What is Theoretical Pluralism?
Theoretical pluralism says that a scientific theory is nothing more than a representation of Nature. It is not possible to capture the essence of Nature by means of scientific discoveries, and such ultimate science (knowledge) is not attainable. As Boltzmann says, two questions fall out of human understanding: why we are here, and why we are in the present, and neither scientists not philosopher are in a position to answer such questions.
Discovering the Theory?
In the light of theoretical pluralism, it is possible to clarify some vague points in the terminology of philosophy of science. The laws of Nature are totally different from the laws of physics, as the former deal with the essence of existence, but the latter is created by the theorist’s creativity. In other words, theorists (generally scientists and philosophers) do not discover a new theory (revealing the laws of Nature, but they invent a theory to explain Nature.
In this direction, a scientific theory will not be complete or definitively true, and even an apparently successful theory may be replaced by a better one. On the other hand, different theories (even opposite ones) can successfully explain a single natural phenomenon. A theory is basically a creative invention of the theorist who proposed it from a purely personal perspective, metaphysical presuppositions, theoretical options, preferences for a certain type of mathematical language, and the dismissal of some observational data; thus, it is not possible to find a theory formulated from the mere observation of natural phenomena.
As quoted in Populare Schriften (1905), Boltmann states, “Hertz makes physicists properly aware of something philosophers had no doubt long since stated, namely that no theory can be objective, actually coinciding with nature, but rather that each theory is only a mental picture of phenomena, related to them as sign is to designatum. From this it follows that it cannot be our task to find an absolutely correct theory but rather a picture that is, as simple as possible and that represents phenomena as accurately as possible.”
One might even conceive of two quite different theories both equally simple and equally congruent with phenomena, which therefore in spite of their difference are equally correct. The assertion that a given theory is the only correct one can only express our subjective conviction that there could not be another equally simple and fitting image.
Since there is no ultimate theory, a completely true one, it is necessary to find good theories. The aim of a theory is to explain a natural phenomenon, thus, a good theory is the one which is simple but effective. Consequently, the duty of scientists is to find better theories in accordance with their applicability, not to find true and ultimate theories.