answer 1

I believe you're thinking of the anthropic principle. There are actually two variations:

The strong anthropic principle says that the universe was made the way it is so that humans could exist.

The weak anthropic principle says that the universe must be such that humans could exist, since here we are.

The strong anthropic principle is considered fallacious. The weak version, however, is perfectly valid. It's used e.g. in cosmology to dismiss hypotheses that would exclude the possibility of human life ever developing.

Answer 2

The underlying problem (and fallacy) with this argument is sometimes referred to as the 'Texas Sharpshooter' fallacy.

One is standing from a position of a known situation and asking what are the odds that everything turned out exactly as it has, which is always going to be incredibly improbable. If one shuffles a pack of cards, then looks at the order and declares 'the odds of this particular order coming up are astronomical, so it must be a miracle', this is not sound reasoning. There are indeed near-infinite ways the universe could have turned out, and this happens to be the permutation we got, but whatever happens there would have been some outcome.

Essentially, it's declaring the target after the event has occurred.

Answer 3

Your description is somewhat vague so that the reasoning might mix several things.

1) Base rate fallacy. "The laws of physics are perfectly situated for humans to exist the way we do" is either tautological or it is unclear how probabilities are being assigned to "collections" of laws of physics that allow "humans to exist the way we do." The sample space and the base probability measure on it are not particularly intelligible. "It seems rather unlikely" that the universe should allow humans to exist is a "gut feeling" with no prior basis for estimation. The no miracles argument for scientific realism suffers from a similar affliction. "It would be a miracle if the science were as useful without also being true" does not follow from any intelligible base probability assignment, we'd need something like an ensemble of "sciences" describing "reality," and access to what reality "truly is" over and above those "sciences."

2) Intelligent design fallacy. The "perfectly situated for humans" claim assumes that even granting that they are "unlikely," conditions allowing human existence could not have evolved over time from something much more generic, the way Earth evolved from conditions rather inhospitable to life. Similar to arguing that "irreducible complexity" prevents the gradual evolution of intricate structures like the eye, which therefore must be "pre-designed." In this case, it's assumed that conditions favorable to human existence have to be "pre-designed" in the laws of physics.

3) Anthropic reasoning. We observe what we see because otherwise, we wouldn't be here to observe it. This is fine as long as it is only meant as a constraint on theories describing our observations. However, typically anthropic reasoners offer it as something more, an explanation of what we observe. For it to work as such one needs a bloated ontology of the multiverse, where a whole ensemble of universes with different physical laws is instantiated. Then it would naturally be "likely" (when conditioned on our existence) for us to find certain (unconditionally) "unlikely" features in it. This also needs a meaningful assignment of probabilities to the universes to avoid problems with the base rate fallacy. While not necessarily fallacious this sort of reasoning is highly speculative and metaphysically loaded, making it controversial among physicists.

Answer 4

It's not a fallacy.

The first argument you mentioned is known as the teleological argument, which goes: Look at all the minutiae of cosmology, geology, and biology, and marvel. If anyone of them were slightly different we could not have existed. Therefore there must be some fine-tuner, because it is too improbable that everything would have lined up so perfectly.

Indeed, if you were to draw from the distribution of all possible universes, and find that the one you drew harbored life, that would be a huge coincidence (probably, I can only speculate about that distribution). But the teleological argument fails to consider that we have a VERY strong prior, in the statistical sense: that our existence and ability to ask the question is contingent on those parameters being fine tuned in the first place.

The anthropic principle acknowledges this observer/selection bias. We should not at all be surprised to find that our universe is "fine-tuned", unless we have some reason to believe that it is exceptional beyond some minimal configuration to support intelligent observation (I'd point to the fact that is is 99.9999% vacuum with a smattering of rocks, and that we are organic slime on the surface of one of those... does it honestly look that fine-tuned?)

Answer 5

What you describe is called the fine-tuning argument - that out of the full possibility space of the laws of physics, only a very small fraction permits intelligent life, so some creator must have fine-tuned physics. Whether it is a valid claim is an ongoing debate in philosophy of religion, so it would be unfair to call it a fallacy per se, but one can certainly argue that it is based on a fallacy. In your argument, that fallacy would be the observational selection effect. The Stanford Encyclopedia of Philosophy (always a great resource) gives a formal version of such an argument (see section 4.1.1.2 here for the full version): the usual formulation of the fine-tuning argument P(universe is suitable for life|universe was designed) >> P(universe is suitable for life|universe is random), so upon observing that the universe is suitable for life, we conclude that it must be designed. But that ignores the observation bias: what we actually can calculate are P(universe is suitable for life|universe was designed & observers exist) and (universe is suitable for life|universe is random & observers exist), and clearly both of those values are 1 (the universe must be suitable for life if observers exist) so we don't actually learn anything from observing that the universe is suitable for life.

Answer 6

I don't know if this answer exactly matches your question. But one variant on this sort of thing started out as creationism, then became "Intelligent Design." As I understand it, the idea is that we are special not because we are improbable, but because we are impossible - not the sort of thing that could be the result of natural processes.

But note this is not a fallacy; it is not even an absurd argument. The uncomfortable fact is that creationists are correct when they say e.g. that evolution is "just a theory." Of course, it is, just like all science! Science is not itself something that can be studied by science; it rests on various articles of scientific faith (like "the world is orderly"), just as religions rest on their articles of faith. The mistake the creationists make is to go from "we're naturalistically impossible" to "therefore there must be a God, namely the one I believe in." Even worse, they try to enlist science in support of obviously non-scientific propositions. But their core idea - that science is not the only arbiter of truth, it's impeccable.

Whether we are naturally impossible, or even just improbable, is not a scientific question. Even if we were to discover a population of humans on a distant planet we would not be able to definitively "prove" that both they and we are the products of nature. You can't put probabilities on supernatural events. Something like that is why some of our best scientists are devoutly religious.

Answer 7

Era answered with the anthropic principles. Let me make it more clear how that relates to your question:

• The strong anthropic principle: Earth/the universe has been made the way it is so that it could and would produce human beings.
• The weak version: Humans are the way they are because the universe is like it is.

The strong variant almost necessarily needs a God figure (i.e., an intention for the creation of the universe); it also violates Occams Razor, falsifiability and is as egocentrical as believing that the stars and Sun rotate around Earth. Hence a fallacy. N.B., it nearly enforces humans as observers, and proponents will likely also argue that there can only be humans, because the argument is made to let humans seem to be special.

The weak one is just a more or less bemusing statement that is obviously true for every possible universe and every possible observer. It triggers no further philosophical or physical questions. It allows for any kind of (un)imaginable observer to evolve. It does not make humans special in any way and allows for multiple different types of observer (a.k.a. aliens).

Note that it makes not that much difference if you replace "human" by "intelligent being" or "observer"; the most important point about it is whether there was an intention to create observers that went into the design of the universe.

Answer 8

I'd like to give a different kind of answer than the ones above, in the hope of shedding light on your question from a different angle: rather than talk about the subject matter of teleological arguments and anthropic principles, I'll just say a bit about how arguments work.

"Fallacy" is a term we use to describe how an argument fails to be logically valid - that is, how the premises fail to entail the conclusion. For instance, I might say, "A implies B; B; therefore A." We call this "the fallacy of affirming the consequent" in order to communicate where that argument went wrong. If that second premise had been "A" rather than "B," we would have had a valid argument with the conclusion "B."

So "fallacy" is only a good term to use insofar as the thing you're talking about is purported to be a deductive argument. But the argument you gave in your question does not have a form anything like a deductively valid argument, so (even if it is indeed an invalid argument in some way) it will be hard to say where exactly a fallacy lies, or what it is - hence the multiplicity of answers here.

Or, to speak more generally, since it's hard to say exactly what the argument that you're asking about is, it's also hard to say what, if anything, is wrong with it. If, as your tags suggest, you're interested in the logic of this question as well as the subject matter, you'll have to be a bit more specific.

EDIT: I don't say this, by the way, just to be pedantic. Some versions of the teleological argument are logically valid, and others are not. I'm of the opinion that you'll have the most fruitful and enlightening discussion only after you've figured out what sort of argument you're evaluating.

Answer 9

We're probably not very special - and regarding the physical conditions required for our existence, these apparently existed on this planet long before we did.

If conditions had been radically different on earth, some other intelligent life form may have evolved - and may have asked the same kind of question.

The semantics of logic are not ever going to solve this conundrum.

Answer 10

First some corrections, because your premise is wrong: Earth and the laws of physics are perfectly situated for humans to exist.

No, it isn't. Earth was until a very, very recent time completely uninhabitable for humans. Almost half the time Earth had no oxygen at all. 90% of Earth time there was nothing to eat at all. Only during the Perm period (300 million years) and after the mesozoikum (< 70 million years) carbon dioxide levels were low enough to allow breathing for us. But during the Perm giant insects existed, pointing to high oxygen levels (35%) which are detrimental for us. So "Earth" allowed only a very small timeframe for us.

It is also not plausible that the laws of physics (or natural sciences in general) are perfectly situated. Protozoa do not need to die. Humans have trouble with the upright stance. If it is perfectly situated why did smallpox exist and why could we eradicate it without noticing that something very important is missing now ?

So, if anything, the question should be if life itself is improbable. As observers it is very hard to carefully judge the evidence because we do not know what is reliable or simply an assumption.

• Let's look at the argument of the fine-tuned parameters. If we change some fundamental constants and interactions only a tiny bit, life becomes impossible. The problem is: Are the parameters independent of each other and could they have other values ? If someone can develop a theory that automatically restricts many or all of those parameters the very, very small probability can become noticable.

• Another option: If we assume that life cannot exist in space and lifeforms are bound on their planet, we could actually use multiclipation of probabilities to arrive at very low probalities because each lifeform must form independently. If we for the sake of argument assume that panspermia is possible (lifeforms can be propelled in space, survive there and seed planets), then the probability that life forms on a hospitable planet is rather high.

My stance is that the final probability depends on so many unknown knowledge that it is currently more an intangible riddle and while arguments for the improbability of life are existing and may even be right, they are currently not very strong.