September 29, 2010

Evolution and Teleological Arguments

Much of Sobel's chapter on teleological (design) arguments is devoted to Hume interpretation and to explaining Bayesianism. The latter seems to be one of several places where Sobel has not decided whether he is writing a textbook or a monograph. As for the former, the 'analogical' version of the teleological argument is, I think, not the strongest version and, although I haven't conducted a survey of the various treatments, I would be surprised if Hume's version turned out to be the best. After all, Hume is at most a half-hearted supporter of the argument; even he doesn't think his argument...
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September 28, 2010

Explanatory Principles and Infinite Propositions

In the course of his discussion of cosmological arguments, Sobel argues against the Principle of Sufficient Reason and similar strong explanatory principles. In particular, he argues that even a weak principle like "there is a deductive explanation that has only true premises for every contingent truth" will result in modal collapse (p. 218). In Sobel's terminology, an argument 'deductively explains' its conclusion iff (1) the argument is sound, and (2) the conclusion does not entail the premises (p. 219; condition (2) applies to contingent conclusions only). Sobel now introduces the following two premises: (3) If there is any true contingent...
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September 27, 2010

Joining the Prosblogion

I am pleased to announce that I have been invited to join The Prosblogion, the premier philosophy of religion blog! As the invite seems to have resulted largely from my series on Sobel's Logic and Theism, I suppose that, in addition to thanking the Prosblogion folks for inviting me, I should thank Jonathan for challenging me to engage seriously with an atheist writer on my blog, and Brandon for suggesting Logic and Theism as the text of choice. From now on, any serious, contentful posts on philosophy of religion (including the remainder of the Sobel series) will appear both here...
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September 23, 2010

A Non-Leibnizian Cosmological Argument

In my last Sobel post, I reconstructed the cosmological argument Sobel attributes to Leibniz in such a way that there was no obvious contradiction in the premises by using Leibniz's own resources. Here I want to try to produce an argument with more widely accepted premises. Recall that Sobel's reconstruction is as follows: (1)The World - the Cosmos - exists. (2) The World is contingent, it is a contingent entity. (3) For everything that exists - for every fact and every existent entity - there is a sufficient reason for its existence. (4) The sufficient reason for the existence of...
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September 21, 2010

"Leibnizian Miracles" in Pomona

I have just officially accepted an invitation to present "A Leibnizian Theory of Miracles" at the Southern California Philosophy Conference, to be held in Pomona Saturday, November 6.
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September 20, 2010

September 15, 2010

A Leibnizian Cosmological Argument

Sobel's sixth chapter is devoted to, as he says, "proofs a contingentia mundi" (from the contingency of the world). The chief exponent here is Leibniz, though Sobel also considers Hume's Demea and his probable source, Samuel Clarke. Sobel argues that Leibniz's argument is valid ... by contradiction explosion. That is, he argues that Leibniz's premises are inconsistent. In this post, I show how to fix the argument using Leibnizian resources. In the next post, I will give another version of the argument which uses premises which I consider to be anti-Leibnizian, but which I think are more widely held than...
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September 13, 2010

What is Supposed to be Proved in Aquinas's Five Ways?

I'm not a Medieval scholar, so I don't really know what I'm talking about, but that's ok. Sobel's fifth chapter is concerned with Aquinas's Second Way, one of the classic texts for the cosmological argument. Sobel raises some concerns about the premises, but for the most part he finds them plausible (though he may ultimately reject one or more of them). His main concern is that, as he schematizes the argument, a fallacy of equivocation occurs at the very end. Sobel reads the 'good' part of the argument as (perhaps) justifying the 'Preliminary Conclusion'...
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September 7, 2010

Would a Being With All Positive Properties Be God?

Sobel's final objection to ontological arguments is that, even if they are sound, their conclusion does not mean that God exists. That is, according to Sobel, a necessarily existing 'being than which none greater can be conceived' or 'being with all perfections' or 'being with all positive properties' would not be God. His argument for this is rather confusing and depends (1) on a controversial modal intuition, and (2) on an odd definition of 'worshipfulness'. As far as I can tell, the argument goes like this: it is clear (so Sobel claims) that such properties as consciousness, knowledge, power, love,...
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September 2, 2010

Modal Collapse: Sobel's Objection to Gödel's Ontological Argument

The last ontological argument Sobel discusses is the Leibniz-inspired argument put forward by the famous logician Kurt Gödel. Gödel sets up a formal system in third-order quantified modal logic with equality and abstraction (!) and proves within that system the theorem: □∃xG(x) Where the predicate G is defined as follows: Gx ↔ ∀φ[P(φ) → φ(x)] Where P is primitive. (Sobel includes the complete source texts for Gödel's proof on pp. 144-146.) Now, unsurprisingly, given that the proof was originated by Gödel, everyone agrees that the proof is valid in the formal system. The question is whether there are any interpretations...
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