We think of scientists as creating models to explain reality. The effectiveness of these models, be it Einstein’s Theory of Relativity or Darwin’s Theory of Evolution, makes us believe in them. Many scientists and philosophers argue that to take these models as being effective explanations is to take them as being true. But this idea of explanation is as superfluous to theories of science as an orgasm is to procreation, argues Bas van Fraassen.

When physicists present to each other at conferences they are all about mathematical models. The participants are deeply immersed in the abstract mathematical modelling. When on the other hand they present to the public it sounds all very understandable, about particles, waves, fields, strings, quantum leaps and gravity. That is very helpful for mobilizing the imagination and an intuitive grasp on how phenomena or experiments look through theory-tinted glasses. But typically, it is also told as the one true story of the universe, its furniture and its workings. Is that how we should take it?

When physicists evaluate new models, hypotheses or theories they are also immersed in theory. It goes like this: the theory says “I’ve designed a test you can do, a test based on how I represent the phenomena, and what I count as measurement procedures. Take me up on it, see if I pass! Put me to the question, bring it on!” And it is great news when the measurement results come in and the theory is borne out. That is empirical support for the theory. What precisely should we take away from this, seeing here the scientists’ own criteria of success in practice?

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When it comes to general issues of science philosophers still divide roughly into empiricists and realists.

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During the past hundred years or so philosophers of science have become more and more compartmentalized and specialized, but when it comes to general issues of science philosophers still divide roughly into empiricists and realists. 

The scientific realists react to what I described with a story about what to believe. The empirical support gives us good reason to accept the theory, we all agree. They continue with: good reasons to accept a theory are good reasons to believe that the theory is true and that the things it talks about, observable or not, are really real. And the aim of science, they submit, is to give us stories, true in all respects, about what there is.

SUGGESTED READING Reality is not revealed by quantum mechanics By Peter West

It is only rational, they argue, to believe that our best current scientific theories are true. That was not the attitude of Darwin, Einstein, or Bohr. Should it be ours? To be effective, working scientists are indeed immersed in the world picture within which they work, accepting the "background" sciences, taking for granted the success of their predecessors on which they build. But how much belief is involved in acceptance and in taking for granted?

Empiricists see the same scientific practices differently from the realists. When the theory offers itself to be put to the question it shows how, if its models are adequate, the phenomena can be accommodated in those models. Take, for example, the various experiments that were inspired by the Einstein-Podolsky paradox. The measurement results show correlations between distant events which cannot find a place in the models of classical physics, but can be very well represented within quantum mechanics’ models.