Can Theistic Explanations Succeed? (part 6)

by Luke Muehlhauser on September 7, 2010 in Guest Post

Guest blogger John D of Philosophical Disquisitions summarizes contemporary articles in philosophy of religion in plain talk so that you can be up to speed on the God debate as it ensues at the highest levels of thought. This series was previously posted to John’s blog.


This post is part of my series on chapter 7 of Gregory Dawes’s book Theism and Explanation. In this chapter, Dawes assesses the strength of theistic explanations against a list of six explanatory virtues.

Part one, provided an introduction to this topic and also considered the explanatory virtue of testability. Part two considered the explanatory virtues of consistency with background knowledge and past explanatory success. In neither case did theism fare well.

In this post we will look at theism in light of the explanatory virtues of simplicity and ontological economy.

1. What is Simplicity?

The simpler the hypothesis, the more inclined we are to accept it. But which is the simpler hypothesis? It is usually understood as being the hypothesis that posits the fewest number of distinct entities and properties. That, at least, is Richard Swinburne’s approach to simplicity.

But this is not what Dawes means by simplicity. He defines simplicity in terms of falsifiability and auxiliary hypotheses. He takes this definition from the work of Karl Popper and Paul Thagard. According to this definition, a hypothesis is simple if it is readily falsifiable and relies on as few a number of auxiliary hypotheses as possible.

This might be a little opaque, so let’s consider an example. Suppose you have recently developed a plant fertiliser. You are adamant that it will dramatically increase the rate at which my plants grow. I decide to put it to the test. I set up a rudimentary controlled experiment in which I give some plants your fertiliser, some plants a standard fertiliser and some plants nothing at all. I try to hold constant other relevant factors such as access to sunlight and water.

Much to my chagrin, after several weeks there is no discernible difference in growth rates. I come back to you with these disappointing results. You respond by saying that I wasn’t using the fertiliser properly. It must be administered in the dark and at a temperature below 5 degrees celsius.

I take this new information on board and initiate a new test. After several weeks of the new regime there is still no discernible difference in growth rates. Feeling slightly aggrieved at having wasted so much time, I return to you once more with my results. You respond again by suggesting that I am not using it properly. I must also talk to my plants while administering the fertiliser and then play classical music to them when I am not around.

At each stage in this process, you are introducing auxiliary hypotheses that make it more and more difficult for your original hypothesis to be falsified. And so you are making your hypothesis less and less simple.

2. Is Theism Simple?

How well do theistic explanations fare in terms of simplicity? To answer this question, it will be instructive to consider a debate between Peter Van Inwagen and Paul Draper.

Back in 1989, Draper presented an argument suggesting that certain observations we have made concerning the biological utility of pain are more surprising on the hypothesis of theism than they are on the hypothesis of indifference. I will be covering this argument over at soon so I will not explain it here. All that needs to be said here is that Draper’s argument is an evidentialist form of the problem of evil.

Van Inwagen responds to Draper’s argument by introducing a series of auxiliary hypotheses that account for the presence of pain. These auxiliary hypotheses posit a set of possible reasons God might have for allowing pain to exist. These auxiliary hypotheses are usually called “theodicies”. Van Inwagen doesn’t claim that these are in fact true, he just thinks they could be true “for all we know”. And this is enough to save the hypothesis of theism.

This is not a promising approach. If it is accepted, then theism will score low in terms of simplicity. To retain any explanatory merit, these auxiliary hypotheses will need to score highly in terms of the other explanatory virtues.

It is interesting to note that one reason why Van Inwagen does not find the idea of positing auxiliary hypotheses to be problematic is that he is not an evidentialist. He follows Plantinga in thinking that we know of God’s existence in a properly basic manner. Because of this, evidence is to be treated in terms of damage control: what do we need to deny and what can be explained away?

Van Inwagen’s approach might be shared by many theists. They will not typically believe in God because he happens to be the best explanation for a set of facts. They will believe for psychological and emotional reasons. So when challenged with events and states of affairs that seem to be inconsistent with their idea of God, they will be happy to invent a plethora auxiliary hypotheses.

The obvious question is the following: once you have added-on all these auxiliary hypotheses, are you left with something worth believing in?

3. Ontological Economy

So much for simplicity, now we have to consider the virtue of ontological economy. What Dawes means by this comes close to what Swinburne means by simplicity, but it is slightly different. What he means is that when explaining something we should not introduce new kinds (types) of ontological entity (or process) unless we have sufficient reason to do so.

Dawes cites two examples suggesting that this is an acceptable restriction to place on successful explanations. The first comes from the work of Charles Lyell, one of the founders of modern geology. Lyell argued that when explaining how the earth got to be the way it is, we should do so in terms of processes that we can still observe today.

We should be wary about suggesting that there were different ontological processes in the past because that would open the door to “the utmost license of conjecture in speculating on the causes of geological phenomena.”

The second of Dawes’s examples comes from the work of Thomas Aquinas. Dawes notes that in considering arguments for the existence of God, Aquinas accepted the virtue of ontological economy. So point here is that we shouldn’t be apologetic about using this explanatory virtue since it is something that theists can accept.

Now, it should be borne in mind that this virtue is not intended to be an explanatory straitjacket: we can posit new ontological entities and processes if there is sufficient reason to do so. “Sufficient reason” would mean satisfying the other explanatory virtues such as testability, simplicity, informativeness and so on.

Of course, it should not come as a surprise to learn that theism does not fare well on the ontological-economy-front.

Okay, that’s it for this post. In the next part of this series we will consider theism in light of the final explanatory virtue: informativeness.

- John Danaher

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{ 8 comments… read them below or add one }

Chris K September 7, 2010 at 9:27 am

What are the reasons for accepting the Dawes/Popper/Thagard version of simplicity rather than Swinburne’s version? I happen to be a bit suspicious of Swinburne’s account of simplicity, but that’s probably because I’m a bit suspicious of simplicity as an overriding explanatory virtue anyway.

Back to the God of the philosophers/God of Abraham dichotomy, I would tend to agree that the former is a simple hypothesis, while the latter is not. However, I also think that the bare concept of the God of the philosophers just is identical to the God of say, biblical Christian theism. The second is just a more fleshed out concept of the bare-bones first one. So when ‘austere’ theism can’t answer questions like the problem of evil, it’s not surprising for theists to turn to the more robust theism. The question for us theists, then, is can we have our cake and eat it too? Can we both posit God as a simple explanation while at the same time having a more complex explanation that meets the more complex inquiries?

Further, the ‘auxiliary hypotheses’ aren’t ‘invented’ or ‘added-on’ in some ad hoc manner. The bare theistic hypothesis simply refers to the fuller, more complex explanation that, say, biblical Christianity has to offer. For example, the problem of evil: the austere theist can say, “You ask about evil? Let me refer you to Job (or something of the sort). It turns out that evil isn’t a surprise for this tradition.” So the analogy of the auxiliary hypotheses doesn’t seem quite right, or at least what we have is a simple explanation that refers to a complex one rather than a simple explanation that has to keep expanding to keep up with the data.

Finally, maybe I missed something – what’s the problem with ontological economy? If it’s acceptable by theists, why doesn’t theism fare well according to it?


Garren September 7, 2010 at 9:45 am

How does this hypothesis complexity model apply to the historical Jesus debate?


G'DIsraeli September 7, 2010 at 10:27 am

What if the truth is complex? Somebody has gotta explain to me how explanatory virtue except being useful has anything to do with truth value…


Garren September 7, 2010 at 10:33 am


It sounds more like a question of truth-discovery, rather than a limitation on what sorts of things might be true.

The plant fertilizer used as an example might really have a wonderful effect when used under the right conditions, but the complexity of the hypothesis makes it difficult to determine.


G'DIsraeli September 7, 2010 at 12:44 pm

Garren ,

Emm…So I’m confusing epistemology with metaphysics?
And isn’t that a value claim?
Any reference? Thank you


Adito September 7, 2010 at 1:08 pm

I’m not sure we gain much by redefining simplicity to support the argument. All that does is take things back one step were we now have to argue about simplicity.


Garren September 7, 2010 at 1:23 pm


Yes, the topic is simplicity of hypotheses, which indicates we’re talking about epistemology.

The phrase “explanatory virtues” in the blog post does hint at a value claim, but I would rather treat it as a useful distinction, i.e. it’s helpful to note whether a hypothesis is relatively simple or complex. How is it helpful? Well, it could inform our choice of appropriate analogies. It might not be apt to compare a complex hypothesis to a more familiar simple hypothesis (or vice versa). Instead of saying “that doesn’t seem like an appropriate analogy,” we now have a specific terminology we can use to explain why.

I brought up the historical Jesus debate because I suspect skeptics often hold complex hypotheses and use Van Inwagen style “for all we know” auxiliary hypotheses when we speculate on what really happened.

I advise caution before skeptics insist on any sort of principle that it’s an intellectual fault to hold complex hypotheses, in case it turns out we want to do so too.


Charles September 7, 2010 at 1:55 pm

This is a rather poor definition for simplicity. Falsifiability should be its own criterion.


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