Sunday, April 13, 2014

David Hume and Lawrence Shapiro get it wrong on miracles

I really don't like Hume-- really don't like him. Hume was a closet-atheist-sophist, a triad of my least favorite things. The damage he has done to modern clear logical thought is incalculable.

Philosopher Lawrence Shapiro from the University of Wisconsin, Madison (where else?) picks up Hume's mantle, and repeats Hume's idiot argument about justification for belief in miracles.

Shapiro believes that we never have justification to believe in miracles. From Shapiro's essay, with my rebuttal:

[W]e can all agree that miracles such as Jesus rising from the dead either did, or did not, occur. My claim is that, to date, evidence for such an event — and any other event that is regarded as a miracle — is too weak to justify anyone’s belief in it as fact. 
I claim no great originality for my argument. I’m borrowing from the great Scottish philosopher David Hume, particularly Section 10 of his magnificent Enquiry Concerning Human Understanding (1748). If there is any novelty in my presentation, it owes to the marriage of Hume’s ideas with a famous theorem in probability theory proposed by the Reverend Thomas Bayes in ‘An Essay towards solving a Problem in the Doctrine of Chances’ (1763). The technical details, fortunately, can be put to the side for our purposes.
The argument begins with an assumption that is very favourable to those who believe in miracles. Let's say that the witnesses of miracles are very reliable — far more reliable than ordinary witnesses. This is not to say that miracle witnesses are infallible. If they were, then of course we could trust their reports and there would be nothing more to discuss. But witnesses, we know, are never perfect. Things aren’t always as they seem, our eyes on occasion mislead us, and sometimes we see what we want to see. When a courtroom drama hinges on a witness who turns out to have identified the wrong person, no one doubts that such misidentifications are possible. 
Even so, for the sake of argument, let’s suppose that witnesses to miracles almost never err. Of all the reports they make in the course of their lifetime — hundreds, thousands, even 100,000 — they make only one mistake. Should we believe someone who claims to have witnessed a miracle if his or her testimony has a chance of only one in 100,000 of being wrong? 
Now I want to consider a slightly different question, albeit one that will have lessons for how we should answer the question above. Suppose you visit your doctor for a routine check-up. After testing a sample of blood, the doctor grimaces. ‘I have bad news for you,’ he says. Bad indeed. You’ve tested positive for a very lethal form of cancer. Your chance of surviving the next three years is practically zero. A treatment exists, but it carries significant costs (blindness, incontinence, all your hair falling out). Furthermore, your doctor says, the test is very good. In every 1,000 tests, it gives only one false positive – that is, a diagnosis of cancer to someone who doesn’t have the disease. Also, 0.001 per cent of the time it goes wrong the other way, giving a negative result to someone who really does have the disease. Do you opt for the treatment? 
The correct answer is this: before deciding, you need a piece of information that the doctor did not provide. Without information about the base rate of the disease – its frequency in the population at large – any facts about the reliability of test are completely useless. 
To demonstrate this, let’s first suppose that the cancer is not terribly uncommon. Perhaps it affects 0.001 per cent of the population. This means that, for every 1,000 people in the population, one person will have the disease. We also know that the test goes wrong 0.001 per cent of the time. That is, it errs one time in 1,000, and it errs in two ways. If we select 1,000 people at random from a larger population, one person in this group who is actually healthy is likely to test positive for cancer. However, the chances are that this group also contains one sick person, because the base rate of the disease, as we’ve said, is one in 1,000. Yet, because the test fails to detect cancer only one time in 1,000, chances are very good (999/1,000) that the test will correctly identify the sick person in the group. This means that, having tested 1,000 people, our test ends up ‘diagnosing’ two of them with cancer, when in fact only one of them has it. Given the base rate of the disease and the sensitivity of the test, if you’ve tested positive, the chance that you are actually sick is only 50 per cent. 
An obvious but interesting conclusion follows. If we hold the accuracy of the test constant but decrease the base rate of the disease, the trustworthiness of the test result diminishes accordingly. For instance, let’s now suppose that the base rate of the disease is one in 10,000. That extra zero means that, having tested positive, the odds of genuine sickness slip down to 10 to one. With its one-in-1,000 error rate, the test will identify 10 people as having the disease when they do not, and one as having the disease when he or she does. Making the disease rarer still, so that it affects only one in, say, 1 million people, puts the chances of illness at a vanishing 1,000 to one. So, this test of ours turns out to be no good at all when the disease for which it tests is rare.
This reasoning would be appropriate to a medical screening test used for people at random, in which there is no reason to believe that a particular disease is present.

But the appropriate analogy to a Christian belief in the Resurrection is not a medical screening test. That is, that Christians are not beginning with no reason to believe the Resurrection is true. Belief in the Resurrection, for a Christian, is belief in one aspect of a truth that has many facets and extensive confirmation in myriad aspects of their lives.

The analogy to a Christian belief in miracles is that of a patient who goes to a doctor with fever, unexplained weight loss, spontaneous bleeding, anemia, swelling of lymph nodes, and recurrent infections, who has a blood test that shows acute myelogenous leukemia. While AML is rare (incidence 1/20,000/year) and the diagnostic test probably has an error rate of at least 1/1000, the likelihood that the patient has AML is very high, and the patient would be a fool to believe that because of the incidence of the disease and of the error rate of the test that the positive result is almost certainly an error.

If Shapiro were a doctor, and told his patient not to worry about the test result, he would loose his medical license. Too bad he doesn't have a philosophy license he could lose.

The reason that the diagnosis is almost certainly true is that the prior probability of a serious hematological disorder is quite high given the patient's presenting symptoms (fever, weight loss, spontaneous bleeding, anemia, etc). The test and the frequency of the disease must be considered in context.

The same is true of a Christian's belief in the Resurrection. The Christian belief that Jesus rose from the dead is not an isolated belief, as it would be if the Christian believed that Joe Smith rose from the dead 2000 years ago, based on a few old books. The belief in the Resurrection is but one (essential) part of a Christian worldview, predicated on life experiences, study of the Bible and of theology, prayer, etc.

I believe that Christ rose from the dead because I have met Him (in prayer, in bible study, in my daily life, in my work...). Whatever confidence an atheist like Shapiro may place in my experiences, I am most certainly not accepting Christ's Resurrection as screening test: "gee- I wonder how likely the Resurrection of one guy in 100 billion is, based on a few 2000 year-old books?"

Lawrence digs a deeper hole:

The practical lesson is this: knowledge of the rate at which a test errs tells you nothing by itself about whether the test results should be trusted. You need also to consider whether the thing for which you are being tested occurs frequently or seldom. If the disease is rare and you test positive, you should look for another explanation for your result than actual illness. Given a test that errs one time in a 1,000 and a disease that is present in only one person in a million, there is a better explanation. Evidently, the test is sensitive to factors other than disease. Something in your blood, perhaps, triggered the positive outcome. This possibility is far more likely than that the disease was responsible for the positive result. Indeed, it’s 1,000 times more likely.
You also must consider the prior probability that the miracle is true. The prior probability of the Resurrection is determined by a host of life experiences and theological insight and insight gained by prayer. For a Christian, belief in the Resurrection is consistent with massive knowledge about God and His grace. Belief in the Resurrection is not a "screening test" performed without any prior knowledge.

Still another point concerns the issue of justification that I raised earlier. Because a positive test result in the conditions I have described is far more likely to be wrong than right, the result fails to justify the belief that you have the disease. Even if you do have the disease, and even if the test correctly diagnoses you as having the disease, you should not believe this on the basis of the test alone. Forget about the test result. It’s as good as worthless as far as justification goes.
No Christian accepts the truth of the Resurrection "alone". The Resurrection is part of a living relationship with the One Who was resurrected.


Be that as it may, if Jesus’s resurrection is the ‘disease’ and the witness report is the ‘test’, we can now do the algebra to decide whether to believe in the resurrection. The base rate for the resurrection is (let’s say) one in 1 billion. The witnesses go wrong only one time in 100,000. One billion divided by 100,000 is 10,000. So, even granting the existence of extraordinary witnesses, the chance that they were right about the resurrection is only one in 10,000; hardly the basis for a justified belief. 
No one is justified in believing in Jesus’s resurrection. The numbers simply don’t justify the conclusion. But the resurrection is just one miracle. If we suppose that all miracles are similarly rare, then, by parity of reasoning, belief in any one of them is similarly unjustified. As noted earlier, my conclusion doesn’t deny that miracles have occurred or might occur, just that the available evidence fails to justify a belief that they have occurred. So, if you wish to continue to believe in miracles, you must do so knowing that the evidence is not on your side.
The prerequisite for an intelligent discussion of the warrant for belief in the Resurrection requires a genuine examination of the basis for the belief, which includes examination of the broad religious experiences of Christians. We are not doctors screening random patients for cancer. We know our patient intimately. Our belief in the Resurrection is part of a relationship with Christ, a relationship that we experience daily and that has profound ramifications in our lives.

Shapiro, like his mentor Hume, is blinded by atheism. They presuppose an atheist framework for belief in miracles, a framework stripped of genuine religious experience that serves as a predicate for belief in miracles. 

Presupposing naturalism, Shapiro and Hume infer naturalism. Big surprise.

There is another analogy that is much more appropriate to belief in the Resurrection than Shapiro's woefully inadequate cancer screening analogy. Imagine a man who loves his wife and longs to see her when she returns from a trip. He is waiting at the airport to greet her. As she walks out of the gate, he runs to hug her.

But did he have warrant to believe it was her? After all, as Shapiro/Hume would point out, there are seven billion people in the world, so the "screening" likelihood that that one person at the gate would be her is only one in seven billion. And it is certainly possible that the husband could be mistaken by a face in the crowd-- even if it's only one chance in a million that he would misidentify his wife.

By Lawrence/Hume's logic, the likelihood that the husband would embrace the right person is only one million/seven billion= 1/7000, or 0.014%.

By Lawrence/Hume's logic, the husband has virtually no chance of hugging the right person, his beloved wife.

But that's nonsense. The truth is that the husband knows his bride intimately, as she knows him, and he knows where and when to expect her, and he has faith that she will be there to embrace him at the airport gate. He is sure that he is embracing his beloved.

We Christians have such faith in our Beloved as well.

The Humean rejection of warrant for belief in Christian miracles, which has had enormous influence on our degenerate culture, is moronic junk philosophy.

Romans 1:22. 


  1. Commissar Boggs, Ministry of TruthApril 13, 2014 at 7:28 AM

    Excellent post Egnor. Nothing left to be said about that.

    But let's also remember a different kind of miracle - a miracle modeled by the fishes and loaves at Bethsaida. Another kind of "Daily Miracle".

    Today, this day, April 13, 2014, Catholic Relief Services will bring food, sustenance, and survival to millions of people in 91 countries. the food will be passed in bottles, baskets, barrels, bags, and boxes, gifts of agape love. Miraculously, tomorrow morning, the bottles, baskets, barrels, bags, and boxes will again be full and the loaves and fishes will be shared all around the world.

    The Body of Christ in the world today accomplishes this miracle, and it is so commonplace, so quotidian, such a part of "the way things are" that we lose sight of the truth that this bottomless gift - just as it was on that mountainside in Bethasida - is freely given, not coerced or stolen by a tax collector. And it is given to the least among us, not to the cronies, bundlers, and toadies of the powerful.

    For someone out there today, the best and greatest good news, the most wonderful gospel (Old English "gōd-spell"), will be the action that says much more loudly than words ever could, "You are loved."


  2. Egnor, atheists have a tendency to isolate Biblical miracles which nobody can test/observe and therefore cannot be proven either way (except by our faith, hence religion) while blatantly ignoring the modern-day miracles such as the incorruptible bodies of the saints, or the holy water spring at Lourdes, or miraculous healings, etc.

    Since Lawrence Shapiro is so fond of using *probabilities* in a (failed) attempt to disprove a spiritual event, would he be gracious enough to extend the same courtesy to the probability of life arising from non-life, which would be impossible, yet which atheists nevertheless believe to be fact?

    Herein lies atheism's true motive:
    "If God does not exist, everything is permitted." - Fyodor Dostoevsky

    1. Good to see you becoming a regular here, Michael. Good for laughs, that is.

      blatantly ignoring the modern-day miracles such as the incorruptible bodies of the saints, or the holy water spring at Lourdes, or miraculous healings, etc.

      Oh? How come a miracle never happens when a video camera is around? Why doesn't an amputees arm ever grow back - why does Jesus hate amputees so much?

      life arising from non-life, which would be impossible

      Last night's meal is now part of my living body. Non-life turned into life. It's a miracle.

      "If God does not exist, everything is permitted." - Fyodor Dostoevsky

      How come a random Catholic is 40 times more likely to end up in jail than a random atheist?

    2. I'm delighted that Michael is commenting regularly. He makes excellent points.


      There are many documented miracles. You simply refuse to look at the facts.

      Life arising from non-life is inexplicable by naturalistic (non-teleological) assumptions. Atheist miracles ("everything came from nothing,...", KW, are a far bigger stretch than anything in the Church.

      KW said: "How come a random Catholic is 40 times more likely to end up in jail than a random atheist?"

      Because, in communist countries, atheists ran the jails, and persecuted Christians massively and violently. Thanks for reminding us.

    3. Commissar Boggs, Ministry of TruthApril 13, 2014 at 10:01 AM

      troi: "How come a random Catholic..."

      You must be one hell of a scientist, troi. Are you at the University of Trollistan too? I always enjoy your statistical pseudopodia.

      Anyway, for those inclined to read troi's trolls, allow me to clarify his Daily Stoopid... those numbers reflect the religious affiliation claimed by federal inmates in 1997. In other words, it's one of those Spinning Internet Facts.

      Far from being a reflection what faith or a lack thereof might cause a "random Catholic" or a "random atheist" to do vis-a-vis the law, those numbers reflect the fact that a large part of the American prison population are black and Latino, hence Protestant and Catholic respectively. It's well-known that blacks and Latinos tend to live in Progressive Policy Paradises like Detroit, South Chicago, and South Los Angeles where crime is rampant, the family has been destroyed, and drugs are widely available.

      Also, in my opinion, the real reason for atheism was best expressed by the patron saint of atheists...

      If there were gods, how could I bear not to be a god?
      --- Nietzsche

      As it happens, Nietzsche's view coincides perfectly with Genesis 3:5, a fact I'm sure was not lost on Nietzsche.

    4. Thanks for the compliment Egnor. To all those who value their liberties, I would strongly suggest they read the humanist manifestos and other relevant material with regards to what these people desire to impose upon greater civilization, preferably with someone to cut through all the deceptive language and get right to the heart of the matter.

      Recommended reading:

      All the double-speak about diversity, tolerance and equal rights is a convenient false front to wage war upon our liberties and moral values. One only need look at the gross human rights violations, the genocidal campaigns committed in any of their communist utopias for an accurate representation of the "tolerant and equal" society they wish to impose upon western civilization. Indisputable fact: every single communist-atheist state has persecuted Christians, without exception. Is this what we really want, for America to fall into despotism a-la USSR, North Korea or Cuba?

    5. Sturmbahnfueher Boggs:

      Anyway, for those inclined to read troi's trolls, allow me to clarify his Daily Stoopid... those numbers reflect the religious affiliation claimed by federal inmates in 1997. In other words, it's one of those Spinning Internet Facts.

      In other words, facts you don't like. I dunno, perhaps an atheist is much, much less likely to become a federal inmate than a Catholic because atheists tend to be better educated and wealthier. Personally, I think the Christian theory that sins will be forgiven has been a huge impediment to ethical behavior.

      Far from being a reflection what faith or a lack thereof might cause a "random Catholic" or a "random atheist" to do vis-a-vis the law, those numbers reflect the fact that a large part of the American prison population are black and Latino, hence Protestant and Catholic respectively. It's well-known that blacks and Latinos tend to live in Progressive Policy Paradises like Detroit, South Chicago, and South Los Angeles where crime is rampant, the family has been destroyed, and drugs are widely available.

      Yes, the poor are more criminal. And of course the poor are more likely to vote Democrat, because the Democrats are more likely to assist the poor than the Republicans are. You seem to turn it upside down and suggest that Democrat policies encourage crime.

    6. troy, how do you know that many of the inmates aren't really atheists calling themselves Christians? You don't know. In order to be a Christian requires obedience to God's law, not merely calling oneself Christian. (That all being said, God's Mercy is open to all.)

  3. Egnor's argument rests on his extraordinary claim to have met Jesus and doesn't even rise to the level of sophistry.

    Egnor's man at the airport analogy for Shapiro's argument is so obviously wrong that I suspect that it was designed for dumb Christians eager to accept any argument that supports their belief. For the dumber among you let me point out that the 7 billion people of the world don't appear on airplanes at random. The husband is only at the airport because he knows his wife bought one of the limited number of tickets for that flight.

    Oh, and Egnor, you should be addressing Troy above, not me.


    1. You make my argument for me, KW. The man knows his wife at the airport because of the totality of his knowledge-- he knows her, he knows what she does, where to find her, etc.

      We Christians know Christ.

    2. "The husband is only at the airport because he knows his wife bought one of the limited number of tickets for that flight."

      Isn't that Egnor's point? Ignoring the context of the wife's return trip is like Shapiro ignoring the context of Christian belief.


    3. No, I refuted your dishonest analogy to Shapiro's argument. That you continue to be dishonest by somehow claiming that I'm actually making your argument for you is no surprise. Since you are so obviously willing to lie in defense of your beliefs, why should anyone believe your extraordinary claim that you have met Jesus?

      You are exhibit A of how strong religious faith turns people into delusional lairs.


    4. Citizen Boggs, Committee of General SecurityApril 13, 2014 at 10:21 AM



      I think you got readiated by them nookalar reactionaries.

    5. No Curio, To make Shapiro's argument match Egnor's analogy Shapiro would have to have left out the fact that the diagnosed person didn't get the disease randomly, but where instead exposed to circumstances that made it almost certain that they get the disease. Either Egnor isn't nearly as smart as he thinks he is, or he's intentionally being deceptive.

      Here's a case where his reasoning is obviously wrong. I would be pleasantly surprised if he admits his error in logic, but because I suspect he's being intentionally deceptive I won't hold my breath.


    6. Citizen Boggs, Committee of General SecurityApril 13, 2014 at 10:31 AM

      Popster, you have your little neutrons at work today! Your insites are unparalyzed in the history of this blog.

      I love ya, Pops. I really do.

    7. I must admit, it's amusing watching the moral relativists pretend to hold the moral high ground and talk down on the rest of society.

      You've got to appreciate their stunted logic that states that those of us who hold to traditional morals and values, as were held by every civilization of prosperity for thousands of years, are now classified by the self-imbued "moral authority" PC thought police as haters and bigots.

      Liberal *logic* 101
      Don't believe that sodomy is on par with male-female sexual relations? HATER!!!
      Don't believe that the universe was self-caused and that life was the result of random events? BIBLE-THUMPING IDIOT!!!
      Don't agree with Obama, Holder or anyone else who's not white? RACIST!!!

      The progressives are always right because they decided that they're always right, don't ya know? Pay no attention to their deceptive word games, creative tinkering with morals and social norms, penchant for double-speak, suppression of speech they deem offensive, overruling popular referendum when it suits their interests, and purging of heretics who commit thought. Their insane ideology must take precedence at all costs.

    8. Egnor,

      Your analogy of a husband recognising his wife in a crowded airport because he 'knows' her isn't a very good one. Humans are very good at recognising individuals - at least from populations with which they're familiar (more later).

      I regularly recognise casual acquaintances whom I haven't seen for years at concerts (and attach the correct name - despite my poor memory of names). And once I identified immediately a person I knew just working at the same hospital - in a gift shop at the so-called Nottingham Castle on the other side of the world. Completely unexpectedly.

      People aren't good identifying individuals from populations they're not familiar. Matt Taibbi in his latest book 'Divide' (strongly recommended) gives an example. A Vietnamese man was on trial for murder in a town in America, and for 2 days he protested in broken English that he didn't do it whenever a witness identified him as the murderer. Eventually, it turned out that the bailiffs had brought the wrong Vietnamese from the holding cells (he actually was there accused of robbery) and he was protesting that he was the wrong person. In the retrial, the accused was convicted despite the witnesses being just as certain that the Vietnamese in the mistrial was just as guilty...

      You're in the analogous position as the witnesses in the mistrial of the wrong Vietnamese defendant. You think you know Jesus and you think you recognise him in your thoughts, but it's all just wishful thinking.

  4. Lawrence: "No one is justified in believing in Jesus’s resurrection"

    Isn't it ironic that the word "justified" is being used in this debate?

    Justification really is the heart of the matter. God says we are "justified" when we believe in the resurrection. Who are you going to believe? God or some athiest?

    Romans 10:9 "That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved."

    1. Awstar,

      Personally I prefer to believe someone who can actually spell 'atheist' correctly instead of 'athiest'.

      Anyway. Romans was written by Paul. Not God.

    2. God is speaking to us through Paul's writings. But if you rather hear it from a more direct source:

      "Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life." -- John 5:24

      For someone who believes we have evolved from apes through genetic typo's, you're rather picky.

    3. Awstar,

      'John' was written by someone who was later ascribed to be a John, not by God. We don't know if Jesus said what he's supposed to have said, and even if he did, was inspired by God.

      It's a circular argument to quote scripture to 'prove' scripture.

      We didn't evolve from apes. We are apes. Even the creationist Carl Linnaeus recognised that in his classification.

    4. bachfiend,

      I'm not trying to prove scripture. believing scripture as the inspired Word of God is my starting axiom. Just as yours is that evolution is true. Neither of us needs to prove our respective starting axiom. We just need to live out the consequences of trusting in it.

    5. Awstar,

      I didn't have evolution as my starting axiom. I came to accept evolution as being true (to the limits of science, which always is provisional subject to revision) based on the evidence.

      If I accepted scripture as being inspired by God instead of being the obvious product of fallible albeit understandable humans, I wouldn't be an atheist.

  5. I'm wondering if the Bayesian angle is just fluff. Someone tell me if this isn't Shapiro's argument, reduced to its simplest form...

    M: Miracles are highly unlikely
    m: We shouldn't believe in things that are highly unlikely
    c: We shouldn't believe in miracles


    1. Curio,

      That's not Bayesian. You need to make an estimate of the probability of miracles occurring, add an observation and assess how this observation affects the probability of miracles occurring - whether it increases or decreases the probability.

      With miracles:

      Suppose the probability of a miracle occurring is 1 in a million (say the Resurrection - we've never seen someone come back from the dead to the extent of walking around on the 3rd day)

      Then we assess the probability of people lying or just getting what they observe wrong. Christians think that the Gospels are 100% true. Atheists just note that people do lie. Eyewitnesses often are wrong.

      Christians therefore increase the probability of the Resurrection. Atheists decrease it.

    2. That's the logical problem with using Bayes' Theorem for historical probabilities. If you don't "like" the history, you just say, "...people do lie. Eyewitnesses often are wrong." Then you get to calculate the very low probability which allows you to deny that it ever happened. Pure prejudice, without any actual knowledge or truth or fact involved.

    3. Stan,

      Bayes theorem just offers a way of assessing whether new observations increase or decrease prior probalities. Curio characterised it without the new observation. You can add more than 1 new observation sequentially.

      For example, you could add the observation that people often lie and or are honestly mistaken, reducing the probability, and then add the observation that the Bible is reliable on many things, and hence is reliable on the Resurrection to some degree, increasing the probability.

      I know people lie or are honestly mistaken. You have to justify that the Bible is reliable.

      Bayes' theorem doesn't disprove anything - just makes them more or less likely. Miracles could still happen.

    4. Bachfiend,

      I know the syllogism I gave isn't Bayesian. Shapiro himself admits the entire argument is unoriginal - taken from Hume's famous treatise on miracles. The only original component is that it's restated in Bayesian terms.

      There's an extended reply in the comments section by user James Savage. It's worth reading. I'll block quote a relevant section from his exchange with another commenter on the utility of priors in this debate

      "Let me explore the deeper issue with your claim. If the base rate is zero - then no finite amount of evidence can ever change your posterior (I'll set aside the mathematical issues of infinite evidence with a degenerate prior). That is, you have ruled out the possibility of justified belief in miracles from the start. That is a perfectly fine position to take, but that cannot then be the basis for arguing that justified belief in miracles is impossible. You would then need to argue WHY the prior should be zero. You're almost making a definitional claim at that point ("there can be no married bachelors") if the prior is actually a hard zero.

      Either way, if the prior is extremely small, that is what is doing all the work in the argument. You've simply buried the debate."


    5. Bach,

      It's also worth noting that Shapiro isn't arguing just for belief in the Resurrection being unjustified... but rather all miracles. This James Savage character correctly points out that an argument for the former is not a valid argument for the latter.

      I agree with Carl Sagan, extraordinary claims require extraordinary evidence... however we would all be wise to see if our presuppositions affect our priors. And the most dangerous presuppositions are the ones we don't even know we hold.