Mouse asked:
Can you please explain the difference between scientific realism and scientific anti-realism as viewpoints in the philosophy of science? Especially, how do scientific realists and scientific anti-realists differ in their views of 1) scientific facts, 2) scientific hypotheses, 3) scientific laws and 4) scientific theories? Also, can you please comment on how they differ in their views of atoms, electrons and quarks? Would a scientific anti-realists deny the existence of atoms, electrons and quarks?
Answer by Jürgen Lawrenz
Strictly speaking, you should consult a scientific Q&A website for this question. However, as its philosophical aspect interests me, I’ll give a response in those terms, while being mindful of the little adage of the bull in the china shop.
Scientific anti-realism is the doctrine which combats the notion that unobservables are ‘real’ things or events in the ‘real’ world. It lays stress on the possibility that instrumental results from experiments may not demonstrate existence conclusively. There is much to be said for this, especially in situations where the instrument itself has a prejudicial influence on the results, as in the realm of the quantum. We dive in and find ludicrous nomenclatures like ‘quarks’ and their ‘colours’ and ‘flavours’ being traded as if they were equivalent to the candies they gave us in kindergarten. To all this John Wheeler gave a consummate answer with his proposition of an “observer-created reality”, which means that the observer must take responsibility for interpreting his/ her findings and stop pretending they are objective facts. You might also remember Eugene Wigner’s frustration with the observation of quantum collapse experiments, when each time he looked, a different ‘fact’ stared him in the face. We seem to have found ways to ‘get around’ these irritations more recently, but many people would say that this is still instrumentalism, not objective reality.
The philosophical issue here is, that (cautiously phrased) we cannot truly bridge the discrepancy between outcomes of an experiment that has a tangible effect in the macroscopic world and the theoretical outcomes of experiments which leave only ambiguous traces like pointer readings or smears on a wall. If you take a sledge-hammer to an ornately wrought glass urn, you will not be able to reconstruct the object from the pulverised remains. But this is what a great deal of subatomic research purports to effect. You see the problem.
As for atoms, there is no need to deny them. They register willingly on spectrometers to support the conviction that they are physical objects. It is different with electrons which seem to be ‘states of energy’ of an atom and vulnerable to misconception as particulate ‘entities’. What actually happens inside an atom during fusion or fission cannot be made visible, although the outcome is highly visible and destructive. Divisibility in this case encourages the belief that an atom is an entity made of parts; and that the parts are themselves compounded of parts (hence the term ‘particles’); and so it goes down the ladder until we get either to the point where theory has no decimals left with which to resolve the difference between ‘space’ and ‘object’ or else just slides into infinite regress. Indeed a number of such routines — especially on computers whose rounding off routines are not positively knowable — rely on ‘re-normalisation’, a sophisticated term for the more common word ‘fudging’.
An anti-realist would certainly deny the reality of all the creatures of this zoo, and one could easily evince sympathy with their point of view. None other than Werner Heisenberg complained in a famous lecture that the questions “what is it made of?” and “are they divisible?” in relation to particles are wrong questions based on bad philosophy, and he wasn’t an anti-realist. Barrow and Tipler wrote a chapter, ‘Are there any laws of physics?’ (in their book The Anthropic Cosmological Principle), in which they claim that the laws of physics exist only in the minds of physicists which they then plaster over phenomena because they expect to see those laws being enacted. For my person, I feel that the quip “laws are made to be broken” suffers no exceptions. The laws of science are all man-made, and the number of these laws that have toppled over the last two centuries would fill a sizeable garbage bin.
No disrespect to the brilliant scientists working those fields is intended with these remarks. Moreover, I doubt that realists and anti-realists are encamped in mutually hostile quarters and never talk to each other. But I feel (very strongly) that Heisenberg’s point is relevant and that science going alone without philosophy is like a horse and carriage that lost the carriage.
There you have it. Inadequate, but hopefully somewhat illuminating.
Ask a Philosopher 
Nice answer.