Tomislav Ostojich wrote:

Listen to the central claim of modal concordism: possible worlds actually exist. But then they're not merely possible world's anymore.

I like this argument.

David Lewis would draw a distinction between existence and actuality. He would say that every possible world exists, but that for someone to say a world is actual is just for them to say they're in that world. In other words, he would say actuality is indexical.

Greg wrote:

God's knowledge that w is the actual world is a Cambridge property of him, as would be his knowledge that v is the actual world if v were the actual world. Thus the possibility of God possessing knowledge that v is the actual world does not imply mutability.

But surely whether God knows that w is the actual world or that v is the actual world is a real difference?

The concern if so, I think, is that this response makes it so that God never really knows whether w or v is the actual world. (If God's knowing that w or v is actual are Cambridge properties, there's no difference in him no matter what world is actual.) He has knowledge of all possible worlds and what would happen in them if actual, but no additional knowledge of which is actual.

Last edited by John West (9/07/2016 4:50 pm)

Greg wrote:

It is true that he has all of the same real relations in all possible worlds. It doesn't follow that he doesn't know what is actual in the actual world, unless we suppose that God's knowledge of contingents is a real relation, which is what this resolution denies.

Since it's odd to say that God's knowledge is a relation (Cambridge or otherwise)*, I'll stick with “property”.

It seems plausible that if God knows something different in w than he does in v, his act of knowing is different in w than in v. Likewise, it seems plausible that if God creates something different in w than he does in v, his act of creation is different in w than in v. But if God is identical to his act of knowing or creation and those can differ, God can differ.

Well, I don't think that is the case. What it means for God to "really know" something contingent is for him to know it as something he has created, and his creation of contingents is a non-necessary concomitant of loving his own goodness. He has one and the same act of knowing in each possible world, but in different possible worlds, that act of knowing differs in its objects. In some possible world, its only object might be God. In others, its objects are God and creation. Its conditions of identity are given by what is necessary to it: that is an act of knowing the divine essence.

I think you're right that this is your cleanest reply: I just can't shake the suspicion that what's really doing the work here is that the problem has been defined out of existence.**

*It's odd to think of God's knowledge as some distinct thing outside of him.
**Also: “The identity condition for God's act of will and God's knowing (which are the same) is its being God's act of willing his own goodness and knowing himself; that these acts and knowings are also (in some possible worlds) willings to create and knowings of contingent facts is not what determines their identity." (see original)

Thanks for the reply, Greg:

They can be independently motivated, though. Peter Geach has this example meant to show that changes in a cause do not have to be proportionate to the changes in an effect (which thesis, if false, might give one the impression that no being could have active potentiality without having passive potentiality too). A professor lectures an audience; the effect of each student's learning is proportionate to its cause in the professor's knowledge. But the changes in the professor in the course of lecturing are incidental; if you add two students to the lecture hall in another possible world, the professor does the same thing, and undergoes the same changes, even though more knowledge is effected in more students. This example might be a helpful analogy for us too. Plausibly, in both of those possible worlds, the professor performs the same act of lecturing, even though his lecturing in each possible world engenders different knowledge in different students.

But what in the world makes the proposition that <The teacher is causing a student to learn> true? Since the teacher and student could have existed without ever meeting each other, it's not the teacher, the student, or the mereological sum of the teacher and student. Of the remaining options, I think it's probably the relational state of affairs the teacher causing the student to learn.[1]

I think Geach is right in his example. I think, however, that the reason is the asymmetrical nature of the causal relation itself, not that it's a non-real Cambridge relation.[2][3]

By the same truthmaker argument, knows that propositions also need relational states of affairs to serve as truthmakers. The difference, however, is that when those relational states of affairs hold, the knower knows something he otherwise wouldn't. In other words, Geach's example breaks down for knows that propositions' truthmakers.

Since we stipulate God's omniscience in advance, the knows that truthmaker argument seems to work for every entity except God. 

But allow me to register my disatisfaction with the idea that a relation that needs to be real in seemingly every other case of knowing, is a mere Cambridge relation with God.


[1]The other option is a relational trope, which works just as well for my argument here as a relational state of affairs.
[2]In fact I think causal relations are nonsymmetrical, but it doesn't make a difference to anything in this post.
[3]What makes <God caused the apple to change from green to red> true? Since both God and the apple could have existed without God causing the apple to change from green to red, it's not God, the apple, or the mereological sum of God and the apple. Once again, it's probably a state of affairs God causing the apple to change from green to red.

But then if you make it so that God has no real relations to creation, you've banned him from directly causally interacting with the created world apart from his initial creation of it. (And if you say that God can have real relations to the created world, what principled reason is left for denying that God can have the relations usually used to make knows that propositions true to it?)

Greg wrote:

Well, I neither know enough about truthmakers nor about states of affairs to respond to this in any way that satisfies me, but I am not sure what a state of affairs is besides the truth of a corresponding proposition

The idea is that we need something to unify the constituents (the teacher and student) in the relevant way, and that a relation alone is not sufficient for this. (For one, that would set you on Bradley's regress.)

so I am disinclined to treat states of affairs as truthmakers of propositions.

That's fine. That, however, leaves you with the only other option: relational tropes. My arguments work fine with relational tropes.

My sense is that it is both here, that the asymmetrical nature of the causal relation is the reason why causal relations can be Cambridge; I think I would not want to say that they must be, for causal relations will not be Cambridge relations when their objects specify the action, as is the case if the student is an object of the professor's deliberation and as is the case when God wills his own goodness. It is possible, if the student furtively left the room, for the professor to lose the property "is teaching the student" without a change on his part; thus that would be a Cambridge change.

The trouble is that on any theory of truth that respects reasonably healthy realist intuitions, you're going to run into something like the truthmaker argument. And if it goes through, the states of affairs that make the causal propositions true involve a real relation.[1]

(I'm mainly concerned with whether the causal relations are real, or not. I only mentioned Cambridge because it has been suggested that Cambridge relations aren't real relations.)


[1]I've put this argument in analytic terms, but with a few small changes you can find later medieval scholastics throwing versions of it all over the place; Chatton, in particular, argued like this all time. If, however, you want to opt for a more deflationary theory of truth, you're welcome to present it and we can argue about that.