this seems to contradict your previous claim. you didn't like that TAG was presented here as necessity and preferred a weaker plausibility approach. Now you are stating that TAG does actually strive to show it be the only possibility.

Okay? I wasn't stating a position on any of these matters. I do think that Frame is an important explicator of Van Til's theology, even if he disagrees with it himself in some matters.

It it not that important to me whether we frame TAG as a direct or indirect proof. Instead, what seems essential to me is that it have some premise like what you say here, "that things like logic, morality, and science can only make sense if they have their foundation in God." I've interpreted this as being equivalent to saying that if things like logic, morality, and science don't have their foundation in God, then they don't make sense (or if you prefer, if things like logic, morality, and science make sense, then they have their foundation in God.)

If I can show that logic, morality, and science do make sense on a non-theistic basis like Platonism, then this premise would be false. The point I've been stressing is that "making sense" is a weaker condition than being true. I don't have to show that Platonism is true to show this premise is false, but only that it "makes sense."

Many disagree that it's plausible the universe makes sense, Bertrand Russell for instance, or your friendly neighborhood existentialist.

The conclusion of the argument is absolutely valid, as are the conclusions of all logically valid deductive arguments. That isn't the same thing as modal necessity. The issue with valid deductive arguments is the truth of the premises. Given "The universe makes sense", one of the premises, then, with the other premises, if true, the conclusion is absolutely certain. This is not a claim of modal necessity which is what OrP seemed to be trying to refute. So TAG shows that, given the universe makes sense, the only possibility is that God exists. This isn't a bare assertion - the claim is supported by many discussions of the failure of any other proposed alternatives as well as why God's existence imparts rationality to the universe.

I don't agree with your claim. An existentialist may not think the universe makes sense, but that doesn't mean they deny even the possibility of an alternative.

to change wording, I find it hard to believe that anyone could reasonably proclaim that God cannot exist. They can claim that he doesnt exist, or probably doesn't exist - but 'cannot' - i don't believe there is any argument to show this (and possibly that there never could be).

and thats all it takes for plausibility, not showing that it cannot be.

failure to disprove is not proof.

The issue isn't whether Platonism makes sense but whether, given that it's true, do logic, etc., make sense. If, in some possible world, abstract logical rules are real objects, are they a sufficient foundation so that logic itself makes sense(is rational)? Van Til has an excellent discussion of Plato in which he shows why realism can't account for logic. One way he stated it in general was that if you place yourself, for argument's sake, on the position of the unbeliever and accept all his premises as true, does that account for rationality.

A word on abduction. If one surveys all the possible candidates for the foundation of rationality(in logic, morality, etc.), such as TAG, Plato, etc., it then becomes a question of which is the most plausible. Say, for instance, TAG is 51% and Plato is 49% - not the truth of the argument, but given its truth, what are the scope and explanatory power of the arguments, then abduction would say pick TAG.

Some people do effectively claim that the biblical God CAN'T exist. For instance, the classical Problem of Evil is often stated in such a way that, given evil in the world, a good god CAN'T exist, because omnipotence + goodness CAN'T allow evil to exist.

As to plausibility, see my last response to OrP.

I'm pretty confident Russell would not agree with the claim that the universe doesn't make sense without god. I am very confident that he would not have agreed with this claim about logic.

Here is the section you quoted, which shows that this is exactly what I said:

In philosophy of logic and maths, platonism refers to the view that there are actually existing abstract objects that are in some sense mind-independent (i.e. that do not exist solely as something being thought of by some mind.). The attraction of this view is that it gives us a relatively clear way of saying how it is that foundational logical or mathematical claims are true--they are true in a way roughly analogous to how claims about physical objects are true. If you accept a correspondence theory of truth, this means that they are true if in some way the claims about logic correspond to reality, i.e. accurately describe the properties of the abstract objects of logic/math.

So, if this theory is true, then logical claims make sense (they refer to the abstract logical objects) and have a truth-value. Now, let's take Van Til's thought experiment here and place ourselves in the position of the unbeliever that accepts platonism and ask whether that accounts for logic. Well, since his platonism gives an account of the meaning and truth of logical claims (the account I gave above), it certainly makes sense. So where is the argument that a non-theistic platonism cannot account for logic?

Just as a general note, rather than just telling me that Van Til has an excellent discussion of Platonism, just tell me his criticism of Plato. Having an excellent discussion of Plato doesn't make Van Til very unique--probably no one in philosophy has been as discussed. I'm more interested in how he actually shows that Platonism doesn't work to justify logic even if true.

TAG is not an abductive argument. I already explained this in my prior post. If TAG is sound, then the probability that platonism explains logic is 0%.

Look, you clearly have an argument in mind here. You think that God provides the best explanation for the intelligibility of the world, morality, and so on. Fine. There is an argument to be made for that conclusion. But, TAG is not it.

So here is the moral argument as presented by W.L. Craig:

1. If God does not exist, objective moral values and duties do not exist.

2. Objective moral values and duties do exist.

3. Therefore, God exists.

This is a TAG style argument. But it is not an inference to the best explanation--it states absolutely that if God doesn't exist, then objective moral values and duties also do not exist. It is not saying that there are a menu of of options for explaining objective moral values and duties and the theistic one is the best (note that in this article Craig explicitly contrasts his formulation of the moral argument with another version of the moral argument formulated as an inference to the best explanation.).

It is Craig's version of the moral argument that I find so objectionable (and the TAG-style arguments). I think the abductive versions, such as some of the arguments here, much more reasonable and worth discussing.

http://www.philosophicalsociety.com/...%20worship.htm

No doubt you can find language from Russell about purpose and meaning. So with Nietzsche, Sartre, etc. This only confirms Van Til's thesis that atheism requires both absolute rationalism and absolute irrationalism.

I didn't say it is. It can be put into deductive form or transcendental form. Abduction is the method of deciding which of several possibilities ought to be accepted.

Russell believed that the universe didn't have a purpose. That doesn't mean he believed that it didn't make sense. Rather, he believed that teleological explanations of the universe were not part of true science.

There isn't a "transcendental logical form." It's true that transcendental arguments are usually indirect proofs, but not all indirect proofs are transcendental and, as per John Frame, you can put a TAG argument into a direct proof form.

Instead, TAG refers to a kind of argument where you argue that "things like logic, morality, and science can only make sense if they have their foundation in God" i.e. where you claim that God is a pre-condition of logic, morality, or science.