Cosmology and the mediocrity principle

[otseng]

The mediocrity principle is the philosophical notion that "if an item is drawn at random from one of several sets or categories, it's likelier to come from the most numerous category than from any one of the less numerous categories" (Kukla 2009).[1] The principle has been taken to suggest that there is nothing very unusual about the evolution of the Solar System, the Earth, humans, or any one nation. It is a heuristic in the vein of the Copernican principle, and is sometimes used as a philosophical statement about the place of humanity. The idea is to assume mediocrity, rather than starting with the assumption that a phenomenon is special, privileged or exceptional.[2][3]

http://en.wikipedia.org/wiki/Mediocrity_principle

Current cosmology assumes that the mediocrity principle is true. Our solar system, the earth, and humans are not special. But, is this assumption true? Why or why not?

[help3434]

For one thing if you are asking if we can say whether or not unicorns exist in the universe, the answer is no. We can't say, because we can't exam the entire universe.

The lack of evidence for unicorns on earth is pretty profound precisely because the earth is within our reach to explore thoroughly.

I don't think we can ever explore the entire universe (or even the earth). But, I would agree that if we did explore every single place in the universe (or earth), then we can then definitely say whether something exists or not. But, that is quite a high bar to reach, which I think is an unpractical level.

I don't think we need to reach the point of conclusiveness to make a claim. I believe one can reasonably make a claim based on available evidence, until new evidence is presented to the contrary. In my epistemology, I would simply say that based on the lack of any evidence for unicorns, they do not exist.

I believe this is also how most atheists think. They believe that they will not believe in something if no evidence exists for it. Since they believe that no evidence exists for God, then God does not exist. If they used your line of reasoning, they cannot say if God exists or not since they cannot explore the entire universe, let alone outside the universe.

Your line of reasoning is at least consistent. You make no claims of God or aliens or unicorns since we have not explored everywhere. So, it's a reasonable position to take.

For atheists, I do not find it consistent. Atheists believe God does not exist since they believe no evidence exists. But no evidence also exists for aliens, yet none, as far as I know, would claim that no aliens exist.

What you seem to be failing to understand (or refusing to acknowledge) is that it is simply not possible for us to explore the entire universe for signals from sentient life forms.

Yes, I understand that. And yes, I fully acknowledge that we can only explore a limited part of the entire universe.

Here is really my only point. We think that other intelligent life exists not based on any evidence, but only on the mediocrity principle.

We have a small set of data of the universe. Out of this small set of data, there is no evidence for aliens. There remains a large set of data that could point to the existence of aliens. But, what is the justification that evidence do exist in the unexplored set of data? I maintain it's only because of the assumption of the mediocrity principle. There is no way that we are special, so other life must exist.

In fact, technological aliens might have reasons to want to hide.

I think it's quite presumptuous to guess the motivations of things we don't even know exists.

The claim that God exists and that life might exist somewhere else in the universe besides this one planet are quite different. Do you really think they are equivalent. We have no evidence that Supreme Beings exist, but we do know that life exists. Going from the fact that life exists to thinking that life might also exist somewhere else is not much of a stretch.

[Danmark]

The proper question is not whether 'unicorns exist or not,' but what is the evidence they might have existed. If there is no evidence the unicorns have existed, why should we posit they might have existed? With no evidence at all that 'X' exists or has ever existed, why should X even be the subject of inquiry?

Sure, valid questions. Is there any evidence that aliens have existed? If there is no evidence that aliens exist or have existed, why should aliens be a subject of inquiry?

I agree with that. If there really is no evidence that points to the possible existence of aliens, then why make it the subject of inquiry? However, sometimes the evidence can be subtle. If the orbit of Uranus wobbles a bit or is slightly different than expected it is worth positing an unknown cause, particularly if that unknown, such as a planetoid would explain the observation.

I also would make a distinction between something that deserves inquiry from something we merely wonder about.

[Danmark]

Your presupposition that I even have such arguments is incorrect, and it demonstrates that you weren't been paying attention when I expressed my position on this.
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Wow. Wow. That's ludicrous. Absolutely not. Do you honestly think that putting forth bad arguments makes your position more tenable?

All you've offered is circular arguments and your own personal intuition. Your score is 0.
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I'm perfectly capable of putting forth opposing arguments of equally fallacious caliber to yours, but I'm not going to.

Because it would be stupid.

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[Divine Insight]

The claim that God exists and that life might exist somewhere else in the universe besides this one planet are quite different. Do you really think they are equivalent. We have no evidence that Supreme Beings exist, but we do know that life exists. Going from the fact that life exists to thinking that life might also exist somewhere else is not much of a stretch.

I totally agree. The arguments that Otseng is making are not rational arguments. They are extremely irrational.

We exist as lifeforms in this universe. As do all the other living things on planet Earth. We have also determined by examination that we are made of precisely the same stuff that the rest of the universe is made of, with absolutely no indication whatsoever that anything more than this is required for living beings. Therefore it is extremely rational to believe that other lifeforms similar to life on Earth (i.e. beings made entirely from the constituents of this universe) most likely also exist.

That is a perfectly rational assumption. In fact, it's actually quite irrational to believe that we would be the only living things in the entire universe when we can see that the universe is homogeneously made of the same stuff we are.

On the other hand, we have absolutely no reason to believe in imaginary supernatural beings that are invisible and we have never been able to detect. The only reason we even consider them at all is because mankind has invented these types of beings in religious folklore.

Moreover, there is overwhelming evidence that these ancient folklore of imaginary Gods is indeed nothing more than the superstitious imagination of men. For example, nobody takes Greek religious folklore seriously anymore. They are totally content and satisfied to put in on a self marked "fiction" and treat it as nothing more than superstitious mythologies.

The only folklore that has truly survived in any abundance is the folklore of Hebrew mythology. That folklore itself has fallen into extremely divisive folklore where every version of it makes different claims of a supposedly personified "Father God" who behaves like an extremely immature adolescent human in all cases. According to the folklore this God tries to solve problems using very crude, rude, and violent methods that were clearly the types of methods used by the uncivil society that created this folklore. And more to the point, none of these attempts to solve any problem had even worked, according to the folklore itself.

We have absolutely no rational reason in the world to even remotely think that these ancient rumors of a supposedly omniscient omnipotent God who can't even solve the simplest of problems might actually exist. It's totally irrational.

Yet, arguments are being made that try to compare the hypothesis that other life might exist in the universe with the hypothesis that one of these ancient myths of a totally contradictory God character might exist.

Such arguments are not rational at all.

We have absolutely no rational reason to believe that these ancient man-made folklore of Gods that can't solve problems are anything more very poorly written superstitions.

But we do have very rational reasons to believe that we may not be the only living creatures in this universe. Just look at how diverse life is on earth. If life can be so diverse on earth then why should it not also be diverse enough to exist elsewhere in the universe?

From a purely rational point of view we should believe that it would be exceedingly improbable that we are the only life in the universe. That would be the less likely scenario for sure.

[FarWanderer]

In fact, technological aliens might have reasons to want to hide.

I think it's quite presumptuous to guess the motivations of things we don't even know exists.

Like God?

[FarWanderer]

Do you have any particular reason to believe the initial mass of the universe was "produced" by the universe, or, even assuming that it was, that it was finite?

Where did I say the universe was produced by the universe?

Nowhere. I think you misread, unless you actually equivocate "initial mass of the universe" with "universe".

Although instead of "mass" I should have written "matter/energy".

Whether you meant mass or matter/energy, where did I ever say or imply that the mass/matter/energy of the universe was produced by the universe?

Here. I bolded the part.

But since you seem to be making an argument here, I'll address it. Your implied argument, that "no reason to accept not A" makes for "reason to accept A", is fallacious. It's ignores the possibility of "no reason to accept not A" and "no reason to accept A" as both being true.

Here are some arguments to support finite matter/energy:
- If the universe is finite in age, then it could not have produced infinite matter/energy.
- If the universe has infinite matter/energy, then it would have infinite size.
- Since the universe is finite in age and not infinite in size, then the universe has finite matter/energy.

1) Who says the universe "produces" matter/energy at all? You are aware of the first law of thermodynamics are you not?

I'm not implying that the universe is constantly producing matter/energy. I'm just referring to the moment of initial "creation" of the universe.

If I misinterpreted, you'll have to explain how. Because I don't see it.

My problem with your universe has never been that it's finite; it's that it has an arbitrary border.

Yes, there would be a boundary with a finite universe. Does it intuitively seem absurd? Perhaps. But, I think it naturally follows from a finite universe.

It doesn't even follow. A torus universe is finite and has no border.

I'm referring to a flat, Euclidean, finite universe. A torus universe is not flat and Euclidean.

Can you agree that science can make no claims as to whether any "less than 1 Planck time" even exists?

If 1 Planck time exists, then we don't know if less than 1 Planck time exists?

That's right. By our current scientific understanding, 1 Planck time is the smallest measurable duration in principle. That means that as far as we know, Planck units are genuinely indivisible and time lengths like "0.4 Plancks" or "3.7 Plancks" are impossible.

However, the important question is whether a t=0 exists. And I maintain very strongly that our current scientific understanding does not imply that it does.

Any time a theist says "science cannot explain X therefore there's a supernatural cause" they are assuming that no unknown natural explanation for X exists.

It's only assuming that based on current understanding, no viable naturalistic explanation exists.

Exactly.

It's often a useful presupposition in dealings in everyday life, but it is absolutely inapplicable to understanding what is (or is not) beyond the natural world.

To sum it up, there are two categories of observable phenomenon: there's ones we understand through empirical observation as natural processes, and there's ones we simply do not understand. Whether the latter are natural processes or whether they are otherwise is unknown.

You, on the other hand, have to assume there isn't one in order to make your argument.

Never said that. All I've said is that currently there is no viable naturalistic explanation.

You made this argument:

If it's a purely naturalistic explanation, matter would not even escape a black hole, so I do not think a purely naturalistic explanation is at play.

At face value, you most certainly did not say "currently viable". Now, I'm not interested in playing "gotcha" with you, so I won't have a problem agreeing that "currently viable" is implied by context somehow and I simply didn't get the memo. However that brings up a whole new set of problems.

Allow me to reword your argument for simpler understanding.

First, as your argument reads to me:

If matter escapes a black hole, then there's no natural explanation.
Matter escapes a black hole.
Therefore, there's no natural explanation.

This argument is valid. However, it assumes there's no natural explanation for matter escaping a black hole, including any we have yet to discover.

Next, as you seem to be saying that I should have interpreted your argument:

If matter escapes a black hole, then there's no known natural explanation.
Matter escapes a black hole.
Therefore, there's no natural explanation.

This argument is downright invalid because the conclusion would include unknown natural explanations as well. In other words, the conclusion doesn't follow.

Finally, a third form:

If matter escapes a black hole, then there's no known natural explanation.
Matter escapes a black hole.
Therefore, there's no known natural explanation.

But that conclusion isn't of any use to you.

So, to sum up, your argument either assumes perfect scientific understanding, is invalid, or is trivial. Those are your choices. Personally, I think this argument should have never been made.

If the cosmological principle is true, sure, metric expansion of space is probably the only way to explain things. But, there are some things I find problematic with the metric expansion of space. What is causing it? Is space uniformly expanding at every single point in the entire universe at the exact same rate? If so, what can account for that?

As I understand it, the dark energy model has an answer for all those questions. Although, like any explanation, it raises new questions. I personally find the concept of dark energy quite weird at first glance, but I'm not really in a position to judge.

Dark energy and dark matter are another example of ad hoc explanations to me.

Even if dark energy was the cause of the metric expansion of space, it still does not answer the question if every single point in the entire universe is expanding at the exact same rate.

That's an interesting claim. Might I ask what you understand about the dark energy hypothesis beyond it being a supposed explanation for the expansion of space?

In any case, the more important point is that the answers aren't required. We don't need to know the cause of a phenomenon to know it exists.

If you're referring to the metric expansion of space, I would not classify it as a phenomenon, but an assumption.

That's not it. The point is you can always ask "what can account for that" to any explanation. Just because you don't understand what might account for something doesn't make it unreasonable to believe that it is real.

You are free to argue the merits of the visible universe comprising most of the complete universe.

If there is no metric expansion of space and the universe is approximately 15 billion years old, the radius of the universe cannot be more than 15 billion light years.

And if there is, then the radius can be larger. What's your point?

Yes, if there is metric expansion of space, the universe can be much larger than 15 billion light years in radius.

All I'm saying is that if there is no metric expansion of space, it cannot be larger than 15 billion light years in radius.

Sure, but this claim of yours is not of particular significance to me unless you intend to tie it in with some other argument.

Do our measurements of the most distant galaxies indicate they are no more than 15 billion light years away?

Depends on what you mean by measurements. We cannot really directly measure distances on that scale. Many assumptions have to be made to calculate very far distances.

Need to go, we can talk more about this later.

None of this "if" stuff you are saying about the radius of the universe matters unless you provide a reason that we shouldn't believe the universe is more than 15 billion light years in radius.

I was asking if measurements were your reason.