This is part four in a series taken from Louis' paper (downloadable here), which addresses common Christian misconceptions about the nature of science and its relationship to God's involvement in our world. Links to the first three parts are located on the side bar to the right.
Natural Theology and Evolutionary Metaphors
Pure chance, absolutely free but blind, is at the very root of the stupendous edifice of evolution…The ancient covenant is in pieces; man at last knows that he is alone in the unfeeling immensity of the universe, out of which he only emerged by chance.
- Jacques Monod,
"Chance and Necessity: An Essay on the Natural Philosophy of Modern Biology", Knopf (1972)
There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.
- Charles Darwin, "Origin of Species" (1859)
The main message of the previous section is that Christians need to be very careful when trying to derive theological truths from the mechanisms of nature. But it is not all doom and gloom for natural theology. Alister McGrath, for example, has recently called for a renewed approach that is more sensitive to the critiques of Newman, Barth, and others:
Contrary to the Enlightenment’s aspirations for a universal natural theology, based on common human reason and experience of nature, we hold that a Christian natural theology is grounded in and informed by a characteristic Christian theological foundation. A Christian understanding of nature is the intellectual prerequisite for a natural theology which discloses the Christian God.1
There is no “view from nowhere”. So if we start from Christian presuppositions, does this make more sense of the world than other vantage points do? Does what we observe within the natural order resonate with the core themes of the Christian vision of God? This approach is potentially much more fruitful, and McGrath makes a very impressive start with his recent Gifford lectures2, which include a gentle attempt to look at biological evolution, and explore a fascinating connection to Augustinian notions of primordial actuality and emergent possibility.
Nevertheless, we probably don’t understand enough about biology to make much progress towards a detailed natural theology. That doesn’t mean that many Christians and Naturalists haven’t tried. Most popular attempts tend to flounder into some version of either God of the gaps or atheism of the gaps. One of the biggest problems is the reliance on metaphors that anthropomorphize natural processes (including evolution), and/or introduce all kinds of morally-freighted terminology.
And before we can even speak of metaphors, it is necessary to delineate what we mean by evolution. As many authors have pointed out, the word evolution has many meanings. Here is a simple taxonomy:
- Evolution as natural history: The earth is old and the kinds of organisms that populate our world have changed over time.
- Evolution as a mechanism: A combination of variation and natural selection helps explain the structure of the observed change over time in natural history.
- Evolution as a worldview: Evolution as a way of seeing the world and extracting meaning from it. See e.g. George Gaylord Simpson’s famous quote: Man is the result of a purposeless and materialistic process that did not have him in mind. He was not planned. He is a state of matter, a form of life, a sort of animal, and a species of the Order Primates, akin nearly or remotely to all of life and indeed to all that is material.3
Christians rightly reject definition 3. Almost all the hermeneutical tension with Scripture arises from natural history (what about Adam, the fall etc…). But as critically important as these theological issues are, I won’t treat that topic here. Nevertheless, much Christian resistance to evolution also arises from definition 2. That is the main sense in which I will be using the word when examining the following metaphors:
Random or Stochastic?
Monte Carlo algorithms that rely on random sampling are routinely used to calculate everything from the value of your stock portfolio to the airflow around a rocket returning into the atmosphere. They are part of a wider class of so-called stochastic methods. It is not hard to demonstrate that for many high-dimensional problems such stochastic methods are the most efficient solution methods available. If you view evolution as an optimization problem in a very high dimensional space, then the most efficient way to solve this problem would probably be by stochastic methods. From that perspective it is not surprising that, if God wanted a universe where biological complexity emerged through the regular ways he sustains the universe, he would employ a stochastic algorithm to achieve this goal. The problem is that the word “random variation” has all kinds of other value-laden connotations. If instead we used the technical term “stochastic variation” it could clear up a lot of confusion.
In this context it is important to emphasize that although Monte-Carlo algorithms employ stochastic methods to generate variation, they are not random in their outcomes. They converge on the desired solution only if you chose the right kinds of variation and the right kind of selection. One could, in fact, aptly employ the metaphor “survival of the fittest” to the describe the way a Monte Carlo program selects between the stochastically generated variations to solve a problem, say, in engineering, but hopefully the temptation to extract further meaning from this metaphor would be curtailed.
Self-assembly – shaking a box of Lego bricks and out comes a fully formed train?
Your body is full of intricate machinery. If you were to happen across a scaled up version of one of these machines, you’d assume that it was made by an assembly line or some other much more complex system. But in biology there are no such factories. Instead composite objects self-assemble – they make themselves. It is a little bit like having special Lego blocks. You put them in a box, shake it, and out comes a fully formed train. I’m sure most people would agree that such Lego bricks would be much more impressive than the standard ones. This self-assembly metaphor nicely captures what happens in evolution. Rather than making things fully formed, God could have used a process by which things “make themselves”.
From my lab: a picture of the self-assembly of a model T=1 icosahedral virus. Time increases from (a) –> (d). Each virus capsid is made up of 12 pentagonal bipyramids. If the interactions between the particles are designed correctly, they can be placed at random initial positions, and then move around randomly, but they nevertheless will always end up as well-formed icosahedra. The correct design depends more on the topology of the search space than it relies on the types of random (stochastic) steps available. See I. G. Johnston, A. A. Louis and J. P.K. Doye, “Modelling the Self-Assembly of Virus Capsids “, J. Phys.: Condensed Matter, 22 ,104101 (2010) for more details.
Genes as blueprints or as networks of switches?
One of the surprises that came out of the human genome project was how few genes (protein coding stretches of DNA) humans have — around 23,000, not that different compared to the fruit fly with 14,000, and quite a bit less than rice, with 51,000. Traditionally the metaphor for genes was something more akin to a blue-print, — the “standard dogma” of Francis Crick: each gene codes for one mRNA which codes for one protein — but now we realize that many are better viewed as switches or volume knobs. Moreover, one gene can have multiple effects. Complexity arises not so much from the genes themselves as from the connections between them. These network properties are currently an enormously rich topic of research. For example, the way the network is connected can dramatically affect the interplay between robustness to mutation and evolvability (the ability of a system to generate heritable phenotypic novelty). The single gene <—> single property blueprint metaphor is outdated.
Part of the transcriptional network of an E. Coli bacterium. The red dots denote proteins, and the black arrows show how the proteins are regulated by one another. Source: U. Alon.
We will look at a few more of these metaphors in the next post.
1. A.E. McGrath, The Open Secret: A New Vision for Natural Theology, Oxford: Blackwell (2008), p4
2. A.W. McGrath, A Fine-Tuned Universe: Science, Theology, and the Quest for God (2009)
3. George Gaylord Simpson, The Meaning of Evolution, Yale University Press, (1967), p. 345.