Midas Vuik

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I have examined both the Leibnizian and Thomistic Cosmological Arguments, but how are they really different? WLC seems to be making a distinction between them that is rather vague. Could anyone here explain it in further detail?

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hamlet

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Difference between Leibnizian and Thomistic Cosmological Arguments
« Reply #1 on: January 04, 2010, 09:30:15 pm »
They are similar, but I do think there is a distinction there.  The Thomist and Leibnizian arguments are both cosmological arguments based on contingency, whereas what Craig calls the kalam cosmological argument is based on temporal becoming. That distinguishes Aquinas and Leibniz's arguments from the kalam argument.

The Thomist and Lebnizian arguments are distinguished by the fact that Thomas's argument involves his whole Aristotelian metaphysic, while Lebniz's argument doesn't. Leibniz's argument just involves his principle of sufficient reason. What Thomas added to Aristotle's metaphysic is really interesting. What Aristotle missed, according to Aquinas, is existence. If you know a little Aristotle, you know that he talked about form and matter (hylomorphism). He said that whatever exists has some form or other (and this form makes it what it is) and made no further question about existence. Aquinas noticed that the form of a thing (its "whatness") can be thought of without thinking that the thing exists. For example, you can think of horsiness without thinking of an actually existing horse. Form doesn't guarantee existence. Existence is something added to form. That's what Aquinas thinks Aristotle missed. It follows that everything is contingent. That is, unless there is some being whose essence (or form) just is existence. And that's exactly how Aquinas wants to argue for the existence of God.

Leibniz skips the Thomistic metaphysic and says there must be a sufficient reason why anything is so and not otherwise. The difference between the arguments is the difference between the PSR and the Thomistic metaphysic. But as far as why Leibniz thinks everything (except God) is contingent, I think it stems from his idea that in every true statement the predicate is contained in the subject. But I can't explain it any further. Check the following link out. http://plato.stanford.edu/entries/leibniz/#PreNotPri


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SnoopDoug

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Difference between Leibnizian and Thomistic Cosmological Arguments
« Reply #2 on: January 31, 2010, 10:19:07 pm »
The Thomistic version (TCA) posits that there must be a First Cause that exists as the source of all dependent things.  The Leibnizian version (LCA) is compatible with this, but goes further by stating that a logically necessary being exists that explains all logically contingent things.

Notice that the TCA, at least prima facie, allows for the existence of brute facts.  Richard Swinburne's defense of the cosmological argument is basically an inductive form of the TCA.  There are different starting principles utilized in each argument:

TCA: "Every existing thing is either dependent or independent."

LCA: "Every existing thing is either contingent or necessary."

A thing can be both dependent and necessary, however.  What the TCA refers to is a thing's metaphysical contingency (i.e. "dependency"), whereas the LCA refers to a thing's logical contingency.
"Preach the Gospel at all times; and if necessary, use words." -St. Francis of Assisi

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SnoopDoug

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Difference between Leibnizian and Thomistic Cosmological Arguments
« Reply #3 on: February 01, 2010, 11:21:53 pm »
I forgot to add that the conclusion of the TCA is distinct from the conclusion of the LCA.  Thomas' First Cause exists by a metaphysical necessity, but not necessarily a logical necessity (existing in all possible worlds).  The LCA, on the other hand, concludes precisely that a logically necessary being exists.

It's also worth mentioning that while the TCA does not necessarily result in a logically necessary First Cause, there is nothing in the argument that opposes such a conclusion.

"Preach the Gospel at all times; and if necessary, use words." -St. Francis of Assisi