Bayes' Theorem

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Bayes' Theorem

Postby Metacrock on Sun Nov 18, 2012 12:25 pm

Bayes' Theorem, got into ruckuss on board with a guy claiming that ECREE is Bayes' Theorem. I think it's derived but he say "it's a fact. it is the theorem exactly>" He also says it's a fact, the theorem is a fact, it can't be disputed, therefore, it's a fact that you can't have arguemnts for god becuase inadequate due to thrum.They can't give extraodinary proof.

He rediscussed t read my essay.

http://religiousapriori.blogspot.com/2010/01/extraordinary-claims-argument-ecree.html
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Re: Bayes' Theorem

Postby fleetmouse on Sun Nov 18, 2012 2:00 pm

It so happens that I was reading Carm today (please shoot me) and saw the thread in question.

Here is what Sylar had to say:

'ECREE' is merely an English statement of Bayes's Theorem. A claim with a low prior probability needs a higher likelihood than a claim with a high prior in order to have the same posterior. You are not only wrong, but incompetently wrong. That's it; that's ALL 'ECREE' is saying. This is a mathematical fact. You can even see a very simple proof here.

And, contrary to what Meta claims, it is use all the fracking time. For example, let's look at drug tests. Last year, an estimated 0.5% of the general US population used cocaine. Let's assume that we have a 99% accurate test for cocaine. People like Meta will try to tell you that this means that anyone who tests positive on a random drug test has a 99% chance of having actually done cocaine. The reality, however, is that if we plug the numbers into Bayes's Theorem, we see that there's nearly a 66% chance of it being a false positive.

'ECREE' is why we never do just one test for cancer. Extraordinary claims do in fact require extraordinary evidence; this is mathematical fact.

I'm not allowed to use the image tags, but here is a good cartoon about 'ECREE': http://xkcd.com/1132/


Interesting thread, actually. http://forums.carm.org/vbb/showthread.p ... -idea-quot

Metacrock, if you're arguing against Bayes' theorem you're a bit silly. Really. There are few, if any, more useful and universally applicable mathematical concepts (well, maybe addition and subtraction :mrgreen: ). A good overview is here: http://betterexplained.com/articles/an- ... s-theorem/

This doesn't mean you can't have arguments about or discuss God, or that God is impossible. It just means that ECREE. And you're missing the EE (extraordinary evidence) part that would make some of your arguments more, uh, compelling.
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Re: Bayes' Theorem

Postby Metacrock on Sun Nov 18, 2012 5:14 pm

do actually read English? you are French Canadian and you don't read English? what did I say. read what i said again.

I really expect people who calm to be my friend to actually read what I say.
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Re: Bayes' Theorem

Postby Metacrock on Sun Nov 18, 2012 5:16 pm

they do not test more than once for cancer becuase they think it requires extraordinary proof to prove cancer. That is total absolute rubbish. I did not dispute that ECREE is derived from Bayse. but there's no way on God's Green earth that cancer is considered extraordinary.

I's about probably so obviously it doesn't apply to arguments that don't use probability that's just obvious.

where did I say that Baye's theorem doesn't work? quote where I said it.
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Re: Bayes' Theorem

Postby fleetmouse on Sun Nov 18, 2012 5:42 pm

What exactly is your problem with Bayes' theorem and ECREE then?

Bayes' theorem applies anywhere probability applies - which is to say, everywhere, including tests for cancer and cocaine use.[/quote]

other than atheists trying to misuse it I don't have one. I never said I did. they see Bayes the read "ECREE" as though there is no difference there is a difference.

ECREE is a plain-language paraphrasing of Bayes' theorem as it applies to contentious claims such as miracles: if something is extraordinarily unlikely to have happened, then you should quite rightly think that it's extraordinarily unlikely that it did happen, unless you have extraordinarily good evidence to the contrary.


I did it again. I wrote in your post. hit edit rather than quote. I'm sorry man.
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Re: Bayes' Theorem

Postby Metacrock on Mon Nov 19, 2012 11:55 am

If anything in your post is missing it's because I accidentally wrote in it due to hitting edit rather than quote. I've done so many times I'm really sorry.

fleetmouse wrote:What exactly is your problem with Bayes' theorem and ECREE then?

Bayes' theorem applies anywhere probability applies - which is to say, everywhere, including tests for cancer and cocaine use.


other than atheists trying to misuse it I don't have one. I never said I did. they see Bayes the read "ECREE" as though there is no difference there is a difference.

ECREE is a plain-language paraphrasing of Bayes' theorem as it applies to contentious claims such as miracles: if something is extraordinarily unlikely to have happened, then you should quite rightly think that it's extraordinarily unlikely that it did happen, unless you have extraordinarily good evidence to the contrary.


no it's not! It's derivative of but it's not a "plain language version of it." Bayes has noting at all to do with arguemnts about God. you can't use it to argue that arguments for God are not extraordinary enough. The concepts are totally different. I kept pushing them to say that ECREE is a translation of Bayes to the same event that "en arche en o logos" is a translation of "in the beginning was the word" they started wavering and going "well it's not exactly the same but it's the general idea." these are just ideolgoical overstatements designed to win an argument. they are careful considerations.

Or to put it another way: skepticism of an extremely unlikely and poorly substantiated event is warranted.


now you've gone over the line to another whole concept. that's not about "extraordinary" it's about "extremely unlovely." so get's to decide what's unlikely? I thin it's extremely unlikely that there would not be a God.



(of course cancer is far more likely than, say, resurrection, but the talk of cancer is just to frame Bayes' theorem in an understandable everyday example)


that doesn't prove that they check cancer twice for that reason. i never seen them quote a statistician or logician. The only people they ever quote on that stuff are atheists and atheist pitch men like Sagan. Distorting the reasons for things doesn't make good examples.

For one thing when you look up the meaning of Bayes it doesn't anything about extraordinary , unless it's from a source that's arguing for atheism.


Web definitions

In probability theory and applications, Bayes' theorem shows the relation between a conditional probability and its reverse form. For example, the probability of a hypothesis given some observed pieces of evidence and the probability of that evidence given the hypothesis. ...

en.wikipedia.org/wiki/Bayes_Theorem


Stanford Encyclopedia of philosophy
http://plato.stanford.edu/entries/bayes-theorem/

Bayes' Theorem is a simple mathematical formula used for calculating conditional probabilities. It figures prominently in subjectivist or Bayesian approaches to epistemology, statistics, and inductive logic. Subjectivists, who maintain that rational belief is governed by the laws of probability, lean heavily on conditional probabilities in their theories of evidence and their models of empirical learning.


by the way that one seems to imply that there epistemologists and logicians who don't even agree with the "proved fact" of Bayse's therefrom.

a website just called "Bayse's theorem"

http://www.trinity.edu/cbrown/bayesweb/
Bayes' Theorem is a theorem of probability theory originally stated by the Reverend Thomas Bayes. It can be seen as a way of understanding how the probability that a theory is true is affected by a new piece of evidence. It has been used in a wide variety of contexts, ranging from marine biology to the development of "Bayesian" spam blockers for email systems. In the philosophy of science, it has been used to try to clarify the relationship between theory and evidence. Many insights in the philosophy of science involving confirmation, falsification, the relation between science and pseudosience, and other topics can be made more precise, and sometimes extended or corrected, by using Bayes' Theorem. These pages will introduce the theorem and its use in the philosophy of science.



nothing in those three about "extraordinary."
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Re: Bayes' Theorem

Postby fleetmouse on Mon Nov 19, 2012 8:59 pm

Stop, please, this is getting out of control. I don't want to argue everything anyone's ever said about cancer and Bayes and vocabulary and the divisions between what's extraordinary and what's simply unlikely. Also I see you are on Carm talking about punching people in the nose over this issue, so let's please calm the fuck down and take stock of the situation.

As I see it there are two important issues here:

1) the relationship between Bayes' theorem and ECREE

2) whether Bayes or ECREE apply to discussions of theism at all

Do you agree that these points are the crux of the matter?
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Re: Bayes' Theorem

Postby Metacrock on Mon Nov 19, 2012 9:07 pm

fleetmouse wrote:Stop, please, this is getting out of control. I don't want to argue everything anyone's ever said about cancer and Bayes and vocabulary and the divisions between what's extraordinary and what's simply unlikely. Also I see you are on Carm talking about punching people in the nose over this issue, so let's please calm the fuck down and take stock of the situation.

As I see it there are two important issues here:

1) the relationship between Bayes' theorem and ECREE

2) whether Bayes or ECREE apply to discussions of theism at all

Do you agree that these points are the crux of the matter?


yes. we an limit discussion to that.


However, I'm hung up on the injustice of the way they do me. they are still acting like I said Bayes is stupid and wrong. what do I have sign a pledge that I support Bayes or something. It's obviously not what I think. why are they so anal retentive?
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Re: Bayes' Theorem

Postby QuantumTroll on Tue Nov 20, 2012 5:08 am

I'm going to start by taking Metacrock's side here, for once. As a working numerical scientist, I feel like I have a bit of weight to throw around on this subject, too ;)

I think Metacrock is right in that the claim "ECREE" with regards to the existence of God has little or nothing to do with Bayes' Theorem. The reason for this is actually clear when you look at the examples in this thread, cocaine use and cancer. If you give a random US citizen a cocaine test, the low incidence of cocaine use means that you'll get a lot of false positives. Cocaine use is an extraordinary claim, and you need a very accurate test (or several tests) in order to convincingly show cocaine use. If you go to a crackhouse, you'll probably be able to tell pretty reliably who is high at the moment without any drug test. Similarly, any particular cancer diagnosis is a rare and extraordinary claim, and the tests have limited power. But if one test is positive, you're in a cancer crackhouse, and more testing will be much more reliable. Bottom line: You need to know the prior odds of an outcome to know the reliability of a test.

We don't know the prior odds of the existence of God. We cannot apply Bayes' Theorem to this question, because we don't have any data about the existence of God, period. I think this is the heart of Metacrock's point, and in this he is correct.

A caveat: I think the existence of God is an extraordinary claim, and my intuition says that such claims require extra convincing evidence. I agree with ECREE with regards to the existence of God, but will not use Bayes' Theorem as support for this opinion.

Finally, there's the whole miracles issue, too. Here, we do know the prior odds of spontaneous recovery from various illnesses, or we can at least calculate a reliable estimate. Therefore, when someone prays and is healed, we can apply Bayes' Theorem and we do have a mathematical basis for ECREE in this context. Every argument for miracles (at Lourdes or elsewhere) that I've seen has failed to address this fundamental problem. Can Metacrock dig up a counterexample?
Last edited by QuantumTroll on Tue Nov 20, 2012 7:39 am, edited 1 time in total.
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Re: Bayes' Theorem

Postby Metacrock on Tue Nov 20, 2012 7:33 am

I appreciate your comments a great deal man. That's super and actually talking my side, wow, mark n the wall! :D

I agree with what you say. The only thing I would add is that many atheists, not you of cousre, or Fleet, but those who are less well immersed in scinece make it seem as though belief in god is extraordinary in the sense of being cray, way out, they leave the impression that "extraordinary" means "freaky and silly and way out."

Obviously it doesn't mean that. It means different the average. soemthing like that. yet the average in terms of belief for humans is to believe in some form of deity or God.
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