An Irrefutable Ontological Argument?

Mike Almeida has presented an ingenious new probabilistic version of the ontological argument at Prosblogion. As I understand it, the basic idea is this. Consider the following properties:

Goodness
Power
Knowledge
Being concrete (as opposed to being abstract)
Necessary existence

Mike's argument seems to be this. The first three properties admit of an infinite number of degrees. Furthermore, at least very many combinations of these degreed properties are compossible -- perhaps infinitely many. Furthermore, these combinations are compatible with the fourth property of being concrete. So there seem to be an infinite number of compossible combinations of the first four properties:

Goodness
Power
Knowledge
Being Concrete

Therefore, given the infinite number of possible combinations of these properties, it's highly probable that at least one such combination is compatible with the fifth property mentioned earlier, viz., the property of necessary existence. Therefore, since every set of compatible properties is possible, it's highly probable that a necessarily existent concrete individual with some degree of goodness, power, and knowledge is possible. And since (by Axiom S5 of S5 modal logic) whatever is possibly necessary is necessary simpliciter, it's highly probable that a necessary being with some degree of goodness, power, and knowledge exists.

In the comments of the post, Yujin Nagasawa raises the worry that the argument proves too much: if it really is true that at least one combination of the first four properties is compatible with necessary existence, then it also seems highly probable that other combinations of the properties are compatible with necessary existence as well. But if so, then the argument would seem to show that multiple necessary beings of this sort exist.

My own view is that our knowledge of what's metaphysically possible is quite limited, and thus that the probability of the compossibility of the first four properties with necessary existence is inscrutable. The basic idea is that while some properties are intrinsically compatible with other properties (e.g., the property of being a cat is compatible with the property of being white), some are not (e.g., the property of being a prime number is incompatible with the property of being a prime minister, to borrow an example from Plantinga). But if two or more properties are intrinsically incompatible with one another, then the fact that such properties come in degrees -- even infinitely many degrees -- is irrelevant to whether they can fit together coherently: if the properties involved are intrinsically incompatible, then not one of those combinations is possible. And the problem is that we don't know whether the properties involved in the argument are compatible (i.e., we don't know whether they are more like those involved in being a cat and being white, or more like those involved in being a prime number and being a prime minister).

Plantinga's "Reason and Belief in God"...

...is now online at his department webpage at Notre Dame, here. (thanks, Al!). This 1983 text is the most developed exposition and defense of Plantinga's earlier internalist account of properly basic belief in God. It's still considered a classic. If you're interested in understanding and evaluating Plantinga's reformed epistemology, this is the place to start.

Salerno and Brogaard's Critique of the Argument from Anti-Realism to Theism

In his 1982 APA presidential address, "How to be an Anti-Realist", Alvin Plantinga (Notre Dame) argued that anti-realism is true, and that the best account of anti-realism entails the truth of theism. Plantinga summarizes his argument at the end of his address as follows:

"By way of conclusion then: the fundamental anti-realist intuition-
that truth is not independent of mind--is indeed correct. This intuition
is best accommodated by the theistic claim that necessarily, proposi-
tions have two properties essentially: being conceived by God and being
true if and only if believed by God. So how can we sensibly be anti-
realists? Easily enough: by being theists."

Recently, Michael Rea (Notre Dame) has offered a similar version of Plantinga's argument (‘‘Theism and Epistemic Truth-Equivalences’’, Nous 34:2 (2000), pp. 291–301).

Joe Salerno (Saint Louis University) and Berit Brogaard (U of MIssouri, St. Louis) published a paper ("Anti-realism, Theism and the Conditional Fallacy", Nous 39:1 (2005), pp. 123-139) that critiques Plantinga's and Rea's versions of the argument. The paper can be found here.

Review of Swinburne's 2nd Edition of The Existence of God

Richard Swinburne's The Existence of God (Oxford: Clarendon Press, 1979) is widely considered a high point in the defense of classical theism. There, he reformulated the classical arguments for theism as inductive arguments, using the machinery of Bayes' Theorem. He came out with a second edition of the book in 2004. A helpful review of the new edition can be found at Notre Dame Philosophical Reviews, here.

Paul Draper's 2009 SPR Presidential Address

In his 2009 presidential address to the Society for Philosophy of Religion, Draper presents a paper arguing that theists bear a heavy burden of proof. His argument is based on an application of his new theory of intrinsic probability for the probability calculus. First, he briefly explains his theory of intrinsic probability, and why it's superior to Richard Swinburne's. He then applies his theory by showing resultant problems for generating good Bayesian arguments for theism. The audio of Draper's address can be found here.

Welcome to the cutting edge, kiddies.

Deane-Peter Baker's Recent Book, Alvin Plantinga

If you're evaluating Plantinga's work in philosophy of religion, get this book:

Baker, Deane-Peter. Alvin Plantinga (Cambridge UP, 2007).

Here's the blurb from the Cambridge UP website:

"Few thinkers have had as much impact on contemporary philosophy as has Alvin Plantinga. The work of this quintessential analytic philosopher has in many respects set the tone for the debate in the fields of modal metaphysics and epistemology and he is arguably the most important philosopher of religion of our time. In this volume, a distinguished team of today’s leading philosophers address the central aspects of Plantinga’s philosophy - his views on natural theology; his responses to the problem of evil; his contributions to the field of modal metaphysics; the controversial evolutionary argument against naturalism; his model of epistemic warrant and his view of epistemic defeat; and his recent work on mind-body dualism. Also included is an appendix containing Plantinga’s often referred to, but previously unpublished, lecture notes entitled 'Two Dozen (or so) Theistic Arguments', with a substantial preface to the appendix written by Plantinga specifically for this volume."

And here's the table of contents:

Introduction: Alvin Plantinga, God’s philosopher - Deane-Peter Baker
1. Natural theology - Graham Oppy
2. Evil and Alvin Plantinga - Richard M. Gale
3. The modal metaphysics of Alvin Plantinga - John Divers
4. Natural theology and naturalist atheology: Plantinga’s evolutionary argument against naturalism - Ernest Sosa
5. Two approaches to epistemic defeat - Jonathan Kvanvig
6. Plantinga’s model of warranted Christian belief - James Beilby
7. Pluralism and proper function - Kelly James Clark
8. Plantinga’s replacement argument - Peter Van Inwagen
Appendix: Two Dozen (or so) Theistic Arguments - Alvin Plantinga.

Btw: the editor of the collection (Deane-Peter Baker) is a Christian philosopher who recently wrote a very helpful article on Plantinga's externalist account of warranted Christian belief ("Plantinga’s Reformed Epistemology: What’s the Question?", International Journal for Philosophy of Religion 57:2 (2005), pp. 77–103). After explicating Plantinga's account, he evaluates it by analyzing a virtually comprehensive list of criticisms of his account to date. He argues that the criticisms with real force reduce to four -- what he dubs (i) the proper basicality challenge, (ii) the ethical objection, (iii) the ‘further question’ objection, and (iv) the problem of religious diversity. He concludes that these criticisms have sufficient force to show that, pace Plantinga, positive arguments for Christian belief are required.

I've Re-Converted to Christianity

And once you look at the calendar, you'll have an undercutting defeater for that belief. ;-)

Alimi's New Paper on the Problem of Divine Domination

Alimi, Toni. Divine domination . Religious Studies (2025), 1–19. doi:10.1017/S0034412525100917 Abstract: This article develops the problem ...