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Posted by on Aug 23, 2012 in Religion | 10 comments

You know how they say that absence of evidence is not evidence of absence? They’re wrong.

OK, I went a little too far, they’re not always wrong. The statement would be more accurately phrased as follows: Absence of evidence is evidence of absence, but not proof. Disagree? Let me explain.

The following exchange between atheists and believers seems quite common:

Believer: How do you know there’s no God?

Atheist: There’s no evidence for a god.

Believer (smugly). Yes, but absence of evidence is not evidence of absence.

Aside from the fact that the burden of presenting evidence lies with the person making a positive assertion, there are several problems with this exchange. First, there’s the erroneous assumption that all atheists know there’s no god. Although I imagine that there are a few atheists who believe that they do, most, if not all, are open to new evidence. That’s what distinguishes (or should distinguish) us from believers. Persuasive evidence of a god or gods should change our minds. I know that if he takes out his thunderbolt and smites me, I’ll believe in god for sure.

Second, absence of evidence is conclusive evidence in cases where evidence would be expected. For instance, you can assume that your window wasn’t broken while you were out when there’s no evidence of a broken window when you return. Or you can conclude that it didn’t rain during the five minutes you spent inside a grocery store if you come out and the ground shows no moisture. You know that there’s no pink hippopotamus in your room because there’s no evidence of one, and you can be sure that a giant meteor didn’t destroy the earth last night because the earth is still here. I can probably get more ridiculous with my examples, but I think you get the point. So how does this relate to the belief in god? When it comes to theist gods, there are assertions in the Bible that we should be able to document, yet our inability to do so — the absence of evidence — points to the non-existence of the Christian god. Further, this absence of evidence is everywhere. God doesn’t answer prayers, he doesn’t perform miracles, he doesn’t show any indication of caring about human actions, and moreover, even if he existed, he’d be morally bankrupt. In other words, we have no evidence of an omnipotent, omniscient, loving, and forgiving god. Given what we know of the world, such a god is impossible. So since there is no evidence where evidence would be expected, we can conclude that no such god exists.

While we can’t reach a definite conclusion about a deist god as easily, as we look in more and more places where we would expect to find evidence of some form of  creator, it’s not unreasonable to assume that one doesn’t exist. Yet this assumption isn’t proof.

As for an ignostic god? He’s merely an elusive idea that slips through our fingers and manages to escape both definitions and conclusions.  He’s beyond the comprehension of human intelligence, and so, I love him best.

  • Edward Clint

    Yes. A pet peeve of mine, and what will be a theme on my own blog, is widely-held misconceptions that get parroted about like trump cards.

    Absence of evidence for X IS evidence of absence when proposition X REQUIRES evidence to exist- which is actually quite often.

    Incidentally, I’m an atheist who will say we can know there is no god. “ignostic god” is oxymoronic of course. Deism just seems like game-playing at this point, but is nonetheless destroyed by philosophical inspection such as from ignosticism and metaphysics.

  • Copyleft

    I usually put it in terms of investigating UFO claims–after the 1,750th investigation turns up nothing, it’s pretty reasonable to ignore all the others and say “call me when you’ve got something new.”

  • James

    I’ve heard that, technically, only mathematicians can prove an hypothesis.

    To be certain of anything is rare (death and taxes; though the latter can be curbed significantly), but to be confident through evidence is very real, and quite a valid choice. Conversely, to reject a proposition, through the lack – or complete absence – of supportive evidence, may be fairly considered to be just as real and valid.

    Following a car, about to go through an intersection on a green light, I expect the car ahead to continue, justly, without slowing. I would not, and do not, expect that driver to stop suddenly. I do not cross that intersection *expecting* that car to stop. I am confident that the driver will continue, and they do.

    Just because the driver may stop, or may continue, does not give equal probability to both outcomes. In usual circumstances, I have no reason to expect the driver to do anything other than continue.

    Similarly, I have no reason, nor evidence, to think that a sentient creator exists, so I approach my life with that perspective.

    We don’t live our lives with certainty. We need little more than relative confidence to fumble from day to day; and though, as Hitchens expressed it, we “know more and more, about less and less”, what we do know, we can know with relative confidence. It doesn’t seem like an unrealistic, or unreasonable, choice to me.

    Kindly, James.

    P.S. I blame all typos, and poor analogies, on the late hour.

  • Bill

    Right, because the cosmogony of physicists attempting to explain the Big Bang doesn’t suffer from the same thing.

    I’m afraid it’s the nature of the beast. Once you get to what happened before the Beginning, it’s every man for himself. True, at one point the atheist and agnostic side of the argument could use “infinite regress” as a retort, but those days are gone. Science now is in the same boat. See:

  • Nicholas Covington

    You hit on the nail on the head blueharmony! Interestingly enough, what you’re saying can be proven logically and absolutely. With Bayes’ Theorem (which is itself logically proven), two or more theories are compared, and when a theory predicts the evidence better than another, that theory is judged more likely than it would have been otherwise (it is not necessarily the *most* likely, but better predictive power invariably makes a theory more likely than if it hadn’t made such good predictions).

    Here’s an example:
    Hypothesis 1: Aliens Exist
    Hypothesis 2: They Don’t
    Relevant Evidence: We have no evidence of aliens.

    The evidence is 100% likely if there are no aliens (they can’t land on earth if they don’t exist) but somewhat less than 100% likely if aliens do exist (if they existed, there’s at least a little bitty chance they might have landed by now). If you plug that in to any Bayesian calculator online, you’ll find that the final probability of the “no aliens theory” is at least a little bit higher than its prior probability (that it doesn’t imply that the “no aliens theory” wins the race or is even decidable, it just increases its likelihood, to a teency-tiny little degree at least).

    The probability will sink to the degree that a presence of evidence is predicted, so much so that in some cases an absence of evidence is conclusive.

    The more you know, lol. You get an ‘A’ in logic today! I think we’re gonna have fun blogging together.

  • aratina

    Congrats on getting onto the Skeptic Blogs network!

    As for this post, I don’t think your title went too far at all. It seems to me that absence of evidence is concrete evidence of absence in several ways.

    If, for instance, the thing that is absent has been looked for–repeatedly and in every currently imaginable way–leaving no detectable trace of its presence, then that ought to be conclusive evidence of its absence. Take the assertion that there is an elephant in your garage: that is easy to disprove by showing its absence. And gods have been searched for high and low in every imaginable way and have never been discovered. They are simply not there.

    Besides that, we KNOW where gods are–>in the brains of believers, which brings me to another way absence of evidence is evidence of absence: by having an alternative explanation for the absence that fits the evidence. If you used to have an elephant in your garage, but that elephant was rescued from you and put in a refuge, then one wouldn’t even need to look in your garage to know the elephant isn’t there. One could simply provide government documentation showing it was taken from your garage and put in the refuge, or one could trot down to the refuge and find it there. This is what science has done to gods and the supernatural. By showing how reality works, science has shown the alleged existence of those things to be mistaken beliefs. You don’t actually have to search for gods in a chemical reaction because people know to the best of our abilities how chemical reactions work.

    Anyway, that’s my thought on this matter. 🙂

    • Those are excellent points. I’ve long dismissed the realistic possibility of a theist god, and I’m quite certain that no deist god exists if only for the simple reason that we don’t even know what we’re looking for (nor would it matter). You can call any creating force a god, in that sense. Hence, ignosticism or even pandeism.

    • Achrachno

      I didn’t need to say what I said below. Aratina had already taken care of it, and I agree fully. Same general idea, different words.

  • Achrachno

    I’ve always taken “absence of evidence” in this context to mean “no one has looked yet”. If someone has looked, and nothing was seen, that’s evidence that nothing was there. Not conclusive, but evidence. If they looked and think they saw something, that’s evidence that something is there, subject to confirmation/test. “God” has the problem that millions have looked, but no one has ever come up with anything. There’s not an absence of evidence with respect to “God”, there’s considerable evidence that God is imaginary. Not conclusive, but about as good as we can expect.

    There are other problems with “God” but I’ll not bother with them, since you’ve already mentioned ignosticism and thus you’re obviously familiar with what I’d say.