The teleological/fine-tuning argument for God’s existence runs something like this: Look at how amazing the universe is! Look at how the universe had to be just right to turn out to be the kind of place that could sustain life! Isn’t it unlikely that our universe could arisen this way by pure chance? Therefore, God.¹
A standard response to this argument is to suggest alternative cosmological theories that make it less unlikely that we happen to be in a universe that can sustain life. One example of this kind of theory is the multiverse theory. According to this theory, there are many universes and we happen just happen to be lucky enough to be in the universe that can sustain life.
The idea here is that this theory makes it far less unlikely that there is a universe like ours, that is, a universe that can sustain life. After all, if the cosmos has multiple shots at creating a life-sustaining universe, then its not crazy to think that the cosmos will eventually “hit” on the right combination of physical laws so that I can exist and type this silly blog post that no one will ever read. Thus, the multiverse theory looks like it can explain why there happens to be a life-sustaining universe in the cosmos.
At this point, however, all we have are two competing hypotheses that explain why we find ourselves in a life-sustaining universe. If both of these hypotheses explain the phenomena equally well, then parsimony will settle the tie-breaker. The multiverse theoriest will boast that their hypothesis doesn’t require the positing of a god, and thus, their theory wins out.
After writing a paper for one my classes this semester, I am no longer sure that this is all that can be said about this particular conversation.² For one thing, we might distinguish between two kinds of parsimony: qualitative parsimony and quantitative parsimony.³ Once we make this distinction, we can ask some interesting and important questions that can move the aforementioned conversation forward.
A theory that is qualitatively parsimonious posits the existence of fewer kinds of entities. Since God is an entirely different kind of entity than those found in the natural world, religious hypotheses are less parsimonious in the qualitative sense. Quantitative parsimony, on the other hand, is parsimony with respect to the number of entities in a world. If I suppose that there are multiple universes, I am endorsing a theory that is less quantitatively parsimonious than a theory which supposes that there is only one universe. Thus, it seems clear that the multiverse theory fares worse than the god theory in terms of quantitative parsimony.
Moreover, this seems to count for in favor of the religious hypothesis. After all, surely quantitative parsimony counts for something. If two theories explain some phenomena equally well, it seems like we should favor the theory that posits a fewer number of entities.
Now, here’s a question: Which theory is more rational to endorse? A quantitatively parsimonious one or a qualitatively parsimonious one? The multiverse theory wins out on qualitative parsimony, but not on quantitative parsimony. The religious theory, vice versa. Which one is rational to believe?
Answering this question requires a closer look at the philosophical justification for favoring parsimonious theories in general. I’m not really familiar with how philosophers have traditionally done this, but I do have one reason why we might think parsimony is important: non-qualitatively-parsimonious hypotheses can be used to explain anything and there is no limit to the number of non-parsimonious hypotheses that could explain some phenomena.
I could explain my ability to walk as the product of invisible, intangible “step-leprechauns” that can read my mind and know when I want to take a step. Or I could just say that I have a brain that can communicate with the required nerve and muscle systems so that I can walk. To reject the importance of qualitative parsimony is to open up the possibility of having to take the leprechaun hypothesis seriously.
Can the same kind of problem arise with respect to quantitative parsimony? Can we generate non-quantitatively-parsimonious explanations for any phenomena? Its not obvious that we can. Thus, the philosophical justification (if there is one) for quantitative parsimony must lie elsewhere. The relative importance of quantitative parsimony to qualitative parsimony can only be determined once I find this justification, and that is something that I must look for on another day.
1. “Therefore, God.” is not the best way of stating the conclusion of the argument. It is perhaps better to say something like “Therefore, creator(s).” As Hume has pointed out, there could be multiple creators or the creator could be a jerk. My point, in short, is that we can’t get from a teleological argument to the God of (one kind of) Christianity.
2. The paper explored Russell’s account of our knowledge of the external world. Considerations of parsimony arose because Russell’s account posits infinite amounts of sense-data. However, Russell’s account is more qualitatively parsimonious in that it gets rid of Kant’s thing-in-itself. Here is where the question is which parsimony should be privileged first arose.
3. The terminology for this distinction was stolen from the Stanford Encyclopedia article on simplicity.