This post is based on a 2008 paper by Christian philosophers Trent Dougherty and Ted Poston (D & P), who argue that two arguments for the existence of God, from physical fine tuning and biological design, are incompatible. [Paper available here – hat tip to Alexander Pruss at the Prosblogion, in a comment (along with related discussion) here] I have seen this kind of thing suggested elsewhere less rigorously, but in any case I think there is at least conceptual space for both. They may each fall foul of the empirical facts (I think it remains, to some extent, to be seen), but they may also be good arguments which are able to co-exist. It may perhaps be that neither is particularly strong as a probabilistic argument, and perhaps that one or both may be more properly considered non-inferential judgements involved in the formation of ‘basic beliefs’, akin to perception, as suggested by Plantinga in “Where the Conflict Really Lies” – I look forward to continued discussion of this question in the literature; and am happy to talk about it too.
My claim will be that some forms of probabilistic fine tuning and biological design arguments are compatible, and I sketch an example of integration along with reasons we might have for holding to both arguments. I argue against D & P’s claim that both arguments are dependent upon a common probability, with one requiring a high and the other a low value; more work is needed to make a full case, but I hope that I manage to call this central claim into question. Once I got into this, it turned out that many cans of worms had to be opened and the job has only really just been started; one day I may try to put some more of the lids back on.
[Images above are of the cosmic microwave background radiation and one of my favourite aspects of life, the different levels of packing in eukaryotic chromatin, i.e. the protein assemblages involved in compacting genetic material.]
The “Fine-Tuning argument” (FTA) moves from the apparent improbability of the initial conditions of the universe being as they were, to the truth of classical theism, i.e. the existence of God. The probability of the initial conditions being as they actually were is considered to be higher on classical theism than on, for instance, naturalism (in general, “not theism”), as the initial conditions obtaining can be considered a means to the end of something of value, “the kind of thing a good God would want to bring about” (D & P, 101), namely complex biological organisms (the ‘thing of value’ can, – and thanks to a conversation with Trent Dougherty last year, I think should be fleshed out in terms of moral agents, but organisms will do here). In other words, if the physical initial conditions observed are a priori improbable, but the truth of theism would raise the probability of this observation and the truth of naturalism would not, it provides evidence for theism over against naturalism. The biological design argument (BDA) focusses, as we might expect, on life itself, proceeding from the a priori improbability of life existing in our universe to (given the existence of life in our universe) the conclusion that God exists, on the basis that complex life is more likely on theism than on naturalism. For simplicity, I will assume that the BDA refers only to the origin of life rather than taking a position on how subsequent diversification was achieved. These arguments raise lots of interesting questions, some of which have been hinted at on this blog before, but for now I will stick to the question of whether they are compatible. Sustained discussion and defense of the FTA can be found by searching here and here.
The incompatibility can be stated for starters in this way: the FTA claims that the universe’s physical constants are set up by God for life, while the BDA rests on the claim that the physical constants were not sufficient to produce life i.e. one seems to claim that the constants were finely tuned for producing life, while the other presumes that they were not. P & D say “To isolate the issue at hand we need to consider whether [initial conditions] raises the probability of [biological organisms] apart from some other process that results in [biological organisms]” (101) and they go on to note that this isolation involves considering the probability of obtaining organisms given both the initial conditions and a lack of other processes directed towards forming said organisms. (Earlier stated as “P(B/C& ~P), the probability that biologically complex life [B] exists somewhere or other given C [the initial physical conditions] and that there are no other B directed processes, ~P”). I will call this probability “Z”. Note that what we see here is that if it is life-directed processes other than the physical constants (e.g. miraculous interventions of God) that do the work of producing life, then the FTA is undercut.
It is not clear that both the FTA and BDA are committed to taking into account the probability “Z”; specifically, the BDA requires a low value of Z, but a good FTA need not require a high Z, or even to take Z into account. Perhaps the constants referred to in the FTA should be considered as being set up for permitting rather than evolving (producing) life. The question that then arises is why the constants were not precise enough to prevent the need for further intervention (as envisaged in the BDA); i.e. can they really be said to be “fine-tuned” if further intervention is required? It may be that life is not the kind of thing that can be produced by the usual operation of physical law as we know it. If this is true, then intervention of some kind is required and the BDA goes through nicely. Salvaging the FTA requires an additional step to guarantee that on theism the initial conditions will be expected to be set up so as to permit life, rather than falling back on an intervention (associated with the “design” of the BDA) which sustains life somewhere in an otherwise entirely hostile universe. Pruss suggests [here] that God may have good reason to limit the number of miracles performed, but I think this negative consideration (avoid miracles) can be strengthened with plausible positive aims – notably that God has good reason to produce a universe that consistently obeys laws rather than a universe with a small atypical life-preserving pocket. In an orderly universe produced and sustained by a rational mind, physical conditions which allow for the existence of life in one area will, it is expected, hold throughout in a consistent manner, but need not be sufficient to produce life through the operation of natural processes.
A similar suggestion to mine, without the added justification seen here, is surveyed by D & P, who say in response to the idea that the BDA could be considered an added ‘fingerprint’ on top of the background data assumed in the FTA “this approach is not a reply to our criticisms but rather a capitulation and a choice of the BDA over the FTA.” (105). However, I think that given the value of consistent laws (such Eutaxiological arguments are made by Richard Swinburne), life-permitting constants ought to be expected on theism. The FTA is I think weakened a little in the shift from considering life-producing to life-permitting constants, but if that is where the evidence points, so be it. I am sympathetic to biological design arguments, but also open to the idea that life is ‘ingrained’ or inherent in natural law, and largely the product of natural processes (some of the work of Stephen Freeland on the origin of life and Simon Conway-Morris on evolutionary history are useful here). Such a view, as noted by D & P, while undercutting the classical BDA would tend to strengthen the FTA. Further empirical evidence on the capabilities of physical processes to produce complex autocatalytic networks of metabolism and information transfer is awaited.
D & P claim that “the foe of a stacked universe (i.e. a universe in which the initial conditions and laws make life almost certain) would need to argue that creation in many acts realizes a greater good than creation by a single act”. It is not at all clear that God’s only consideration is to maximise good in some abstract sense (this is perhaps worth exploring a lot more in future – I’d like to see whether a multi-faceted view of God’s intentions, in line with Scripture, could be incorporated into such arguments – theological reasoning concerning creation should be able to be incorporated into a theistic hypothesis), but as noted above, it is also not entirely clear that we should expect that life is the kind of thing that can be produced by merely physical processes – at least, not the kind of physical processes occurring in a world like this one, i.e. a world producing the goods found in this one. In addition, if the FTA is oriented towards the existence of something like ‘rational moral agents’ rather than merely ‘life’, then further constraints on the relevance of physical law to producing this end may come into play.
In conclusion, defending both a fine-tuning and biological design argument to the conclusion that God exists will take care in spelling out each, with reference to God’s likely intentions, the a priori probabilities, and empirical evidence from the sciences; however I believe both arguments are promising avenues in producing defences of the rationality of theism and they need not be incompatible. Even if the empirical evidence is thought to be strongly supportive, neither (it should be obvious) is a knock-down proof; but in the absence of any opposite such proof for naturalism, the theist has little to worry about from a little humility in stating his/her case.