Bas van Frassen is probably the big name amongst philosophers of science involved in the defense of anti-realism. His particular brand is Constructive Empricism; quite simply his position, in his key text The Scientific Image (1980), requires withholding belief in any phenomena not counted amongst the actual and the observable. Truth, on any scientific inference, such as Inference to the Best Explanation (IBE), just is empirical adequacy about the observable world. Thus he withholds belief in unobservable phenomena like sub-atomic particles and DNA since they cannot be directly observed by unaided vision.
Now, being an ardent scientific realist I don't take van Fraassen's position to be particularly convincing. On the other hand I do want to highlight where he does make a very interesting and revealing point;
Unlike, say, Richard Swinburne, van Frassen does not believe that simplicity, being a non-empirical virtue, confers any degree of truthfulness on a scientific theory; or you might say that he does not believe that a more simpler theory, all else being equal, is necessarily an indication of truth. Van Fraassen holds that to believe simplicity is an ingredient of truth is to hold an unwarranted belief, since one has to assume simplicity before science is done. It is not gleamed from any particular piece of empirical information or any scientific experiment;
"Simplicity is quite an instructive case. It is obviously a criterion in theory choice, or at least a term in theory appraisal. For that reason, some writings on the subject of induction suggest that simple theories are more likely to be true. But it is surely absurd to think that the world is more likely to be simple than complicated (unless one has certain metaphysical or theological views not usually accepted as legitimate factors in scientific inference)." (Emphasis added, p.90)
The last phrase in parenthesis is what I wish to draw attention to. I don't believe van Fraassen is right that simplicity is not a criterion of truth. And I believe the majority of scientists and philosophers would concur. But I do believe his point is instructive that simplicity is not a virtue that can be deducted from any scientific theory or any experimental or empirical data. It is, rather, a philosophical and metaphysical (and even theological) assumption that is necessary to even do science successfully in the first place. One has to assume that the world has a particular meta-characteristic, or way in which it was created, in order for scientific theories to track the truth.
This seems to fly in the face of scientism and the absurd belief that science is a necessary condition for truth. It quite simply is not, and other disciplines like philosophy most surely have a role to play in making key definitions and clarifications about what science is and what are necessary assumptions for science to make in order to reveal truths about the world.
