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Jul 21 2011

The logic of science-7: The burden of proof in science

(For previous posts in this series, see here.)

The logic used in arriving at scientific conclusions closely tracks the legal maxim that ‘the burden of proof rests on who asserts’. It should be noted that the word proof used here does not correspond the way it is used in mathematics, but more along the lines used in law. As commenter Eric pointed out in response to the previous post in this series, in the legal arena there are two standards for proof. In criminal cases, there is the higher bar of proving beyond a reasonable doubt, but in civil cases the standard is one based on the preponderance of evidence. So if the preponderance of evidence is in favor of one position, it is assumed to be true even if it has not been proven beyond a reasonable doubt. Scientific propositions are judged to be true not because they have been proven to be logically and incontrovertibly true (which is impossible to do) or because they have been established by knowledgeable judges to be beyond a reasonable doubt (which is not impossible but is too high a bar to result in productive science), but because the preponderance of evidence favors them. Evidence plays a crucial role here as it does in legal cases.

Scientific claims can be both existence claims and universal claims, and these two types of propositions are proved in different ways. In science the burden of proof in existence claims lies, as in legal claims, with those who make the claim. If they cannot meet the standard of proof, the claim is presumed to be false. With universal claims however (once at least some positive evidence has been provided in support of existence), the burden of proof lies with those trying to show that it is false. In the legal context, a witness who swears to tell the truth is assumed to be always telling the truth, a universal claim. A lawyer who wishes to make the point that a witness is not truthful is the one who is assumed to making an assertion and thus has the burden of proof to show that the witness has lied.

For an example of proof of an existence claim in science, the claim that an entity called an electron exists has to be supported by evidence that shows that an entity with the postulated properties of an electron (such as its mass and charge) has been, or at least can be, detected in experiments. The reason that I say ‘can be’ is that in some cases if there is strong circumstantial evidence in favor of the existence of an entity, a provisional verdict in favor of existence may be granted, pending more direct confirmation. The most famous case of this may the ‘ether’, which was postulated to exist on the basis of circumstantial evidence that it should exist, until it was shown that the theory of relativity undermined all that evidence in its favor and its existence was rejected. The neutrino is example of something that was granted provisional existence and was later directly detected.

The reason for these rules about how to judge the truth of existence and universal claims is simply because without them science would be unworkable. In most cases of scientific interest, it is impossible to prove that an existence claim is false and without these rules we would be swamped with existence claims for non-existent entities. The film Avatar, for example, postulated the existence of a valuable mineral called Unobtainium on another planet called Pandora somewhere in the universe. How could one possibly prove that such a mineral (or even the planet) does not exist? One cannot. Thus originates the scientific rule that to establish that a proposition of existence is true, one has to provide positive evidence in support of it. In the absence of such evidence, a perfectly justifiable scientific conclusion is that the proposition is false and that it does not exist.

This rule is hardly controversial. It is used in everyday life by everyone because would be impossible to live otherwise. To not have such a rule is to open oneself to an infinite number of mythical entities. To allow for the existence of something in the absence of a preponderance of evidence in support of its existence means believing in the existence of unicorns, leprechauns, pixies, dragons, centaurs, mermaids, fairies, demons, vampires, and werewolves.

This is why it is perfectly valid to conclude that there is no god. ‘There is a god’ is an existence claim and the burden of proof lies with those making the claim. Since no one has produced a preponderance of evidence in support of it, the claim is not to be taken seriously. Religious apologists who try to argue that god exists using logic alone without producing a preponderance of evidence in its favor are not being scientific and have entered the evidence-free realm of theology, in which one starts with whatever one wants to believe and then manufactures reasons for believing in it, even if that same reasoning is not applied to any other sphere of life.

Religious ‘logic’ is beautifully illustrated by this cartoon.

religiouslogic.jpg

Next in the series: The power of universal claims in science

16 comments

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  1. 1
    healthphysicist

    Here’s Eugenie Scott with the National Center For Science Education explaining why science has nothing to do with atheism or theism:

  2. 2
    Mano

    My response to Eugenie Scott would be my New Humanist article.

  3. 3
    healthphysicist

    Professor -

    I’m not seeing much of a connection, between Scott’s claim that science has nothing to do with atheism/theism and your article which seeks to redefine what an “atheist” is.

  4. 4
    Mano

    Because my article argues that the way we determine in science whether something exists or not will, if applied to god, lead us to conclude that god does not exist.

  5. 5
    healthphysics

    But that is ignoring Scott’s point, not addressing it. Scott’s point is that science’s methodology is too constrained to do that.

  6. 6
    Mano

    I am directly addressing her point.

    The whole point of that article (and this post) is that science’s methodology allows us to assert that all manner of things don’t exist. Why should the existence of god be any different? What is it about the methods of scientific reasoning that allows us to say that “the ether does not exist” but not that “god does not exist”?

  7. 7
    healthphysicist

    Because ether was claimed to be within the Universe, but God is claimed as not within it.

  8. 8
    Eric

    HP –

    What is the point of claiming that something exists “not within” the universe if we have no conceivable method of detecting things outside of the universe? It is just as true (and just as pointless) to claim that invisible polka-dotted unicorns exist “outside the universe.” The claim is literally irrelevant to anything.

  9. 9
    healthphysicist

    To a theist, the Universe is evidence of God and God is outside the Universe. It is very relevant to them, and apparently to those atheists who are busy discounting them.

    The theists don’t care about polka-dotted unicorns. They don’t care about detecting God…they have faith.

  10. 10
    Mano

    Ah, the old “god is outside the universe” ploy, as Inspector Clousseau would say!

    This is usually the last resort of people who realize that science has squeezed god out of the picture but inexplicably want to cling on to belief.

    I would bet that very few theists would sign on to this idea because the appeal of god is of someone who can actually do stuff in this universe, answer their prayers, and so forth. A god who is outside the universe is of no use to them. What would be the point? Such a god has as much influence on their lives as Eric’s invisible polka-dotted unicorns

  11. 11
    healthphysicist

    “Ah, the old “god is outside the universe ploy…”

    That’s the point. It is old and goes back to Maimonides and Aquinas, if not before. Nothing has really changed since. Any Christian or Jewish theologian knows this. That is why they laugh at the “science” argument. Science has nothing to do with it.

    “A god who is outside the universe is of no use to them. What would be the point?”

    Obviously that’s false. Jews and Christians espouse the work of the scholars mentioned above. They do find a point. You don’t (nor I), but they do. If god created everything then what more influence on one’s life could a god have?

    Projecting your sense of what god means to a theist is just as erroneous as when a theist projects what atheism means to an atheist (no sense of purpose, no morals, etc.).

  12. 12
    Mano

    I doubt that you would find many theists who would accept the idea that god is outside the universe because that would mean that the Bible and Koran and other religious texts are false since they describe a god who is manifestly active in the universe. I have moved around in Christian circles all my life and I have yet to meet a single churchgoer who actually thinks of god in this way. They may have heard the name of Aquinas and think he must have been a great thinker but have little idea of what his ideas are, the same way many think of Plato or Wittgenstein.

    The only people who think of god as outside the universe are theologians desperate to salvage the idea of some god somewhere, even if he has nothing to do with the universe.

    Incidentally, I would be delighted if all religious people started believing in a god outside the universe that had no influence whatsoever in our universe, and threw away their religious texts because they could not then be the word of god. There would be no point in quoting religious texts in support of any position.

    Such a useless god would be the functional equivalent of no god.

  13. 13
    healthphysicist

    So do you think that a vast majority of modern, religious Americans are completely unaware of science?

    Nationally, 70% of Americans believe in God.

    Broadkly, they either ignore aspects of science (religious text fundamentalists) or they don’t take the religious texts literally, with God outside of the Universe.

    And then there are the religious scientists who clearly understand that science plays no role…Collins, Polkinghorne, Schroeder, etc. And then there are the atheists who understand that science plays no role…Scott, myself, etc.

    An analogy for me is to compare the Universe to a Jackson Pollack painting (those unfamiliar should Google)…science can tell us the size of the painting, the colors of the painting, what the paint and canvas are composed of, etc.

    They don’t tell us whether the painting is art or not. And certainly scientifically examining the painting says nothing about Pollack.

    Someone who loves the artistry of the painting might treasure it, and have troves of respect for Pollack. They might pay large sums of cash for a painting. Someone who sees no artistry, won’t give it a second thought, and wouldn’t pay a dollar. Either way, the science is impotent.

  14. 14
    healthphysicist

    (A further thought, as I have to leave)

    It sounds like you are an a-Scripturalist, which is certainly warranted by science. I was an a-Scripturalist as a pre-teen, it was obviously full of myths and contradictions. Science is the nail on the coffin.

    It is interesting to review how coming out of the Middle Ages, Catholicism had fractured, and then Protestantism fractured. The earliest natural philosophers, where Christians, trying to overcome the lack of explanatory power in the Scriptures. They fully expected to find insight on the best Scriptural interpretation based on what they learned from Nature.

    They were surprised to learn that Nature itself provides better insight into reality than Scripture. Even a religionist who attempts to re-interpret Scripture, has to admit he/she’s is using Naturalism to do so.

    That fight has been won.

    But that is still different than atheistm/theism.

    Have a good day!

  15. 15
    Mano

    70% of Americans may believe in god but almost all definitely do not believe in a god that is outside the universe.

    Collins and Polkinghorne may say they believe in a god who is outside the universe but they also believe that Jesus is the son of this god and he rose from the dead. How can they then claim that science plays no role in evaluating their god claims?

    The art issue seems to me to be tangential to this question. This is not a question of appreciation of the idea of god or whether it offers comfort or solace.

    It is whether science can say anything about a god, as envisaged by almost believers as someone who is involved with life in this universe, exists at all.

    Science can and the answer is no.

  16. 16
    baal

    I love your argumentation Mano. It’s very concise and strikes at the right point.

    I do agree with you on the practical impacts of proof in legal proceedings but I’ve a Masters in Biology (a going away present, I had enough of the PhD program and left) and a J.D. (secondly and still in the law community). Attorneys are very happy to not need to establish proof to the level required in the science setting.

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