Writing for the Chronicle of Higher Education, Princeton history professor Michael D. Gordin has an article titled, “Separating the Pseudo from Science.” He offers some clear thinking on the question of “What constitutes science?” and on the inappropriateness of using terms like “pseudoscience.” Gordin writes:

The renowned philosopher Karl Popper coined the term “demarcation problem” to describe the quest to distinguish science from pseudoscience. He also proposed a solution. As Popper argued in a 1953 lecture, “The criterion of the scientific status of a theory is its falsifiability.” In other words, if a theory articulates which empirical conditions would invalidate it, then the theory is scientific; if it doesn’t, it’s pseudoscience.

That seems clear enough. Unfortunately, it doesn’t work. Epistemologists present several challenges to Popper’s argument. First, how would you know when a theory has been falsified? Suppose you are testing a particular claim using a mass spectrometer, and you get a disagreeing result. The theory might be falsified, or your mass spectrometer could be on the fritz. Scientists do not actually troll the literature with a falsifiability detector, knocking out erroneous claims right and left. Rather, they consider their instruments, other possible explanations, alternative data sets, and so on. Rendering a theory false is a lot more complicated than Popper imagined — and thus determining what is, in principle, falsifiable is fairly muddled.

The second problem is that Popper fails to demarcate in the right place. Creationism, for example, makes a series of falsifiable claims about radioactive dating, rates of erosion, and so on, while the more “historical” sciences, like geology and astronomy, pose theories that are more explanatory narratives than up-or-down (and therefore falsifiable) protocol statements of empirical bullet points. Any criterion had better at least replicate our common-sense notion of “science,” and so far no clear criterion has been able to do so. No wonder most philosophers have given up on the task. As the prominent philosopher of science Larry Laudan put it 30 years ago: “If we would stand up and be counted on the side of reason, we ought to drop terms like ‘pseudoscience’ and ‘unscientific’ from our vocabulary; they are just hollow phrases that do only emotive work for us.” Demarcation is distinctly out of fashion among philosophers today.

Intelligent design (ID), of course, doesn’t challenge established estimates of the age of the earth. It makes very different claims than does creationism. Nonetheless, ID does make testable and falsifiable claims — and by any reasonable definition of “scientific theory,” ID qualifies. Despite that fact, ID is subjected to constant accusations that it’s “untestable,” and therefore not science. In fact, the U.S. National Academy of Sciences (NAS) has officially declared, “Intelligent design is not a scientific concept because it cannot be empirically tested” (Science, Evolution, and Creationism (National Academy Press, 2008), p. 42).

But the NAS is entirely confused on this point. We see this confusion two pages earlier in the same document where the NAS writes that “the claims of intelligent design creationists are disproven by the findings of modern biology” (p. 40). So according to the NAS, ID “cannot be empirically tested,” but its claims have been “disproven by the findings of modern biology.” Surely both statements cannot be true.

If “[d]emarcation is distinctly out of fashion among philosophers today,” folks at the NAS (or philosophers like Robert Pennock who testified at the Dover trial) didn’t get that memo. It also seems that clear thinking on demarcation is distinctly out of fashion at the NAS.