Thursday, January 5, 2017

Hume's Objections to the Design Argument (Part Two)

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(Part one)

This is the second in a two-part series on David Hume’s objections to the design argument. If you haven’t read part one, I would recommend doing so before going any further. To briefly recap, in part one I mentioned that Hume’s treatment of the design argument — primarily in his Dialogues but also in his Enquiry — is lauded by many. JCA Gaskin is particularly impressed by it and dedicates a good portion of his book Hume’s Philosophy of Religion to its analysis.

In Gaskin’s reading of Hume, there are two versions of the design argument with which to contend:

The Nomological Design Argument: which focuses on the order/regularity that is found in nature and argues that some designer must be responsible for it.

The Teleological Design Argument: which focuses on the purpose/adaptation that is found in nature and argues that some designer must be responsible for it.

Both versions of the argument are defended by the character of Cleanthes in the Dialogues. They are then challenged by the character of Philo (often thought to represent Hume’s own views). Gaskin identifies ten different objections to both design arguments in Hume’s writings. These ten objections are organised into four main groups, illustrated in the diagram below. We dealt with the first two groups in part one. Let’s now look at the other two.

1. Analogical Weaknesses
The nomological and teleological arguments rest on an analogy. In Cleanthes presentation, we are entitled to infer that there is some designer of the order/purpose that we see in the natural world because our experience with the artificial world tells us that whenever there is order/purpose there is some human designer behind it all. In other words, the arguments are explicitly constructed in such a way that the natural and artificial worlds are deemed to be similar enough to ground an analogical inference. Hume has several objections to this attempted analogy.

The first of his objections is (numbering continues from part one):

(5) The ‘Weak and Remote’ Problem: ‘The analogy between those objects known to proceed from design and any natural object is too weak and too remote to suggest similar causes.’ (Gaskin 1988, 27 - citing an argument found in several locations in the Dialogues)

To understand this objection we need to understand how analogical arguments work. They all have the following structure:

  • P1. Y is true in Case A.
  • P2. Case B is like Case A in all important respects (i.e. with respect to features X1…Xn).
  • P3. Therefore Y* (similar to Y in important respects) is likely to be true in Case B.

In my more detailed presentation of the design arguments in part one, I showed how this abstract structure could be applied to both the teleological and nomological arguments. This application is not important right now. The critical detail for now is how all analogical arguments depend upon a similarity claim. It is because Case B is similar to Case A with respect to features X1…Xn that the inference can be made. The more similar the two cases are, the stronger that inference is; the more different they are, the weaker it is.

Hume’s challenge to both versions of the design argument is to suggest that the two cases (natural order/purpose and artificial order/purpose) are not very similar at all. They do not share as many features as proponents of the argument like to suggest and those that they do share are, upon closer inspection, more dissimilar than we might first think. There are many examples of this in practice. The purpose we see in the design of non-human animals and plants can often be opaque and bizarre. Think about the instances of ‘bad’ design that we see in nature — examples like the laryngeal nerve of the Giraffe, the vestigial thumb of the Panda, and all manner of cruel and painful livelihoods that are eked out by predators and prey. These examples are all better explained by Darwinian evolution, of course, but if we set that to the side and seriously entertain the design hypothesis we have to acknowledge that we are dealing with a designer with very different purposes or intentions to any human designer — ones that are ‘beyond our ken’.

On top of this, there is a scale and immensity to the order we see in the universe that makes its construction something quite beyond the abilities of any human designer. This might seem to warrant the inference to a supreme being with the powers traditionally attributed to God, but for Hume the dissimilarities of scale serve to undercut the analogy used to ground the design argument:

All the new discoveries in astronomy, which prove the immense grandeur and magnificence of the works of nature…become so many objections, by removing the effect still farther from all resemblance to the effects of human art and contrivance. 
(Hume’s Dialogues — quoted in Gaskin 1988, 30)

This brings us to the next objection:

(6) The Non-Agential Order Problem: ‘Order, arrangement, or the adjustment of final causes is not, of itself, any proof of design; but only so far as it has been experienced to proceed from that principle.’ (Hume’s Dialogues - quoted in Gaskin 1988, 31)

This is a little bit tricky to understand. Hume makes two points in relation to this objection. The first is that when you look at the totality of human experience, the evidence we have for thinking that order/purpose proceeds from agency is pretty flimsy. The second is that we have some reason for the thinking that order can be brought into existence without agency. Both points require some elaboration.

The first point is probably the more subtle one and its significance may be underappreciated. Look around the world. Look at all the instances of order/purpose that you find in it. How many of those instances of order/purposes are known — independently of the design argument — to proceed from agency? The answer is very few (proportionately speaking). Humans have had a remarkable impact on the world around them, but it is still true to say that the natural world (including the universe as whole) is much larger than the human created world and contains in it many instances of order/purpose that are not known — independently of the design argument — to proceed from agency. This is a problem because the strength of the analogy underlying the design argument is dependent on the totality of the available evidence regarding design in the universe. It’s only if we are more certain, based on our experience, that design is brought about by an agent that we can infer that all instances of design must have an agential origin.

Another way of putting it might be like this: we frequently reason from samples of the whole to explanations of the whole. We are entitled to reason from small samples if there are good grounds for thinking that they are representative of the whole (think about the way in which polling data is collected from samples). But in the case of the design argument, there is no good reason for thinking that the small sample of human-created design is representative of the whole. On the contrary, the total background evidence we have suggests that most instances of design do not have an agential creator. So we cannot reason by analogy from the few cases of human-created design to the assumption that there is a designer for the whole.

The second point Hume makes is more straightforward. It is simply that there are known cases in which order is brought about by non-agential forces. Certain geological processes, for example, are non-agential and yet can result in orderly patterns. Similarly, most people would agree that plants are not agents and yet when they grow and develop, plants create order in the world around them. So here we have some direct counter-analogies: cases in which design is not the product of a designer.
Some theists might object to this on the grounds that these examples all involve new forms of order/design being created from previous forms of order/design. Thus, the non-agential forces to which Hume appeals do not explain the origins of order/design in the first place. That’s as may be, but in making this move, the theist is shifting to a different kind of argument — something more akin to the cosmological argument — which tries to suggest that there must be a first link in a chain of causation. The regress problem — discussed below — challenges this style of argument.

The last of Hume’s three analogical objections is this:

(7) The Tightrope Problem: The design arguments try to walk a very fine line between excessive anthropomorphism and incomprehensible remoteness when it comes to the nature of the designer. It is very difficult to walk this line and maintain the credibility of the design argument.

This objection functions like a dilemma. Suppose the theist is right and the analogy between artificial order/purpose and natural order/purpose is strong. In that case, the strength of the analogy means we should infer a very human-like designer. We would then end up with something that falls a long way short of the supreme being beloved by theists. Contrariwise, suppose the theist is wrong and the analogy is not strong — the scale and magnitude of the universe points to a being with properties very distinct from a human creator. In that case, they might be able to get to the supreme being they desire, but at the cost of undercutting the analogy they were originally using to support their case.
So theists have to walk a very fine line — a tightrope if you will — one that insists that the two cases are just similar enough to warrant the inference to a designer and also different enough to enable them to insist that the designer is a supreme, non-human like being.

In fact, for Hume, it gets worse than that because not only do theists have to walk that line when it comes to the design argument, they also have to walk that line with their very conception of God. The God they want has to be human-like in some ways (with a human like mind/personality and moral interests in humanity’s affairs) but also practically incomprehensible and ineffable in others (omnipotent, omniscience, perfectly simple etc.).

2. Problems in Explaining Order/Purpose
This brings us to the final branch of Hume’s taxonomy of objections. There are three specific objections lying along this branch. Each of them takes issue with the motivation behind the design arguments, i.e. the desire to explain order/purpose in terms of divine agency. They each take a slightly different perspective on the issue though.

The first objection points to a general problem with all attempts to explain order/purpose:

(8) The Regress Problem: “If an intelligent agent is required to explain the order in nature then the intelligent agent will in turn need to be explained…But if we stop at the agent explanation, and go no farther; why go so far? Why not stop at the material world? How can we satisfy ourselves without going on in infinitum? And after all, what satisfaction is there in that infinite progress?” (Hume’s Dialogues - quoted in Gaskin 1988, 41)

The point that Hume (via Philo) is making in this quote is a familiar one. Anybody who has spent anytime sniffing around the philosophy of religion will have encountered some variant on it before. Hume is saying that explanations must bottom out somewhere, i.e. with some fundamental origin or source for the order/purpose we see. Theists want the explanation to bottom out in God: they want him to be the ground of all being. But do they have good grounds for doing so?

Hume thinks that they face two problems. First, in trying to get to God they appeal to principles that do not justify stopping with God. Thus, as noted above when discussing their objection to Hume’s plant example, they will suggest that there must be some fundamental origin to the order/purpose we see in the universe: an explanation that doesn’t just explain one type of order in terms of another type of order. They think God satisfies this role, but Hume argues that he doesn’t. What is God if not an ordered, purposeful being? Appealing to Him means that we explain one type of order in terms of another type of order. But if order itself needs to be explained then we will need to find some explanation for God. Hence, the infinite regress. Some theists might think they have a response to this by arguing that God is a perfectly simple, unitary being and hence doesn’t display the kind of ordered complexity that they think is needs to be explained. But Hume has a reply to this:

A mind whose acts and sentiments and ideas are not distinct and successive, one that is wholly simple and totally immutable, is a mind which has no thought, no reason, no will, no sentiment, no love, no hatred; or, in a word, is no mind at all.
(Hume's Dialogues, Part IV) 

The other problem that theists face is that if they accept that there cannot be an infinite regress of explanations, they will need to justify going beyond the laws of nature in explaining the order/purpose we find in the universe. As Hume puts it: If we have to stop somewhere, ’why not stop at the material world?’ We might be justified in seeking a further explanation for the laws of nature if the explanation we posit can provide us with greater insight/understanding of those laws. But Hume argues that God does not provide this additional insight. On the contrary, God is usually a deeply mysterious explanation, with little or no explanatory power or predictive potential. Of course, theists disagree, but I tend to think Hume is right on this score: appeals to the explanatory power of God are usually little more than an attempt to explain one mystery in terms of something even more mysterious.

The next objection takes a different tack and suggests that there are, in any case, alternative naturalistic explanations for the order/purpose we see in the universe:

9. The Alternative Explanations Problem: There is a ‘system, an order, an economy of things, by which matter can preserve the perpetual agitation, which seems essential to it, and yet maintains a constancy in the forms’ (Hume’s Dialogues - quoted in Gaskin 1988, 43)

This is obscurely expressed but it is the shortest summary of one of Philo’s more complex arguments in the Dialogues. In one sense, what Philo argues is more appealing to us nowadays than it was in Hume’s time. Remember, when Hume wrote the Dialogues Darwin was yet to expound his theory of evolution by natural selection. This theory — and subsequent developments of it — provided a compelling (to most, at any rate) naturalistic explanation for the purpose and adaptation we see in the living world. Hume had to defend an alternative naturalistic explanation without the benefits of Darwinism. But Gaskin argues that Hume anticipated Darwin’s ideas in the following passage:

It is vain, therefore, to insist upon the uses of the parts in animals and vegetables, and in their curious adjustment to each other. I would fain know how an animal could subsist, unless its parts were so adjusted? Do we not find, that it immediately perishes whenever this adjustment ceases, and that its matter corrupting tried some new form? 
(Hume’s Dialogues — quoted in Gaskin 1988, 44)

Did you spot the anticipation of Darwin? It’s a little hard to see, but in this short quote Hume does mention two things that are redolent of Darwinism. First, he points to something akin to a Darwinian selection pressure when he says that he would ‘fain know how an animal could subsist [i.e. survive], unless its parts were so adjusted?’. Second, he seems to suggest that something akin to mutation (‘matter corrupting’) could be responsible the animal forms that survive and subsist. This is, of course, a generous interpretation, conducted with all the benefit of hindsight.

In any event, offering a naturalistic explanation for the purpose and adaptation we see in living nature is only half the battle. There is still the question of where all the order and regularity in the universe as a whole came from. Here, it seems that Hume paid homage to the classic Epicurean view. According to this view, the universe is an infinite soup of matter in motion. Much of that motion is chaotic and disordered. But if the universe is truly infinite, there will, of necessity, be localised pockets of order and we, as ordered beings, will necessarily find ourselves in those localised pockets. Thus, in an infinite universe in which all possibilities are eventually tried out, there is nothing explanatorily surprising about our existence:

Thus the universe goes on for many ages in a continued succession of chaos and disorder. But is it not possible that it may settle at last, so as not to lose its motion and active force…yet so as to preserve a uniformity of appearance amidst the continual motion and fluctuation of its parts? This we find to be the case with the universe at present…May we not hope for such a position, or rather be assured of it, from the eternal revolutions of unguided matter, and may not this account for all the appearing wisdom and contrivance which is in the universe? 
(Hume’s Dialogues — quoted in Gaskin 1988, 46)

The challenge for this Epicurean view lies in contemporary cosmology. We know much more about the universe in which we live now than we did in Hume’s day. The scientific evidence we currently have suggests that our universe started at a finite point in the past and that the matter within it obeys fairly uniform laws. This seems to rule out the possibility of the infinite, churning chaos that Hume requires. But this isn’t quite right either. Our current scientific model of the universe is incomplete in certain important respects and the finite duration of the portion of the universe in which we live and do our science doesn’t rule out the possibility that we are part of some larger, infinite chain of universes or multiverses. Indeed, some scientific theories point in that direction already. So the Humean alternative may still be viable, and I find it appealing on philosophical grounds (viz. positing an infinite chaos in which everything that is possible happens seems like the neatest and most satisfactory explanation of everything).

Hume has one last objection to theistic attempts to explain order/purpose:

10. The Cognitive Limitation Problem: Human reason is a poor instrument for working out universal truths. We should be sceptical of all our attempts to explain the ultimate origins of reality.

This is theme that runs throughout Hume’s philosophical works. He is the arch-sceptic. He thinks that human reasoning is weak and highly fallible. It doesn’t deliver the results we would like. We cannot even justify simply practices like scientific induction on the basis of reason alone. Consequently, we should be very sceptical of any attempt to use these weak and fallible capacities to explain the origins of order/purpose.

I’m not sure if I completely follow Hume on this front. I think we should be sceptical of the powers of human reason but I tend to sympathise more with the view Hume attributes to Cleanthes in the Dialogues, namely: complete scepticism is unwarranted and human reason can provide us with some insights. It’s really all about the domain of inquiry: whether human reason is up to the task in that domain. I might agree with Hume that religious matters are one area where human reason is not up to the task. JL Schellenberg is probably the contemporary philosopher who has done the most to take up Hume’s cudgels on this front. His book The Wisdom of Doubt presents the best argument I know of for religious scepticism of the Humean type (though note: Schellenberg is more optimistic about the long-term prospects for human reason). I recommend it to anyone who would like to pursue this tenth line of objection in more depth.

3. Conclusion

That brings us to the end of this analysis of Hume’s objections to the design argument. To sum up, Hume focuses on two versions of the design argument: the nomological and the teleological. The former is concerned with the order/regularity we observe in the natural world; the latter is concerned with the purpose/adaptation we observe in the natural world. Hume levels ten objections against these two arguments. These objections have been discussed in detail over the two posts in this series. I won’t repeat the details here.

As you no doubt noticed, there are parts of Hume’s critique that are quite antiquated. He concerned himself with the religious debates and views of his day and he wrote at a time when our scientific understanding of biology and cosmology was in its infancy. Nevertheless, much of what he says continues to have relevance, and it always amazes me to see how closely Hume’s reasoning resembles or anticipates what we find in contemporary philosophy of religion.

Let me close, however, on a more critical note. Hume deals with an explicitly analogical version of the design argument in his writings. One problem with this is that most modern defenders of the design argument abjure the analogical form. They favour arguments that are couched in Bayesian terms or in terms of inference to best explanation. It sometimes turns out that these formulations of the argument rely, implicitly, on some analogy between human design and divine design, but to reveal that implicit reliance you have to engage with some complex debates in probability theory and theories of explanation. I still think that parts of what Hume says are relevant to those debates, but it requires more work to demonstrate this.

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