The Duhem-Quine thesis, when simplified, explains how a given set of facts can produce more than one apparently true conclusion: essentially, different background assumptions lead to different outcomes. A related concept is known as underdetermination: that a given set of evidence can be explained by more than one — potentially conflicting — theory.
One pertinent example: most biologists look at the diversity of species and say that evolution by natural selection (with at least a hint of randomness) is the best explanation, whereas believers in Intelligent Design see God’s hand at work. Given a certain view of available evidence, both explanations might be possible (especially if an all-powerful God simply creates everything, including fossils, in situ). So how can we resolve this problem whereby a set of facts can justifiably be argued to support multiple potential theories?
One approach is to limit ourselves to certain kinds of theories as potential explanations: science tends to allow for only theories that are potentially testable, verifiable, falsifiable, etc. Most scientists say, despite arguments to the contrary, that the existence of a divine presence guiding evolution is simply out of bounds for scientific inquiry. It’s a matter for faith, not empirical inquiry; it’s religion, not science.
Of course, as John Hedley Brooke points out, the meaning of the terms “science” and “religion” has changed over time, and “it is more appropriate to speak of ‘sciences’ and ‘religions.’ When we do, any simple dichotomy loses its rigidity” (297). Thus, for example, the term “science” once included any organized body of knowledge (which would have included theology), though now it has a more specific meaning. “Religion,” too, only emerged as a useful term when “comparative approaches were needed for the analysis of different cultures … in the Enlightenment” (297). Still, the distinction is at least analytically useful, and however historically suspect, it is relied upon by most writers today.
Another approach to managing the (potentially illusory) conflict between science and religion is favored by Owen Gingerich, astronomer and author of God’s Universe. He turns to Aristotle to help differentiate two kinds of explanation put forth by science and religion. Put in Aristotelean terms, faith can be seen as a search for “final” causes, while traditional science could be said to stick instead to “efficient” causes. There is thus no conflict between science and religion, and no worries about underdetermination traceable to this conflict, since each explains different things.
Gingerich looks to Blaise Pascal’s notion that “some things only the heart knows” to explain this idea and justify his belief in (small case) “intelligent design.” Since science cannot know or determine certain truths (final causes, in Aristotelian terms), we can freely posit a (distant) intelligent designer without worrying about stepping on scientific concepts of proof. In essence, two truths become simultaneously possible, because they occupy different domains of truth. Intelligent Design (not Creationism, and not the lower-case “intelligent design” of Gingerich), on the other hand, believes that science can be used to access the truth of an intelligent creator, and that this search is scientific.
Creationism, on the other hand, tends to reject science more firmly (but not, interestingly, technology). It inherits from a tradition of the literal exegesis of scripture used, for example, in the 16th century. Of course, today’s Biblical literalism is only related to, but not identical with, 16th-century exegesis. After all, bringing in a passage of scripture today is no longer a means of shutting down debate.
So how did followers of Copernicus in the 16th century deal with the issue of causation, given the power of Biblical exegesis at the time? They did so by arguing that scripture itself underdetermines potential explanations — even if it can shut down blatantly conflicting theories. Relatedly, Johannes Kepler tried an accommodation approach with literalism. He maintained that God, in order to be understood by normal people, caused the Bible to be written in ordinary language. This is why there are no discussions of epicycles in the Bible. The Bible thus accommodates ordinary folk with a different, non-scientific vocabulary that, if read correctly, does not conflict with science.
Of course, many — most? — of today’s scientists simply step outside of the argument, and point to materialist, naturalistic explanations as being all that is necessary for science — certainly they are the only valid scientific theories — even in religion can provide different kinds of explanations (which may or may not be important to the scientists personally). And how do they often justify this? Because these explanations work. Certainly this is the approach taken by most engineers and developers of technology, and perhaps, then, this is why Christian fundamentalists and Muslims have no trouble reconciling their faith with structural engineering or software development. They focus on the science that works in a materialist sense, and not the science that raises uncomfortable questions (evolutionary biology, for instance).
Alternatively, if this approach to dealing with underdetermination is dissatisfying, then there is always the choice to go to absolute knowledge, as David Bloor reminds us: if the Pope says it’s true, then no doubt exists, and we escape the problem of underdetermination and uncertainty. The Catholic Pope is not the only option, of course. Islam, despite its lack of central authorities, also relies on the authority of absolute knowledge — revelation from the Qur’an — to solve the problem of underdetermination. Medieval Islam appears to have successfully negotiated any potential conflict between Qur’anic knowledge and scientific knowledge. Modern Islam, on the other hand, is arguably still searching for the proper balance. Modern evangelical Christianity, too, seeks a new balance between science and faith.