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Religion and Skepticism: Can (and Should!) Skeptics Challenge Religion?*

By Lucia K. B. Hall and Norman F. Hall

I. Probability and science

We believe that skeptics not only have the ability to challenge the claims of religion, they have the right and duty to do so. In order to support this contention, we will begin by claiming that the following statements are true: (1) the earth is flat; (2) UFOs are piloted by aliens; and (3) evolution doesn't happen.

What, you skeptics don't agree with them? But they are all true -- to within a certain range of probability. The earth is flat enough that you don't have to take the curvature into account when building a house, for example, or even a city. If you don't extend your measurements beyond a few hundred miles, the first statement is true. But if you go far enough, and measure carefully enough, you not only begin to notice some curvature, you find you can go all the way around it.

And so we skeptics claim the earth is a sphere. But even that is only true within a certain range of probability. Careful measurements show the earth's spinning distorts its shape a little, bulging it out at the equator and squashing it at the poles, making it an oblate spheroid. Even more careful measurements show the earth to be a bit pear-shaped. So, the earth is more spherical than flat, more oblate than spherical, more pear-shaped than oblate. The probability of the earth being flat is in fact quite low.

The other two questions can be taken care of in the same way. If you don't look too closely or carefully, every UFO could be piloted by little green men. But, on closer examination, most UFOs turn out to be either strictly terrestrial, or boring extraterrestrial objects like Venus or meteors. To a high probability, so far, UFOs lack little green pilots. Of course, the third statement is true. And here's the proof: no person reading these words is evolving! (We will leave it to you to demolish that argument.)

The above statements are "true" (or at least not absolutely false) because no probabilistic argument can be taken as ironclad, absolute proof. "Very, very unlikely" is not the same as "never." There is still a vanishingly small possibility that the earth really is flat, UFOs really do have little green pilots, and evolution is "just a theory." After all, there is no reason to expect ahead of time that any of the above statements are necessarily impossible, even though they have been shown, to ever higher probability, to be false. But, while honest skepticism must begin its examination of all claims without prejudice, and approach each claim with neutrality as to its truth or falsity, we don't need to keep our minds so open that our brains fall out. If the same claim has been repeatedly tested and been found wanting, there comes a time when it is merely perverse to continue to believe in it. At some point, properly gathered evidence, even negative evidence, must be sufficiently compelling to allow us to discard some claims, at least as working hypotheses.

How much evidence is enough? How likely a claim is can be quantified by the evidence for or against it. The technique is called Baysean reasoning. It is a quantitative way of calculating what most people do informally when deciding the probabilities of a claim, by adding up the evidence for or against a particular claim. The equation looks like this: P (Hi|D+I) = P(Hi|I) x P(D|I + Hi) ö P(D|I) where P = probability, Hi = hypothesis, I = initial information, and D = newly observed data.

To evaluate a claim, one begins by assuming a neutral probability (P = 50%, for instance), and then evaluates newly observed data as follows. The probability that the hypothesis (Hi) is true, given both the newly observed data (D) and pre-existing information (I), equals the probability that the hypothesis is true given only the previously known information, times the probability of observing such an outcome (D) assuming our previous knowledge (I) and also assuming that the hypothesis is true (Hi); all divided by the probability that such a piece of data (D) could be expected to be observed given ONLY the previously existing information (I). While one positive example can bring the probability of the claim to one, as more and more negative evidence is gathered, the probability of the claim being true asymptotically approaches zero. The point is that negative evidence is not meaningless, and it does change the probability of the claim.

If you assume at the start that something has a probability of one, that is, if you assume it is certain, no amount of further information will change that probability. But for the skeptic the Bayesean approach permits us to recognize that, while nothing is certain, a mountain of negative evidence cannot be ignored. Certain extraordinary claims, for which positive evidence never surfaces despite repeated attempts to find supporting data, become increasingly less likely to be true. The point at which it becomes perverse to still harbor hope for such claims must rest, at least partly, upon personal taste. Two people, looking at the same data, depending on how they weigh each contribution to the calculation, can come up with opposing conclusions.

It is clear how Baysean reasoning can be used to evaluate the three above claims. But what about the following statement? (4) God listens to our prayers and causes miracles to happen. Can this statement be treated in the same fashion as the other three? It seems, at first blush, quite different from the others Sand, in one important aspect, it is different from them. Why that is the case we will consider after we discuss the difference between science and skepticism.

II. Science, Naturalism, and the Postulate of Objectivity

Pure skepticism begins without prejudice. Science also begins from this position; anything regarded as true or false from the outset cannot be tested. However, unlike pure skepticism, science has found it useful to make one additional assumption about the universe. It is what Jacques Monod called the postulate of objectivity. The term is unfortunate. It sounds as though scientists must be "objective" about the universe, or that it's possible to discover "objective truth." Neither is the case. What Monod meant was that the universe itself is objective, that it tells us the truth about itself (it does not deliberately deceive us or work one way for certain people and a different way for others). One necessary corollary of this assumption is that if the universe is being honest with us then the only way we can find anything out about it is to be honest with it. All scientists have to make a commitment to this ethic of truth-telling. If you don't tell the truth, your science is no good.

Another necessary corollary of the postulate of objectivity is the assumption of naturalism. In order to do science, to subject the universe to the rigors of controlled experimentation, you have to assume that uncontrollable, unaccountable powers either do not exist or, if they do exist, do not interfere. In particular, interference by supernatural powers is not allowed. If such interference were possible, then all attempts at controlled experimentation become either impossible or pointless. This is naturalism in its broadest sense, and while it does not absolutely rule out the existence of the supernatural, it puts a severe limit on the possible kinds of powers that can be allowed in a universe in which science has been found to work.

What is important here is that every scientific experiment tests, not just the particular physical question under study, but all the experiments that came before. Thus the ethic of truth-telling, naturalism, and the postulate of objectivity are tested each and every time an experiment is conducted. In fact, the postulate of objectivity and its corollaries are the most-tested hypotheses in all of human history, and they have not yet been found to fail.

III. Concerning the Existence of God

Now let's look again at statement four. If we treat statement four the same way we treated the other three, if we treat the notion of a god who interferes in human affairs as an hypothesis, it should be obvious that the continued success of the postulate of objectivity and its necessary corollaries should be considered overwhelming evidence against the existence of any god who causes miracles or listens to prayer. It is, of course, negative evidence, and subject to refutation from a sufficiently compelling positive example. But it should be clear that the probability that a god or other supernatural force either exists or interferes with the universe is vanishingly small, and getting smaller. If the idea of god were treated honestly, as an hypothesis about the nature of the universe subject to Baysean analysis, it would have been discarded long ago.

Of course, this will never happen. Statement four is different from the other three because god is not treated as an hypothesis. The existence of god is a given truth with a probability of one, and science must simply muddle along somehow. In such a universe, science works when god wants it to, and doesn't work when he doesn't want it to, and all the commentary on Baysean reasoning and all the negative evidence from all the scientific experiments ever done make no difference.

Has the success of the postulate of objectivity and its corollaries disproved the existence of all possible gods? Not at all. A god who does nothing (the deist god), or acts completely randomly (Arthur Peacock's claim), or even acts according to a carefully coordinated program of deceit (the omphalos argument), is a god you can't refute. It is hard to see what use such gods would be, and they are supremely vulnerable to Occam's razor, but they could still exist. Of course, most people find such gods either too limited, disappointing, or ghastly to be believable. Most people want to believe in a god who acts with a direct purpose, who listens to prayers, who works miracles, who sends angels to earth. They want to believe in a god who not only invented nature and everything in it, but who can interfere with it at will. That it is precisely this sort of god that science has exhaustively found to be very, very unlikely concerns them little if at all.

Quite a number of scientists without an understanding of the above realizations have made fools of themselves concerning the issue of god. For example, Stephen Jay Gould, in his recent book Rocks of Ages, insists that we separate the realm of science and the realm of religion into two "magisteria," separate but equal realms of power and proper behavior. The proper realm of religion is ethics, while the proper realm of science is everything else. But where does this leave the ethic of truth-telling, the commitment to honesty all scientists must make in order to do science at all? Is that commitment part of science, or part of religion? Besides, just about everything else religion has claimed to be true has been shown to be highly unlikely, if not out-and-out wrong. Why are we to be forced to accept its pronouncements on ethics?

Eugenie Scott, on the other hand, does not separate science from religion, but merely claims that science is unable to answer the one, ultimate question of whether or not the universe has a purpose. After all, that sounds like something that's outside the realm of science, doesn't it? We don't really know that the universe is based on the postulate of objectivity, do we? Shouldn't we allow religion special pleading in this one case? Yes, but only if we want to assume that the laws that work inside the laboratory are different than the ones that work outside of it, that what science discovers about the world can have no bearing on the nature of that world, and that naturalism, truth-telling, and the postulate of objectivity are only "methodological."

IV. Oh, No! We're Bashing Religion!

Now we've done it. We're bashing religion. How dare we treat god as an hypothesis? How dare we challenge the claims of religion? How dare we take this idea of the ultimate and ask it to pass the same tests of evidence as everything else?

We dare because we don't have any other choice, not if we want to remain honest with ourselves. As skeptics, as scientists, we can't assume from the start that god has a probability of one (or a probability of zero, for that matter). And if pointing out that the postulate of objectivity is highly probable and the god-hypothesis is highly improbable is bashing religion, then so be it.

But we're pretty sure that what we have to say here will not disturb anyone's religious beliefs in any way. Neither faith in god nor religious belief depend on evidence, whether negative or otherwise. Statement four is never treated the same way as the other three, not by believers and, unfortunately, not by many skeptics, either. It is always taken as a special case, a necessary exception, to all the rules that govern the rest of reality. And as long as god is never taken as a testable hypothesis, as long as there are people who, like Stephen Jay Gould and Eugenie Scott, declare that religion deserves the right to special pleading, nothing we say will have any effect whatsoever. God is quite safe from our puny attacks.

So why do we bother? Because there is another, deeper, more personal and even emotional reason why we dare. It seems to us that the two things necessary to make life meaningful for human beings are love and purpose. Someone else once said the two most meaningful things are love and work, but we don't think he meant work in the sense of being a wage slave; purposeless work is sheer torture. We think he meant work in the sense of working for a worthwhile purpose that you value. But as long as we continue to be told that love and purpose are not to be found in the natural world, and must be found in the supernatural, then both pseudoscience and religion will persist. Religion tells us that life without god is meaningless; that god is love; that our only purpose is to worship him; that the material world is worthless. But as long as only god's love is valued, human love will mean nothing. As long as the only allowable purpose is to worship god, then human purposes will have no meaning. Living in this world in the here and now; loving those people and creatures who are in it for themselves; and trying to understand the world honestly, on its own terms, will have no value. Religion and the supernatural are a classic bait-and-switch scheme. You go to them, trying to find the answer to life, and you are told that life is not the answer. We feel this is a tragedy.

We do not intend to devalue the meaning religion gives to people's lives. The need for love and purpose seem to be vital for both human survival and human dignity, and to denigrate that need is cruel and dishonest. But we do feel constrained to point out that this need is so strong that people are quite capable of believing in the impossible to fill it.

V. The Toleration of Science

If all of the above is true, it would seem that the evidence of science leads inevitably to atheism, perceived by this society as the worst possible evil. So why is science tolerated? Partly because people are profoundly ignorant of even the findings of science, let alone the deeper assumptions that allow science to work. Partly because people do not see the process of testing the postulate of objectivity, the assumption of naturalism, or the ethic of truth-telling that are central to the scientific method, but only the findings themselves. They don't care how the latest technological innovations got here; they just want the goodies. The findings of science are for sale on every street corner while the method of science languishes in obscurity. It isn't that scientists are being robbed blind, although they are; the real tragedy is that humanity is being robbed of the opportunity to understand why scientists become atheists.

Heroic scientists such as Bill Nye, James Randi, Richard Dawkins, and Carl Sagan have attempted to bring science to the attention of the public, to encourage critical thinking, to replace the "wonder" of religion with the "wonder" of science. But most people don't want to know the truth that science has revealed as being highly probable. They want the comforting lies, the delightful fantasies, the mysteries, the pseudoscience. All people ever see of science is the special effects, and it's all they ever want to see. The truth is simply too inconvenient.

So why is science tolerated? Because it is confused with magic. It's amazing how much of science has been used to satisfy people's fantasies and fairy-tale desires. We have seven league boots and flying carpets (planes, trains, and automobiles); magic swords (AK-47s, nuclear weapons, and ICBMs); crystal balls (telephones and televisions); and mystic oracles (computers and the internet). But science is not magic, and never will be. The technological goodies of science are almost entirely peripheral to the enterprise of science. The purpose of science is to tell the truth about the way the world is, not fulfill people's fairy-tale desires. As long as human beings want fairy tales to come true, science will fail to measure up. This will cause discontent. The latest rumblings of that discontent can be heard in the disaffections of both the political left (postmodernism) and right (fundamentalist religions). At some point people will learn that they can't have everything they want.

What will happen when people realize that providing more toys and power is not the purpose of science and that the wonders they already have come with real-world limitations and consequences for their use? In the real world, wonders come with a price tag. What happens when the bill comes due? First, there will be massive denial that there's even a bill to be paid. Magic is not supposed to cause pollution, or use up or destroy irreplaceable resources, or be limited by physics, the laws of thermodynamics, or information theory. Then, when scientists tell people the truth, as they must, all those folks who have misunderstood the purpose of science all along will feel betrayed. Scientists are supposed to be wizards, not make mistakes or have limitations. If science doesn't work the way people want it to, then it is the fault of science. And, since science is defective, then the answer has to be found elsewhere, in pseudoscience, religion, "alternative" medicine, and whatever nonsense claims to be a better magic.

VI. So why tell the truth?

It seems that, faced with this sobering situation, the best thing scientists can do is to keep quiet about their atheism. Almost all of them do. It seems a far better, humbler, and safer course to follow the lead of Gould and Scott, and cloak the wolf of science in the lambskin of religion, the shining robes of magic and fantasy, to make it appear harmless, to take the safe way out, delicately questioning only the edges of the supernatural, the simple claims of spoon-bending and dowsing, and leave the far deeper supernaturalism of religion alone.

We have some sympathy for this viewpoint. We would be fools to underestimate our adversary. To challenge religion is fatal in many parts of the world, and seriously dangerous just about everywhere. But if we follow this safe road, we are the dupes of that same ancient, grasping, greedy and deadly power that wants to be declared right, at whatever cost. That power is ignoring us for the moment. But we'd better not fool ourselves as to its central intent, which is to squash all dissent and freethought in favor of wishful thinking. The Catholic Church fights for rights of the poor and oppressed to become good believing Catholics, not questioning atheists or fearless scientists. Protestant religions fight against new age beliefs because they consider them competition, not because they value science or critical thinking. The only reason communism is atheistic was because, as a new religion, as the revealed word according to Marx, it was forced to distinguish itself from the other religions, not because it valued science. And this is all done with real or pretended nobility of motive which, sadly, is where most evil is to be found.

We live in a golden age that many believe will go on forever. People don't want the fairy-tale to end. Far from showing any signs of facing up to the limitations of what the postulate of objectivity, the ethic of truth-telling, and naturalism tell us about the world, people show every sign of running ever deeper into comfortable fantasies. But it isn't possible. Reality works according to its own rules, not our desires.

So why tell the truth about science? Why annoy people by telling them that their god is highly likely to be untrue? Haven't we got enough problems already? Because if we don't tell what we have learned here, now, in the only place and time, in the history of the world it has been possible to tell it, when and where should we do it? Do we want to tell truth in the middle of a golden age, when science is still a highly respected profession and people might have the time and inclination to consider it, and even, just possibly, get used to the idea? Or do we want to try to explain it after we are blamed for the failure of society to heed our warnings?

The human race will ultimately survive only if the limitations to all human knowledge are understood and accepted. We must tell the whole truth, now, before mankind's belief in magic, god, and the supernatural, coupled with the tremendous power of scientific technology, lead to horrible disaster. The phrase "godless science" must cease being an epithet and instead become a simple, even redundant, statement of fact. And we, as skeptics, as scientists, as atheists, must stop feeling ashamed about expressing and supporting the most tested hypotheses in all of human experience.

We would like to end with a quote from Jacob Bronowski's Ascent of Man:

"It is said that science will dehumanize people and turn them into numbers. That is false, tragically false. Look for yourself. This is the concentration camp and crematorium at Auschwitz. This is where people were turned into numbers. Into this pond were flushed the ashes of some four million people. And that was not done by gas. It was done by arrogance. It was done by dogma. It was done by ignorance. When people believe that they have absolute knowledge, with no test in reality, this is how they behave. This is what men do when they aspire to the knowledge of gods."

As long as belief in god is treated not as hypothesis, but as a certainty above criticism, as long as religion is the one area of human thought exempted from the effect of negative evidence, as long as ethical systems are allowed to ignore the highly probable limitations of the postulate of objectivity, this is how humans will continue to behave. We have the responsibility, the duty, and the right to challenge arrogance, dogma, and ignorance. Go now, and tell the truth!

* This article is a synopsis of a lecture presented by the authors at the SDARI meeting on May 23,1999.


Lucia K. B. Hall is the President of the Humanist Association of San Diego. Norman F. Hall is Southwest Liaison Officer of the National Ocean Data Center; both are members of SDARI.