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Intelligent Design and the Logic of Hume’s Skepticism

In the city of Edinburgh there is a statue of the philosopher David Hume. Many remember him as a pioneering freethinker who saw through the superstition and sectarian dogmatism of religion. Therefore many visitors make a special and ironic point of rubbing his toe for luck. Amongst other things, he was an early denier of intelligent design. But I think some of his modern fans would be surprised to know why.

Long before Charles Darwin made it possible, per Richard Dawkins, to be an “intellectually fulfilled atheist,” Hume wrote a book titled Dialogues Concerning Natural Religion (1779). Natural religion or natural theology is not the same thing as intelligent design. It is the attempt to understand the higher power (God, defined very broadly) from what we see in the natural world. Proponents of natural theology were interested in all sorts of questions including divinity, transcendence, goodness, and miracles. Hume argues that most of these questions are beyond our capacity to evaluate as humans, since they are beyond our experience. (When was the last time you saw someone create a universe ex nihilo?)

I am not going to try to answer Hume on that, except to point out that intelligent design is different, because it is something we are all familiar with. We design and make things. We create art and engineering and software, and so ID is not beyond our ability to understand. Intelligence and design are things we see in others and all around us. Since most of the book is irrelevant to ID, I am going to ignore most of it. There is only one real argument against ID, but it is an extraordinary one and it has some extraordinary implications today.

An Extraordinary Argument

In the book, Hume speaks through a fictional character, Philo, in debate with two conversational partners: Demea and Cleanthes, who represent two different types of religious person. Cleanthes is the 18th-century (religious) ID proponent, and Demea is the 18th-century (religious) ID skeptic. It is funny to think that religious opposition to ID-thinking is nothing new! Among the three of them, they have a wide-ranging debate about what can and cannot be inferred from observing nature. 

Demea likes to argue that God is utterly mysterious, beyond the ability of science to detect. Philo heartily agrees (though with a barely disguised smirk). 

Cleanthes argues that there is evidence for design throughout nature. He argues the case pretty well; not bad for a fictional character created by the pen of an atheist. But then again, the basic argument for design has never been obscure. Cleanthes argues that in all our experience, order, complex arrangements, and fitness-to-purpose come from the skill of a craftsman or an artist; an intelligent agent. From this knowledge and from all the exquisite beauty and design of the universe we may reasonably infer that a divine craftsman and artist exists.

But Philo is skeptical. He argues that the further we get away from day-to-day life, the less reliable is our ability to make inferences about reality. He points out that there are dangers of making presumptions everywhere, and does his best to deconstruct Cleanthes’ arguments. 

Rationality or Life?

Cleanthes had argued for an analogy between natural order and human-designed mechanisms such as clocks. Philo acknowledges that the analogy has some validity, but then he argues that there is a better analogy.

According to Philo there are four known kinds of causes in the universe: reason, instinct, generation, and vegetation. Reason (or rationality) is the word for both mechanism and intelligence: the incredible abilities of human beings and the things that we make are due to our reason. The lesser abilities of animals are due to instinct. But however smart we humans or animals are, we are not created by reason or instinct; we are born and grow, reproducing from parents by a “principle of generation.” Likewise, plants contain wonderful architecture, but they also grow by a similar principle. In both cases the offspring is similar to, but not exactly like, the parent. The outcome of reproduction does not seem to be rigid clockwork as one would expect from a mechanism. Philo then speculates wildly that maybe even the order of astronomical bodies and even whole universes might be generated by another, as yet unknown, inherent principle of reproduction; one which involves no intelligent designer. Get this:

In like manner, as a tree sheds its seed into the neighbouring fields, and produces other trees; so the great vegetable, the world, or this planetary system produces within itself certain seeds, which, being scattered into the surrounding chaos, vegetate into new worlds. A comet, for instance, is the seed of a world; and after it has been fully ripened, by passing from sun to sun, and star to star, it is at last tossed into the unformed elements, which everywhere surround this universe, and immediately sprouts up into a new system. 

I kid you not. The great vegetable. What fun it must have been to be a freethinker in the 18th century. 

Biology as Prior to Rationality

Now here comes the key argument. Philo argues that reason (that is, rationality, intelligent design seen in the form of mechanism) encompasses only a tiny proportion of the universe — the things created by human beings. A much greater part of the universe that we see is described by biological principles: by autonomous growth and reproduction. Moreover since it is birth and growth that gives rise to humans with reason, this alone should tell us that the biological principles are prior to and deeper than any reason or design. In a nutshell: biological life comes first; intelligent design comes last. I can feel the persuasive power of this argument, and it is an evolutionary Weltanschauung, long before Charles Darwin.

But notice what the argument implies: Philo is suggesting that life is not explained by a particular arrangement of parts (as that would imply a designed object or artifact) but by some deeper natural principle that is more fundamental than rationality and therefore also deeper than mechanism or deterministic natural law, and prior to both.

This is vitalism. Moreover, it is the opposite of where science at the time was leading. Science was exploring the Newtonian “mechanistic” view of the universe. That is the view which had inspired people to think of God as a “clockmaker” designer (and then, as technology improved, a “watchmaker” — as now we might think of a software engineer). David Hume was resisting that trend with all his intellectual might. Let me repeat: David Hume was making a philosophical argument for moving in the opposite direction from the one in which practical human knowledge was leading us. Put that in your pipe and smoke it for a little while. 

David Hume Becomes an ID Proponent?

It is cheap to tar someone with an unpopular label like “vitalist.” The more significant development is that we have since discovered that much more of the universe is “rational” than Hume knew. It isn’t just the motion of planets that bears analogy to the detailed genius of a clockwork mechanism. In particular, we now know that the basis of life itself is a very complex network of molecular machinery. More than machinery, we see digital code, made all the more remarkable by parallel developments in human technology. It turns out that the “principle of generation” is definitely not a fundamental law or property of the universe. Instead, it depends on an extremely complex arrangement of parts; a design. 

Besides that, we never found any biological analogy for cosmology, though incredibly some are still trying (consider bubble universes, for example).

Of Philo’s four efficient causes — reason, instinct, generation, and vegetation — for us in the 21st century it should now be clear that reason is the most fundamental cause: that is, intelligent design.

In summary, Hume did not suggest that the analogy between natural complex order to human-designed complex order is invalid, as some try to do today: he merely argued that it was not certain, and that there was a better alternative. We can now see that his alternative fails completely because of what we have discovered at the very basis of life, and in particular the origin of life (an area about which even Darwin had little to say). We have not found magic, nor a gap that might need to be explained by magic. We have found rational mechanism; just the thing that most looks like our human designs. For more information (albeit not complete information!) see just about any cell or molecular biology textbook. Therefore, if Hume were true to the method and opinions expressed through Philo, he might still choose to be a skeptical atheist, but he would have to admit that intelligent design is, at very least, the best explanation we have. Welcome to the club, Dave!

Addendum: The Multiplication of Unseen Possibilities

Philo also offers a secondary argument but it is so awful you could justly consign it to a footnote. The argument is that if the universe is eternal, then anything could happen. But physicists have now concluded it is not eternal, first because of the law of entropy, and secondly because of the expansion of space (Big Bang theory), which implies a singularity in the past. We have also discovered that the universe is extraordinarily fine-tuned: just one more example of its deep rationality. It is easy to forget that historical materialists believed in an eternal universe (as well as vitalism). These days materialists are more likely to seek solace in an equally unprovable idea of a multiverse, but the defense is just the same: multiply the probabilistic resources so that anything could happen, including Boltzmann Brains and Flying Spaghetti Monsters. But I suspect this was little more satisfying then than now.  

Photo: Statue of David Hume, Edinburgh, Scotland, by Bandan [CC BY-SA 3.0], from Wikimedia Commons.