Thoughts on the “Logical vs. Evidential” Distinction

Chris Hallquist recently questioned the significance of the distinction between logical arguments from evil and evidential arguments from evil. He writes:

In general, the insistence of people who follow these issues on classifying versions of the problem of evil as either “logical” or “evidential” is weird. It isn’t something you see with any other kind of argument in philosophy. What we care about with deductive arguments is first whether they are valid, and second whether the premises are true, whether people can agree that they’re true, whether people should agree that they’re true, etc.

If there’s agreement that an argument is deductively valid and the premises are true, it doesn’t matter if the premises are logical truths, if they’re necessary or contingent, or if they’re a priori or a posteriori. It matters somewhat whether we’re certain the premises are true, or whether we just think they’re just probably true, but thinking an argument’s premises are only probably true doesn’t turn the argument into an “evidential” or “probabilistic” argument.

I think Hallquist is right. In fact, even within the philosophy of religion we don’t find, say, theistic arguments classified as “logical” or “evidential.” (For example, have you ever seen someone refer to the ‘logical’ version of the kalam cosmological argument, as opposed to its ‘evidential’ version?)

Furthermore, Hallquist is not the first person to question the significance of the distinction. Daniel Howard-Snyder, in his introduction to his anthology, The Evidential Argument from Evil, wrote this.

While we may easily draw this distinction [between logical and evidential arguments from evil], we are hard pressed to defend its significance. I’m afraid I don’t have much to say about the matter, except for the obvious. I mean, whenever one meets what its author purports to be an argument from evil (in contrast with, say, the sort of response to horrendous evil that you might find in Albert Camus’s The Plague or Eli Wiesel’s Night), one ought to consider whether the author intends to assert that facts about evil known with certainty are incompatible with theism. If she does, then one should query why the argument is not dubious for the same reason that Mackie’s argument from evil is dubious. If she does not–that is, if she intends to say that facts about evil which are known with certainty make theism significantly unlikely, or that theism is incompatible with certain facts about evil that are themselves quite likely–then one needs to think hard about the sorts of issues this book is about. (p. xvi)

Independent of whether the logical vs. evidential distinction is significant, I have a problem with it from a ‘naming convention’ perspective. Logic is commonly divided into two branches: inductive and deductive. Based on that, what is a student supposed to think when an author refers to a “logical” argument from evil? Are they supposed to  say, “Oh, so your argument is, like, really logical?” And if “logical arguments from evil” are, well, logical, then does that mean that “evidential arguments from evil” are illogical?!?

I think a less confusing set of labels are “logical incompatibility arguments” and “comparative improbability” arguments. According to arguments of the first type, some fact about evil is–you guessed it–logically incompatible with theism. Arguments of the second type claim that some fact about evil, while logically compatible with theism, is less probable on theism than it is on naturalism. These proposed alternative labels are not as concise as the “standard” terminology, but at least it’s clear what they mean!

I personally find the distinction marginally useful insofar as categorizing arguments for or against God’s existence this way makes it very convenient to identify what type of defeater is required to refute such arguments.

About Jeffery Jay Lowder

Jeffery Jay Lowder is President Emeritus of Internet Infidels, Inc., which he co-founded in 1995. He is also co-editor of the book, The Empty Tomb: Jesus Beyond the Grave.

  • http://twitter.com/UncredibleHallq Chris Hallquist

    I think a less confusing set of labels are “logical incompatibility arguments” and “comparative improbability” arguments. According to arguments of the first type, some fact about evil is–you guessed it–logically incompatible with theism. Arguments of the second type claim that some fact about evil, while logically compatible with theism, isless probable on theism than it is on naturalism. These proposed alternative labels are not as concise as the “standard” terminology, but at least it’s clear what they mean!

    This still seems worrisome, for reasons similar to the ones I gave in the paragraphs you quote. This categorization may not be exhaustive, depending on your theories of what makes a necessary truth and things like that. Mackie originally called the premises of his argument “quasi logical truths,” might that be a bigger category than logical truths simpliciter? What about conceptual truths? Might there be metaphysically necessary truths that aren’t logical truths.

    Or, we may be inclined to assert, “God, if he existed, wouldn’t have allowed X to happen” without even thinking it’s a necessary truth. Rather, we might be thinking something like, “We have strong moral intuitions that God, if he existed, would not have allowed X to happen given all the relevant facts that as far as we can tell obtain, which may be difficult to exhaustively specify.” Something like that–that’s just my first stab at how you might spell out some intuitions a lot of people seem to have.

    ETA: I guess the relevant premise would be something like a counterfactual, except with disagreement about whether the antecedent is true. The key point being that counterfactuals can be true without applying across all possible worlds. Analyzing the relevant premises exactly would be hard, for the same reasons analyzing counterfactuals is hard.

  • Bradley Bowen

    Chris Hallquist said:

    If there’s agreement that an argument is deductively valid and the premises are true, it doesn’t matter if the premises are logical truths, if they’re necessary or contingent, or if they’re a priori or a posteriori.

    =================

    Doesn’t matter for what purpose?

    It seems to obviously matter whether a premise is a priori or a posteriori, because we have different ways of evaluating claims that are a priori than for claims that are a posteriori. It seems obiously to matter whether a premise is a logical truth or not. We have specific ways of evaluating alleged logical truths that don’t apply to other sorts of truths.

    Classifying what sort of claim a premise makes seems like a basic requirement for being clear about the meaning of the claim and for being clear about how one should go about investigating or evaluating the truth of the claim. If so, then making such classifications seems to be of obvious significance.

  • Bradley Bowen

    Jeff Lowder said:

    I think Hallquist is right. In fact, even within the philosophy of religion we don’t find, say, theistic arguments classified as “logical” or “evidential.” (For example, have you ever seen someone refer to the ‘logical’ version of the kalam cosmological argument, as opposed to its ‘evidential’ version?)

    ===========================
    OK. But arguments for the existence of God are traditionally divided up into a priori vs a posteriori arguments, which seems to be making the same sort of distinction.

    I suppose you could say that the premise ‘Evil exists’ is a posteriori, not a priori, not a necessary truth. But the logical problem of evil could be stated so that it proves a conditional statement: If evil exists, then there is no God. Such a conditional statement could be defended as being a necessary truth that is based purely upon consideration of the meanings of the words “God” and “evil”, having no basis in empirical evidence.

    Such an argument would be a priori rather than a posteriori, and I don’t see it as being unreasonable to call such an argument ‘the logical problem of evil’ indicating that the argument does not require any empirical facts or evidence.

  • Lenoxus

    There’s no “logical” kalam cosmological argument because few people are interesting in proving that “God exists” is a logical possibility. The logical possibility of God is assumed a priori thanks to a religious background of the cultures having these philosophical discussions. Hence, the kalam cosmological argument is “evidential” instead.


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