Here is John Turri’s argument for a necessary being, which captures the essentials of a previous argument by Joshua Rasmussen.
- It is possible that the first contingent thing is caused to exist. (Premise)
- In the possible case where the first contingent thing is caused to exist, a causally powerful necessary being must cause it to exist. (Premise)
- A causally powerful necessary being possibly exists. (From 1 and 2)
- A possibly causally powerful necessary being necessarily exists.
To see why 2 is true, notice that a prior contingent thing can’t cause the first contingent thing—for that prior thing would itself be the first contingent thing; therefore, only a necessary being could cause the first contingent thing. This seems like a valid argument; if you accept 1, the conclusion follows. So, we should focus on the controversial premise 1. As Turri notes, all the conclusion entails is that there is a necessary being that is causally powerful in some possible world and not in every world. In other words, there are other possible worlds where a necessary being is not a cause. (Modest premises in, modest conclusion out.)
There’s a simple—maybe too simple—response to this argument. Many people will have the intuition that there can’t be a concrete necessary being (using conceivability to possibility as a guide). People with this intuition will think that all concrete things are contingent; therefore, on this view, the first contingent thing can’t be caused to exist—for there would have to be a causally prior contingent thing that would itself be the first contingent thing. Simple.
This may seem all too quick and some may still have the intuition that the first contingent thing can have a cause—for suppose the first contingent thing is a water molecule: Why isn’t it possible that the first contingent water molecule be caused by, say, the prior bonding of a hydrogen and oxygen atoms? (The water molecule example comes from Joshua Rasmussen.)
Consider this parody:
1’. It is possible that the first non-infinite-sized thing is caused to exist. (Premise)
Suppose the first non-infinite-sized thing is caused to exist. It’s possible that that first non-infinite-sized thing is a tiny water molecule. You may have the intuition that this water molecule could be caused to exist by the bonding of hydrogen and oxygen atoms. But the thing that caused the water molecule to exist can’t also be non-infinite-sized—for if that were so, then that thing would be the first non-infinite-sized thing; therefore, only an infinite-sized thing can be the cause of the water molecule. The truth of 1′ entails the possible existence of an infinite-sized (and causally powerful) thing.
Returning to 1 … suppose that the first contingent thing is a water molecule. We have the intuition that this water molecule could be caused to exist by the prior bonding of hydrogen and oxygen atoms. If we keep with this intuition, we’ve just shown that hydrogen and oxygen are necessary beings—and the proofs for other necessary beings wouldn’t stop here.
Consider another parody:
1’’. It is possible that the first non-square-circled thing is caused to exist. (Premise)
For simplicity, we can use the water molecule as an example of the first non-square-circled thing. An unsuspecting reader might have the intuition that this water molecule could surely be caused to exist. But this can’t be right, since it would prove the possible existence of a square-circled thing. This shows that—in thinking of the entailments—we should consider the conclusion (the possible existence of a square-circled, causally powerful thing) in advance, if we want to accurately assess 1’’.
If we reason this way, then 1’’ (and 1) should not persuade someone who is already skeptical of the conclusion. In 1, what first seems like an independent argument for a necessary being is not one anymore than 1’’ is an independent argument for a possible squared-circle.
Turri, John. “A New And Improved Argument For A Necessary Being.” Australasian Journal of Philosophy 89.2 (2011): 357-359.
Rasmussen, Joshua. “A New Argument for a Necessary Being.” Australasian Journal of Philosophy 89.2 (2011): 351-356.