The secular debate between realism and nominalism (or anti-realism, its now preferred name), has been expressed in a few new theories of the so-called analytical philosophy, whose origin dates from the early twentieth century, with Gottlob Frege, Bertrand Russell, Ludwig Wittgenstein, the Circle of Vienna and several philosophers of the last fifty years, especially in the Anglo-Saxon world.
Currently, the two camps, realist and anti-realist, agree on one thing: science works. But although this is considered an incontrovertible fact, very divergent positions are posed to explain it.
As it has always happened throughout history, neither of the two fields is united. Both realism and anti-realism are divided into two branches, at the least.
Let us start by describing the realist position:
Scientific theories arise as a consequence of observation, but not just that. In scientific research, a cumulative effect takes place. Thus, Newton's theory explained the movements of celestial bodies, but it also made correct predictions, such as the discovery of Neptune. The trouble is, from time to time we get previously unknown new observations that the standard theory cannot explain, as in the case of the precession of the orbit of Mercury. In this case it was necessary to conclude that the theory was not correct.
Let's look at another example: At the beginning of the 19th century, John Dalton proposed the atomic theory to explain chemical reactions. For a long time (practically the entire 19th century), the existence of the atom was simply considered as a useful hypothesis. Ernst Mach, for example, denied the reality of atoms. However, since the beginning of the 20th century practically all physicists think that atoms really exist, as this hypothesis has given rise to countless technological advances.
In this context, realist philosophers can be divided into two currents:
- Realism of truth, which holds that scientific theories work because they are true. We can affirm that atoms exist, because we have overwhelming evidence that confirms it.
- Realism of entities, which states that, although entities such as atoms exist, our theories about them may be wrong. Perhaps the properties that we attribute to those entities are not exact; possibly later research will force us to modify them.
In the opposite side, anti-realist philosophers are also divided into two branches:
- Those who assert that we have no reason to affirm that entities exist (atoms, electrons, genes...)
- Those who assert that we have reasons to affirm that entities do not exist.
Note that the four positions (two realist and two anti-realist) make a scale that goes from almost-Platonic realism to total anti-realism, much like the debate between realists and nominalists in the Middle Ages. We could say that history tends to repeat itself, although not exactly in the same way. We’ll get back to this in the next post.