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Recently, Joshua Rasmussen offered an original argument for the existence of a necessary being. Rasmussen states his argument as follows:
(1) Normally, for any intrinsic property p that (i) can begin to be
exemplified and (ii) can be exemplified by something that has a cause,
there can be a cause of p’s beginning to be exemplified.
(2) The property c of being a contingent concrete particular is an intrinsic
(3) Property c can begin to be exemplified.
(4) Property c can be exemplified by something that has a cause.
(5) There can be a cause of c’s beginning to be exemplified (1–4).
(6) If (5), then there is a necessary being.
(7) There is a necessary being.
In this paper, I shall argue that premise (3) lacks adequate support, and thus that Rasmussen’s new case for a necessary being is unsuccessful.
Two initial points of clarification about premise (3) are in order for our purposes. First, it’s important to emphasize that premise (3) is a modal claim. In particular, (3) asserts that a particular state of affairs is broadly logically possible, i.e., metaphysically possible. Second, the relevant state of affairs Rasmussen asserts to be metaphysically possible is a beginning to the existence of all contingent concrete particulars. Rasmussen helps to further clarify the sort of state of affairs he has in mind by having us imagine “…a beginning to the existence of contingent bits of matter as they explode out of an initial singularity.” Putting these two points together, then, we see that (3) asserts that it is metaphysically possible that there is a beginning to the existence of all contingent concrete particulars.
I can think of two ways in which one might attempt to support (3). First, one might argue that it’s actually true that all contingent concrete particulars had a beginning to their existence, and since whatever is actually the case is possibly the case, it follows that it’s possible that all contingent concrete particulars had a beginning to their existence. So, for example, Rasmussen might say that we can appeal to scientific confirmation of the beginning of all contingent concrete particulars in the singularity described in standard models of the Big Bang theory of the origin of our universe. This is at least hinted at in his assertion mentioned above that, "...we can imagine a beginning to the existence of contingent bits of matter as they explode out of an initial singularity".
This brings me to my first criticism of premise (3). For unless one has adequate specialized training in the relevant scientific fields, one will likely not be competent to evaluate the evidence for this claim on one’s own. I take it that this applies to most of us; we must therefore defer to the relevant experts. But the problem is that there is significant divergence of opinion among the experts on this issue, as there is no consensus among them that our universe had an absolute beginning in a singularity.
The other way in which one might support (3) is by appeal to an inference from imaginability to possibility. As with the first line of support for (3), this sort of support also seems suggested by Rasmussen’s previously mentioned remark: one can imagine all concrete particulars having a beginning of existence in a singularity. According to this line of reasoning, then, our ability to imagine a scenario consisting in a beginning to the existence of all contingent concrete particulars constitutes sufficient prima facie evidence of its metaphysical possibility.
To evaluate the justification above for (3), we’ll need to distinguish between two different sorts of things one could be asked to imagine here: a beginning to the existence of the contingent concrete particulars of the actual world, or a beginning to the existence of those of some other. Assuming the truth of the other premises in Rasmussen’s argument, the possibility of either sort of state of affairs would suffice as the referent of (3) to reach Rasmussen’s conclusion that a necessary being exists; we will therefore have to evaluate the possibility of each.
Take the former first. The problem here is that we immediately fall afoul of the problem of imaginability-possibility inferences in a posteriori necessities contexts. To see this, suppose we give our universe a Kripkean baptism: We say (pointing to the universe), "Let that be called 'Uni'. 'Uni' is now a rigid designator, and thus refers only to our universe in all the possible worlds in which it exists. Holding our universe fixed via the term ‘Uni’, we can start considering modal claims about it. There are two relevant possibilities for us to consider in this regard: (i) Uni has its origin in the causal activity of a necessary being, and (ii) Uni has no origin. Now if (i) is true, then by origin essentialism, this is an essential property of Uni, in which case there is no possible world in which Uni lacks such an origin. On the other hand, if (ii) is true, then Uni lacks an origin in the causal activity of a necessary being, and so this fact about Uni is essential to it, in which case there is no possible world in which it has an origin in the causal activity of a necessary being. The moral, then, is that if we accept origin essentialism like good Kripkeans, then we will think that facts about whether our universe has an explanation in terms of a necessary being don't vary from world to world. But if so, then we can't know whether our universe could have a beginning unless we know beforehand that it in fact had a beginning.
The previous criticism seems to apply with some force to the second sort of candidate referent, i.e., the possible beginning of existence for some other possible universe distinct from our own. For if our modal imaginination is unable to probe the nature of our universe deeply enough to determine whether it can begin to exist, then there is reason to doubt that it could probe deeply enough into the nature of any other universe to determine whether it could begin to exist.
One might object that the previous criticism relies on an arbitrarily selective form of modal skepticism, on the grounds that the demand for justification for exotic possibility claims should then apply to the humdrum possibility claims as well. And since we accept the latter without argument, we should, to be consistent, accept the former. But this objection is unpersuasive. For a number of plausible accounts of our knowledge of possibility have been proposed that allow for knowledge of humdrum metaphysical possibilities, while leaving exotic possibility claims unjustified. For example, it has been proposed that our knowledge of metaphysical possibilities is grounded in (i) our facility with counterfactual reasoning in ordinary contexts, (ii) our folk theory of how the world works, and (iii) arguments from analogy/relevant similarity with the actual world. Such accounts can nicely explain the epistemic force of relatively uncontroversial thought experiments involving humdrum metaphysical possibilities (e.g., the Gettier cases), while leaving the more "far out" or exotic modal claims unjustified (e.g., "it is possible that I exist apart from my body", "it is possible that an Anselmian Being exists", etc.). Most saliently for our purposes, it appears that such accounts leave Rasmussen's modal claim involving the possible beginning to the existence of all contingent concrete particulars unjustified: it's not clear how such a claim could be justified via relevant similarity with the actual world, our folk theory of how the actual world works, or our facility with counterfactual reasoning in ordinary contexts.
Finally, it's not clear that all of the non-necessary particulars are contingent in the sense required for the truth of (3). To see this, consider the following epistemically possible scenario: There are just two sorts of concrete particulars within the space of metaphysically possible worlds: contingent dependent beings (e.g., rocks, trees, planets, galaxies, you and me, etc.) and contingent independent, “free-standing” beings, out of which all the contingent dependent beings are composed (perhaps matter-energy is like this). In this scenario, then, the contingent dependent beings come into being when two or more contingent independent beings are combined, and they cease to exist when they decompose into their elements. However, the elements of which they're composed -- the contingent independent beings -- can't pass away, for while there are possible worlds at which they don’t exist, they are eternal and indestructible at all possible worlds in which they do exist.
The account of contingent concrete particulars above is epistemically possible. But if so, then since such an account, if correct, entails that not all contingent concrete particulars can have a beginning of existence, the scenario serves as an undercutting defeater for premise (3) of Rasmussen's argument.
In conclusion, I have argued that Rasmussen’s new case for a necessary being is unsuccessful. The main reason is that it relies on a modal premise that lacks sufficient justification from both armchair and scientific sources. Unless Rasmussen can offer such justification, the argument will remain unpersuasive.
 Rasmussen [2010: 1-6].
 Rasmussen [2010: 1-2].
 Rasmussen [2010: 4].
 Rasmussen [2010: 4].
 There are several alternative models to the standard Big Bang model that don't involve the origin of the universe in a singularity, but here's one. According to M-theory (the theory that unifies the five versions of superstring theory), there are entities called 'branes', or multi-dimensional membranes (ranging from 0 (for point-particles) to 10 dimensions, and our universe is just one 4-dimensional brane among many branes existing within a larger 11-dimensional space-time. Thus, according to M-theory, the beginning of our universe is not the absolute beginning of concrete particulars, and the realm of concrete particulars may well have no beginning. On M-theory, then, the need for an absolute temporal beginning of concrete particulars doesn't arise. For a popular account of M-theory, see, e.g., Greene .
 Rasmussen [2010: 4].
 One could of course reject origin essentialism, or restrict its scope in a way favorable to the argument, but then the worry is that the audience for the argument will shrink considerably.
 Williamson .
 Williamson ; Hanrahan [2007: 125-146].
 Hawke [forthcoming].
Greene, Brian 2003. The Elegant Universe, New York: Norton & Norton Company, Inc.
Hanrahan, Rebecca 2007. "Imagination and Possibility", The Philosophical Forum 38/2: 125-146.
Hawke, Peter forthcoming. "Van Inwagen's Modal Skepticism", Philosophical Studies (forthcoming).
Rasmussen, Joshua 2010. “A New Argument for a Necessary Being”, Australasian Journal of Philosophy 88/3: 1-6.
Williamson, Timothy 2008. The Philosophy of Philosophy, Oxford, UK: Oxford University Press.