Friday, December 28, 2007

An Excellent Encyclopedia Entry on the Evidential Argument From Evil

...can be found here. The author is Nick Trakakis. Nick is a hot up-and-comer in philosophy of religion. He recently published a monograph with Ashgate Press on Rowe's evidential argument from evil, which displays a command of all the literature on the argument. He has also published a slew of journal articles on it, in which he makes a genuine contribution to the debate. He is therefore an ideal person to learn from on this topic.

Thursday, December 20, 2007

Philosophical Gerrymandering and Cumulative Case Arguments For Theism

I've argued that no argument for God, taken by itself, demonstrates theism -- or even makes theism more probable than not. However, this leaves open the possibility that, when taken together, these arguments do demonstrate the truth of theism, or at least make theism more probable than not.

Richard Swinburne is one famous philosopher of religion who takes this approach to arguments for theism[1]. He uses a formula from probability calculus known as Bayes' Theorem to argue in this way. He calls an argument that raises the probability of a hypothesis a good C-inductive argument, and he calls an argument that makes a hypothesis more probable than not a good P-inductive argument. He then considers a large variety of arguments for theism, and admits that none of them, when construed as a deductive argument, constitutes a sound argument for God's existence. However, he argues that a number of them, when reformulated as inductive arguments, each raise the probability of theism at least a little bit. Thus, he thinks that a number of them are good C-inductive arguments for theism. And when taken together, they make theism at least a little bit more probable than not, making the set of arguments taken together a good P-inductive argument for theism.[2]

To illustrate Swinburne's ideas about C-inductive arguments, P-inductive arguments, and cumulative case arguments, consider a simpler example. Suppose we're detectives investigating a murder, and that we know that either Smith committed the murder or that Jones did it. Then we have two hypotheses:

H1: Smith committed the murder
H2: Jones committed the murder

Suppose further that the following constitutes all our evidence, or data:

D1: Smith's fingerprints are on the murder weapon (a gun)
D2: Jones's fingerprints are on the murder weapon
D3: Smith had a strong grudge against the victim for sleeping with his wife
D4: Jones disliked the victim
D5: Jones is a terrible shot
D6: A somewhat reliable acquaintance of Jones said they talked to Jones at his house at 8pm, which was only 10 minutes before the time of the murder.
D7: Jones lives about 15 minutes from the victim's house.
D8: Smith lives 5 minutes away from the victim's house.

Notice that no single piece of evidence makes either hypothesis even slightly more probable than not -- i.e., not one of D1-D8, when considered individually, is a good P-inductive argument for either hypothesis as to who killed the victim. However, each one (or at least most of them), when taken individually, raises the probability of the relevant hypothesis at least a little bit, in which case each one (or at least most of each one) is a good C-inductive argument. And when taken together, they do make H1 a bit more probable than H2. In fact, D1-D8, taken together, constitutes a good P-inductive argument for H1. Similarly, even if none of the arguments for God establish the truth or the probability of theism, perhaps they do when taken together. Well, do they?

I've already mentioned that Swinburne thinks they do. Some other examples include J.P., Moreland[3], WIlliam Lane Craig, and Basil MItchell.

So, for example, suppose our hypotheses are:

H1: theism
H2: naturalism

And suppose our data are:

D1: the apparent contingency of the universe
D2: the apparent fine-tuning of the universe
D3: the apparent irreducibility of consciousness to the physical
D4: religious experiences of various sorts
D5: the existence of morality[4]

What's the probability of H1 on D1-D5? Of course, as everyone in this debate admits, there's probably no way to assign precise numerical values to the pieces of evidence here, whether taken individually or collectively[5]. To be charitable, though, let's say that each of D1-D5 raises the probability of theism at least a bit, and thus each is a good C-inductive argument for theism. Furthermore, let's be charitable and say that, when taken together, the probability of H1 on D1-D5 is a very strong P-inductive argument, raising the probability of H1 to .9 (i.e. 90%)[6]. Do we now have a cumulative case argument based on D1-D5 that makes the posterior probability of H1 higher than that of H2?

No, we don't. For to truly assess the posterior probability of a hypothesis, one has to include in the data pool *all* of the evidence that has a bearing on the hypotheses in question; to ignore the other evidence is tantamount to philosophical gerrymandering: artificially limiting the range of relevant evidence in order to ensure the conclusion you want. It would be analogous to arguing above that Jones probably committed the murder by just presenting D2, D4, and D6 of the data presented there, and suppressing all the rest.

But it turns out that there is a lot of data that appears to conflict with theism that needs to be added to the data pool before we can properly assess the hypotheses. Some of this evidence includes:

D6: massive amounts of apparently random and pointless suffering
D7: massive religious diversity
D8: empirical studies on the ineffectiveness of prayer
D9: the apparent hiddenness of God
D10: evolution

But once we throw in this data, it's no longer clear whether H1 (i.e., theism) is more probable than H2 (i.e., naturalism): even if the probability of H1 was about .9 on D1-D5, it sinks down to about .5 (i.e., 50%) when we evaluate it on D1-D10. At worst, H1 is lower than .5 on the total evidence.

So it seems to me that cumulative case arguments for theism fare no better than the same arguments taken singly.

1. See especially his classic book, The Existence of God (Oxford: Clarendon Press, 1979). In this post, I refer to the revised edition (1991). An extensively revised edition was released in 2004. A popular-level presentation of the main ideas in that book can be found in his book, Is there a God? (Oxford: OUP, 1996).

2. While this is roughly correct, technically it isn't quite right. In at least the original edition, Swinburne argues for the weaker claim that, taken together, the arguments for theism he endorses give theism a probability of at least .5 (50%), or thereabouts. He then argues that (what he dubs) the Principle of Credulity applies to religious experience -- i.e., like ordinary perceptual and memory experience, religious experience enjoys prima facie justification (it's "innocent until proven guilty"). But since he thinks he's shown that theism isn't improbable on the evidence (i.e., it's not less than 50% probable), then the prima facie justification of religious experience isn't undercut, and thus religious experience of God justifies theism. In an appendix in the 1991 version of the book, he considers the new "fine-tuning" version of the design argument, and concludes that with this new piece of data, theism is indeed more probable than not, in which case there is a decent P-inductive, cumulative case argument for theism. I haven't read the newest edition of Swinburne's book, but I believe he is even more optimistic about the cumulative case for theism is if anything even stronger than he thought in his 1991 version.

3. Moreland's views here are a bit more optimistic than Swinburne's. He thinks that there are a lot of sound deductive arguments for theism, and that several versions of the design argument are good P-inductive arguments all by themselves. Thus, the function of a cumulative case for theism isn't primarily to make theism more probable than not, but rather to (i) provide a finer-grained conception of the identity of the God established by the arguments (e.g., to rule out deism), and (ii) to strengthen a theistic case already made strong by most of the arguments taken by themselves. See his "rope" analogy of theistic arguments in his debate with Kai Neilsen (Does God Exist? The Great Debate), as well as his remarks in Philosophical Foundations for a Christian Worldview (co-authored with William Lane Craig). William Lane Craig seems to endorse this view as well. This comes out especially in his discussion of the arguments of natural theology in his popular-level debates, as well as the co-edited book on the Christian Worldview just mentioned.

4. It should be pointed out that although at least some theists take moral arguments to support theism, Swinburne does not -- indeed, he doesn't even think they make good C-inductive arguments for theism. For he takes moral truths to be necessary truths, akin to mathematical truths (e.g., 1+1=2), in which case they would exist even if God did not. See his discussion of this in his chapter on moral arguments in his The Existence of God (1991).

5. For example, Swinburne says this explicitly in the final chapter (not the appendix) of The Existence of God (1991). Plantinga says this in Warranted Christian Belief (Oxford: OUP, 2000).

6. This is of course extremely generous. For not even Swinburne thinks the probability is this high even when you add more theism-friendly pieces of data (see footnote 2, where I mention that Swinburne thinks the data give theism a posterior probability of around .5). Plantinga more-or-less agrees with Swinburne's assessment. See Plantinga's section on the Problem of Dwindling Probabilities in Warranted Christian Belief, where he argues that inductive arguments for theism aren't sufficiently strong to render religious belief epistemically appropriate.

Wednesday, December 19, 2007

Online Course on the Old Testament

This looks to be a great course on the Old Testament at Yale. It comes complete with a syllabus and lectures in both audio and video formats. I imagine it's worth browsing around there to find other classes in various disciplines. Isn't it great to know that you can now sit in on courses at Ivy League universities at home in your pajamas, and at no monetary cost to yourself?

Thursday, December 13, 2007

The Trouble With Plantinga's Reformed Epistemology In A Nutshell (Draft)

Plantinga rightly points out that classical foundationalist accounts of properly basic beliefs are inadequate -- not enough beliefs count as properly basic. Unfortunately, Plantinga goes too far -- too many beliefs count as properly basic on his account. He wants to widen the circle of properly basic beliefs so as to allow belief in God to count as properly basic, but he can't do so in a way that's plausible.

To see this, recall the inductive procedure Plantinga recommends for generating criteria of proper basicality: a person considers actual and hypothetical circumstances in which a belief of a certain type is formed. In each considered circumstance, the person asks herself whether the belief is rational (i.e., properly basic or properly based) or irrational (i.e., improperly basic or improperly based). If that type of belief is judged to be neither irrational nor rational-but-properly-based, then the belief is judged to be properly basic (at least if it is judged to be so in enough actual and/or hypothetical circumstances).

But at this point, a worry arises: whose judgements do we include with respect to this process of determining which beliefs are properly basic? This worry gives rise to the following dilemma: Either the Christian community limits its group of judgers to, well, the Christian community, or they allow others to judge. If they choose the former, then the worry is that this is arbitrary: there seems to be no principled way to say that other communities can't play the same game. So, for example, suppose atheists choose to limit their judgers to those within the atheist community. Suppose further that, when they go through this process of judging which beliefs are properly basic, they come to judge theistic belief to be something other than properly basic. Then by parity of reasoning, we should say that the atheists are just as much in their epistemic rights in saying that belief in God is not properly basic for them as Christians are in saying that it is properly basic for them. The same goes for every other community -- Muslims, Mormons, primitive island tribes, etc. This entails a radical form of relativism about rationality -- one which many Christians and non-christians will see as unpalatable and implausible (e.g., do Christians really want to say that atheists are reasonable and blameless in their denial of God's existence? Do people, whether Christian or not, want to say that what counts as rational is relative from community to community?).

On the other hand, if they allow other judgers to judge which beliefs are properly basic, then the worry is that belief in God probably won't be judged to be properly basic. In fact, a number of Christian philosophers (e.g., James Sennett) and atheist philosophers (e.g., Keith Parsons) argue that the least arbitrary criteria for proper basicality include the following two: (i) the belief is universally held, and (ii) the belief is such that a recognizable human life is impossible without it. So, for example, belief that there are material objects, that there are other minds besides our own, that there is a past, that memory is reliable, etc., meet these criteria; they are therefore plausibly construed as properly basic beliefs. But on this account, belief in God is not properly basic, since belief in God is neither universally held nor necessary for a recognizable human life.

In short, we have no good reason to think that belief in God is properly basic, and we have good reason to think that it isn't. For we either allow only Christians to judge which beliefs are properly basic or we don't. If we do, then we get an implausible version of relativism about rationality. But if we don't, then belief in God probably won't be judged to be properly basic.

This is a rough paraphrase of an objection raised by a number of philosophers. James Sennett is an example of a Christian philosopher who raises this sort of objection (see his book, Modality, Probability, and Rationality: A Critical Examination of Alvin Plantinga's Philosophy). Keith Parsons is an example of an atheist philosopher who raises this sort of objection (see his essay in the philosophy of religion textbook, God Matters).

I'll get around to replies to this objection based on Plantinga's recent externalist construal of proper basicality in a later draft of this post.
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