Is ESP More Probable Than Advanced Alien Life?

[Fudbucker]

No, it doesn't. I would claim, for example, that the discovery of the chemical precursors for life-forms on extra-terrestrial bodies makes the existence of alien life-forms more likely.

Yes, you could use that as evidence, the problem still remains, that even if the the discovery of exoplanets and non-terrestrial amino acids confirms the hypothesis that alien life exists (and I agree it does confirm it), it's not clear how much confirmation those discoveries give to the hypothesis that alien life exists.

I addressed this in another post. If H is alien life and E is the evidence you're talking about brought up, Pr (H/E) is still unknown because of we don't know what the probability of abiogenesis occurring on a Earth-like planet is AND how many planets in the universe there are that meet the necessary conditions for life.

For example, suppose I said that a "grue" is in your house. Without defining what "grue" is, you don't know what the probability is that a "grue" is in your house. It's impossible to determine. BUT, let's say I told you that a "grue" is NOT a unicorn NOR is it the Hope Diamond. By ruling out two things that are almost certainly NOT in your house, I've confirmed the claim that "a "grue" is in your house", however, even though the claim received some confirmation, you still don't have enough information to assign a probability to the claim.

To make a long story short, just because evidence confirms a claim, it doesn't mean that the probability of the claim can be determined. If the probability of the claim still is undefined, even after confirmation from some piece of evidence, we still have nothing to work with.

---------------

There's also one other thing to point out. Yes, it's true that the evidence you talked about (and also the discovery of exoplanets) made it more reasonable to believe that alien life exists. However, an argument could be made that the degree of belief to which we assign scientific claims was dealt a blow by the discovery that the universe is expanding at an accelerating rate AND that vast majority of the universe is comprised of mysterious energy and stuff (and remains mysterious, decades later).

In 1980, which isn't all that long ago, if you had posited that there are huge amounts of mysterious stuff and energy permeating the universe AND that the universe is expanding at an ever faster rate, I think you would have been regarded as a kook, on par with someone claiming ESP exists. If that's true (that our faith in scientific claims was knocked down a notch or two recently), then that makes "wooish" claims, like ESP exists, more probable.

That's not an argument I'm currently making, but I think one could have some success making an argument along those lines.

 

[John Jones]

Jt is right. Science is inductive. The probability of all inductive claims is between zero and 1. The probability that the Earth goes around the sun is not 1. It has a lot of 9's in it, but it's not 1.

For any observation, there are always competing theories to explain it, and only the logically impossible/incoherent explanations can be a priori ruled out.

I can't believe you're still carrying-on about this. You lost the debate a long time ago.

Give it a rest.

 

[Fudbucker]

Yes I understand this for any *specific* observation.

But the laws of physics, taken as a whole, are a system. Outside of quantum level theories, they are 100% true -- if you change *any* of them, the rest fall apart. That's why it is called "physics" and not "an independent collection of models that have nothing to do with each other."

That's why observations of non-perfect confidence can lead to a model that we have perfect confidence in. There are literally zero alternative models that simultaneously predict the high number of observations.

Also remember that all scientists work on an assumption that the future will resemble the past. This, of course, is Hume's famous "riddle of induction" (which was updated by Goodman). While we can assume it's highly probable the future will resemble the past, it's not necessarily true (100% certain) that future observations will be consistent with past observations. There is a non-zero chance that future observations will be totally different from past observations.

 

[Fudbucker]

I can't believe you're still carrying-on about this. You lost the debate a long time ago.

Give it a rest.

There is no debate- scientific claims never have a probability of 1. Anyone who thinks they do is wrong.

I wouldn't bother debating this fact any more than I would bother debating a Young Earth Creationist. Anyone who disputes it is either an idiot or extremely ignorant.

 

[jaydeehess]

There is no debate- scientific claims never have a probability of 1. Anyone who thinks they do is wrong.

I wouldn't bother debating this fact any more than I would bother debating a Young Earth Creationist. Anyone who disputes it is either an idiot or extremely ignorant.

If that's not a straw man you can point to several posters arguing that the probability of advanced life forms in this universe, in addition to humans, is equal to 1.

 

[Red Baron Farms]

There is no debate- scientific claims never have a probability of 1. Anyone who thinks they do is wrong.

There is a scientific probability of 1 that there is civilised life in the universe. Also, currently, there is a scientific probability of 0 for ESP. Give me a good rational scientific hypothesis of how ESP could exist, or an example, and then we could assign a non-zero prior probability to ESP. Until that point we have absolutely no way to assign a non-zero probability to ESP.

1 is always greater than 0

The bayesian probabilities applied are: 1 times some unknown factor for alien life, and 0 times some unknown factor for ESP.

1x is also always greater than 0.

QED

PS ETA I have been saying that in different ways since post # 84.

 

[jt512]

uppose I said that a "grue" is in your house. Without defining what "grue" is, you don't know what the probability is that a "grue" is in your house.

Actually, I would have no problem assigning a probability to the hypothesis that a "grue" is in my house without knowing what a "grue" is. I would have two competing hypotheses: H1, a grue is in my house, and H0, no grue is in my house. Since I don't even know what a "grue" is, I can have no evidence that would cause me to favor either H1 or H0 over the other. Moreover, I have no reason to think it more likely that you were telling me the truth or not. Consequently, I have two competing propositions, exactly one of which has to be true, and absolutely no reason to believe one more than the other. Therefore, my probability for each proposition must be 0.5.

--------------------------​

Although I have agreed with you on some fundamental points about induction, I have to say I totally disagree with the claim in your OP that ESP and alien life are equally probable. First, you make lengthy arguments that neither the probability of alien life nor the probability of ESP can be determined. Those arguments are wrong, because they treat probabilities of hypotheses as objective. But such probabilities are subjective, and in the worst case scenario, where we have absolutely no information whatsoever about whether a hypothesis is true or not, as I explained above, our probabilities for those hypotheses should be 0.5.

But the above is really beside the point, because we don't have to determine the probabilities of either alien life or ESP to determine which one is higher. As another side note, it is very odd that you argue that we have to calculate these probabilities to determine which one is greater but not to determine that they are equal. But back to the main point, life on earth is an example of life. So we know life has spontaneously evolved once. We also know that the universe is immense and almost surely comprises an enormous number of natural "laboratories" where conditions could also arise for life. So we have no concrete reason to believe that there is no alien life, and some reason to believe that it is likely. But, even if I completely discount this evidence, a lower bound on the probability of alien life must be 0.5, because in the worst case, I have no evidence one way or the other about the proposition, and thus no reason to favor the proposition over its complement, or vice versa. At worst, it's a "grue" problem.

In contrast, we have the very successful Standard Model of particle physics, according to which no particles or forces exist that would allow for ESP. The probability that the Standard Model is wrong is thus an upper bound on the probability of ESP. The theoretical physicist Sean Carroll has suggested that that probability is less than 1-in-1-million.

So, the probability of ESP, which in principle violates our best understanding of physics, is less than the probability of alien life, which in principle does not. That is really all we need to know to determine which has the greater probability. I didn't need any probabilities at all to do that. That said, based on the probability bounds that I did quote, I would have to say that alien life is at least six orders of magnitude more probable than ESP.

 

[jt512]

Also, currently, there is a scientific probability of 0 for ESP. Give me a good rational scientific hypothesis of how ESP could exist, or an example, and then we could assign a non-zero prior probability to ESP. Until that point we have absolutely no way to assign a non-zero probability to ESP.

PS ETA I have been saying that in different ways since post # 84.

Yes, you have been, even after I explained to you why you were wrong.

 

[Red Baron Farms]

Yes, you have been, even after I explained to you why you were wrong.

I read your explanation. I even understand it. I simply don't agree with it. Specifically I don't agree with this statement:

So, if L(x) is the value of the likelihood function, given some new data x, and your prior probability is 0, that data cannot change your probability, since 0 × L(x) = 0. In other words, if your prior probability is 0, no amount of evidence can ever change your mind; your opinion is immune to evidence

There is a flaw in your logic. You presuppose that there was a prior. There isn't for ESP. That's what has fudbucker stuck. He is, like you, trying to assume a non zero prior. In order to even use Bayesian probabilities, you must have a prior rational non zero hypothesis, or lacking that, evidence. The fallacy is the same as the old Russell's teapot analogy.

Without a rational hypothesis, the assigned value is zero. But since it is assigned and not calculated, new evidence or new hypotheses allow a new prior to be assigned instead. With new evidence or a new hypothesis you wouldn't multiply against the old factor of zero. You would substitute the new non zero factor INSTEAD of zero.

 

[Fudbucker]

Actually, I would have no problem assigning a probability to the hypothesis that a "grue" is in my house without knowing what a "grue" is. I would have two competing hypotheses: H1, a grue is in my house, and H0, no grue is in my house. Since I don't even know what a "grue" is, I can have no evidence that would cause me to favor either H1 or H0 over the other. Moreover, I have no reason to think it more likely that you were telling me the truth or not. Consequently, I have two competing propositions, exactly one of which has to be true, and absolutely no reason to believe one more than the other. Therefore, my probability for each proposition must be 0.5.

--------------------------​

Although I have agreed with you on some fundamental points about induction, I have to say I totally disagree with the claim in your OP that ESP and alien life are equally probable. First, you make lengthy arguments that neither the probability of alien life nor the probability of ESP can be determined. Those arguments are wrong, because they treat probabilities of hypotheses as objective. But such probabilities are subjective, and in the worst case scenario, where we have absolutely no information whatsoever about whether a hypothesis is true or not, as I explained above, our probabilities for those hypotheses should be 0.5.

But the above is really beside the point, because we don't have to determine the probabilities of either alien life or ESP to determine which one is higher. As another side note, it is very odd that you argue that we have to calculate these probabilities to determine which one is greater but not to determine that they are equal. But back to the main point, life on earth is an example of life. So we know life has spontaneously evolved once. We also know that the universe is immense and almost surely comprises an enormous number of natural "laboratories" where conditions could also arise for life. So we have no concrete reason to believe that there is no alien life, and some reason to believe that it is likely. But, even if I completely discount this evidence, a lower bound on the probability of alien life must be 0.5, because in the worst case, I have no evidence one way or the other about the proposition, and thus no reason to favor the proposition over its complement, or vice versa. At worst, it's a "grue" problem.

In contrast, we have the very successful Standard Model of particle physics, according to which no particles or forces exist that would allow for ESP. The probability that the Standard Model is wrong is thus an upper bound on the probability of ESP. The theoretical physicist Sean Carroll has suggested that that probability is less than 1-in-1-million.

So, the probability of ESP, which in principle violates our best understanding of physics, is less than the probability of alien life, which in principle does not. That is really all we need to know to determine which has the greater probability. I didn't need any probabilities at all to do that. That said, based on the probability bounds that I did quote, I would have to say that alien life is at least six orders of magnitude more probable than ESP.

Would you give me even odds on a bet of your life savings that a "grue" is in your house?

 

[jt512]

I read your explanation. I even understand it. I simply don't agree with it. Specifically I don't agree with this statement:

Yes, but in Bayesian inference, data update the prior multiplicatively (through the likelihood function). So, if L(x) is the value of the likelihood function, given some new data x, and your prior probability is 0, that data cannot change your probability, since 0 × L(x) = 0. In other words, if your prior probability is 0, no amount of evidence can ever change your mind; your opinion is immune to evidence.

There is a flaw in your logic. You presuppose that there was a prior.

I did not presume a prior; quite to the contrary, you supplied it. You said that the probability of ESP was 0. If that's your current assessment of the probability, then that is the prior probability which we would enter into Bayes' Theorem to update using any new data we obtain.

In order to even use Bayesian probabilities, you must have a prior rational non zero hypothesis, or lacking that, evidence.

What you have to have is a prior probability for the hypothesis in question. Here, the hypothesis is that ESP exists. You supplied the prior probability: 0. (What does a "prior rational non zero hypothesis" even mean? You assume to be confusing the hypothesis with its probability.)

Without a rational hypothesis, the assigned value is zero. But since it is assigned and not calculated, new evidence or new hypotheses allow a new prior to be assigned instead.

Uh, no. You just made that up. There is absolutely nothing in Bayesian inference that permits you to just throw out your prior probability (whether it is 0 or not, and whether it calculated or assigned) and just start over with a new one.

With new evidence or a new hypothesis you wouldn't multiply against the old factor of zero. You would substitute the new non zero factor INSTEAD of zero.

I don't know what kind of inference you think you're describing, but it sure as hell isn't Bayesian.

 

[Red Baron Farms]

I did not presume a prior ... I don't know what kind of inference you think you're describing ...

Exactly. You must do that

The theorem itself can be stated simply. Beginning with a provisional hypothesis about the world (there are, of course, no other kinds), we assign to it an initial probability called the prior probability or simply the prior. After actively collecting or happening upon some potentially relevant evidence, we use Bayes’s theorem to recalculate the probability of the hypothesis in light of the new evidence. This revised probability is called the posterior probability or simply the posterior. Specifically Bayes’s theorem states (trumpets sound here) that the posterior probability of a hypothesis is equal to the product of (a) the prior probability of the hypothesis and (b) the conditional probability of the evidence given the hypothesis, divided by (c) the probability of the new evidence.[1]

It actually is necessary (required) you do that.

The more we study it, the more we appreciate how nicely Bayes' theorem corresponds to, and improves on, our common sense. In the first place, it is clear that the prior probability is necessarily present in all inference; to ask, "What do you know about A after seeing the data B?" cannot have any definite answer because it is not a well posed question if we fail to take into account, "What did you know about A before seeing B?"[2]

Now it appears that, for all these years, those who have seemed immune to all Bayesian explanation have just misunderstood our purpose. All this time, we had thought it clear from our subject matter context that we are trying to estimate the value that the parameter had when the data were taken. Put more generally, we are trying to draw inferences about what actually did happen in the experiment; not about the things that might have happened but did not.[2]

Not only must you assign a prior, it must be rational and consistent with the known laws of physics.

in our system it is a platitude that all probabilities referring to the real world are, of necessity, conditional on our state of knowledge about the world; they cannot be merely postulated arbitrarily at the beginning of a problem.[2]

There is no set for ESP. We have zero examples and zero rational hypotheses. Zero 0 nada none null and void. The only rational prior, lacking both evidence and also lacking hypotheses, is zero. In other words H(0)=0. (The null hypothesis)


Oh and BTW Thanks very much for taking me to task on this issue. Without your insistence, I wouldn't have Googled Bayesian calculus and refreshed my knowledge of how to properly use it. It has been about 30 years after all!

 

[jt512]

I did not presume a prior

Exactly. You must do that

No one could be so stupid as to believe that they could get away with intentionally misrepresenting someone by quoting only half a sentence in the very preceding post; so, I have to conclude that you actually did not read all the way to the end of the sentence. What I actually wrote, was:

I did not presume a prior; quite to the contrary, you supplied it.

In other words (little ones), I was explaining to him what the consequences (oops, big word) were of using his prior probability of 0.

[The prior] must be rational and consistent with the known laws of physics.

Now you, too, are just making stuff up. A prior probability is subjective, personal. For better or worse, some people have irrational beliefs, and hence irrational priors. For example, some people believe exaggerated claims about the effect on human health of how livestock is raised. Other people believe in ESP. Such beliefs might be irrational, but we, or they, can assign them a probability which we can update as new evidence arrives. A key, foundational fact of Bayesian inference is that no matter how irrational our hypothesis is, it will always be overcome by sufficient evidence. This is a feature of Bayesian inference that skeptics, in particular, should appreciate: Bayesian inference can shoot down irrational beliefs about subjects like homeopathy, psi, etc. Your prior probability of homeopathy might be .99, but if enough evidence shows that homeopathy is ineffective, then Bayesian inference guarantees that your probability will (asymptotically) approach 0. No matter how irrational your initial beliefs are, with sufficient evidence they must become rational if you update them in accordance with Bayesian principles.

There is no set for ESP.

You've made that statement more than once. What does it even mean?

Oh and BTW Thanks very much for taking me to task on this issue. Without your insistence, I wouldn't have Googled Bayesian calculus and refreshed my knowledge of how to properly use it. It has been about 30 years after all!

I don't know what to say to that except that you've managed to misunderstand what you've read and somehow used it to incorrectly reinforce your prior misunderstanding. That's not something I particularly want to be thanked for.

 

[jt512]

Would you give me even odds on a bet of your life savings that a "grue" is in your house?

No, of course not. The risk doesn't match the potential reward. Taking utility into account, the cost of losing my life savings is greater than the gain by doubling it; so it's not an even bet. But if we set out the terms of the bet carefully enough I would give you even odds on, say, a $100 bet.

 

[Red Baron Farms]

I don't know what to say to that except that you've managed to misunderstand what you've read and somehow used it to incorrectly reinforce your prior misunderstanding. That's not something I particularly want to be thanked for.

Oh but it is so Bayesian. I started with a prior and all the evidence so far increases the likelihood of that prior being correct. Your assumption that it is incorrect is actually not Bayesian. You start with a prior and examine the evidence. Ultimately whether you like the result or not, Bayesian inference guarantees that your probability will (asymptotically) approach the truth. Since you are still making unreferenced claims, and I searched for actual evidence and found it everywhere I looked......... What conclusion should I draw?

 

[jt512]

Oh but it is so Bayesian. I started with a prior and all the evidence so far increases the likelihood of that prior being correct. Your assumption that it is incorrect is actually not Bayesian. You start with a prior and examine the evidence. Ultimately whether you like the result or not, Bayesian inference guarantees that your probability will (asymptotically) approach the truth. Since you are still making unreferenced claims, and I searched for actual evidence and found it everywhere I looked......... What conclusion should I draw?

You have indeed brought to light an under-appreciated aspect of Bayesian inference: in order to validly apply evidence that you have read, you actually have to have understood it.

 

[Puppycow]

I'll take a crack at this. Sorry if I'm repeating something that's already been said, but I think I know the answer and have a valid reason for the answer.

First, what is the probability of advanced alien life existing (by advanced I mean the same tech level as we are (or higher))?

Since we know for certain of one existing example of this (ourselves) we know that it is possible in principle. Since we know this is possible and has happened at least once in the history of the universe, we can deduce that there is a probability greater than zero that it could happen somewhere else. We do not know that ESP is possible even in principle, and I think we have good reasons to doubt that it is. I know of no single verifiable example of this phenomenon occurring. Therefore the probability might be zero. Since it goes against what our best theories of science seem to indicate, that further sheds doubt.

Is ESP possible? Yes. The default position is that a thing is possible until it's been proven impossible. A tea cup floating around Jupiter is possible (though very very unlikely).

A tea cup floating around Jupiter is possible in principle, but again, I'm not sure that ESP is. I disagree about the "default position". Can pigs fly? Has anyone proven that they can't? My default position is that it isn't possible that pigs can fly until someone proves that they can. I see no value in trying to prove something in a rigorous formal way that is so obviously true.

Just to be sure we're talking about the same thing, I looked up the definition of ESP:
http://en.wikipedia.org/wiki/Extrasensory_perception

Extrasensory perception or ESP, also called sixth sense, includes reception of information not gained through the recognized physical senses but sensed with the mind. The term was adopted by Duke University psychologist J. B. Rhine to denote psychic abilities such as telepathy, clairaudience, and clairvoyance, and their trans-temporal operation as precognition or retrocognition. ESP is also sometimes referred to as a sixth sense. The term implies acquisition of information by means external to the basic limiting assumptions of science, such as that organisms can only receive information from the past to the present.

Parapsychology is the study of paranormal psychic phenomena, including ESP. Parapsychologists generally regard such tests as the ganzfeld experiment as providing compelling evidence for the existence of ESP. The scientific community rejects ESP due to the absence of an evidence base, the lack of a theory which would explain ESP, the lack of experimental techniques which can provide reliably positive results,[1][2][3][4][5] and considers ESP a pseudoscience.[6][7]

In conclusion then, the probability of advanced alien life existing is much greater than that of ESP.

 

[Craig B]

No. Only necessary truths are "100%" true. There's nothing necessary about the laws of physics (either taken separately OR as a whole). They are contingently true and are based on observations that fallible humans have made.

Fortunately, we're being asked in this thread to consider whether one proposition is more probable than another, so this philosophical issue of 100% truth doesn't arise.

However, I repeat my warning against the idea, that because neither of two propositions can be said to be certainly true, they must be equiprobable. That is a fallacy.

 

[Puppycow]

However, I repeat my warning against the idea, that because neither of two propositions can be said to be certainly true, they must be equiprobable. That is a fallacy.

Well said.

It is more probable that there is a mouse in my back yard right now than that there is a dragon. I don't know for certain whether either is true, although I have seen a mouse in my backyard in the past.

 

[Craig B]

Well said.

It is more probable that there is a mouse in my back yard right now than that there is a dragon. I don't know for certain whether either is true, although I have seen a mouse in my backyard in the past.

What does Bayes' Theorem have to say about this?