The classical debate here is between realists and idealists. It is metaphysical in nature; i. e. , it is about the nature of reality or, at least, about what our fundamental concepts imply about the nature of reality. Realism is the view that the world exists apart from our perception of it. Idealism says that the world is, in some sense, mind-dependent. Few philosophers of science subscribe to idealism; however, many of them subscribe to something related which is sometimes called “conventionalism.
In the philosophy of science, the difference between realism and conventionalism is as follows. Realists regard scientific theories as attempts to give us a literally true depiction of reality. For a realist, accepting a scientific theory entails believing that the things mentioned in the theory- e. g. , atoms, species, genes, etc. .- actually exist. Conventionalists regard scientific theories as useful linguistic conventions which can be fully accepted for scientific purposes without ecessarily believing that they are literally true.
Argument for anti-realism Conventionalists are not necessarily idealists, but many tend to be anti-realists. In general, anti-realists are skeptical about the existence of things that are not accessible to direct experience, but common-sensical about the existence of things that can be seen with the naked eye. The appeal of anti-realism. lies in the adage that you shouldn’t believe anything you can’t see or touch. It is also supported by a principle known as Ockham’s Razor which basically counsels us to keep things simple; don’t make any unnecessary assumptions.
For the conventionalist, the reality of observable entities is a necessary assumption, but the reality of theoretical entities is an unnecessary one. Argument for realism The realist has two basic responses to this way of thinking. First, the reality of theoretical entities is unnecessary only if you arbitrarily limit the kinds of questions you are willing to ask. The conventionalist thinks of theories as compact ways of describing an infinitely large set of possible observations (just like a mathematical function [say, y = x2+ 2] is a compact ways of describing an infinitely large set of ordered pairs of numbers [….. ,,, ….. ]); but, claims the realist, unlike mathematical functions, scientific theories do not merely describe, they also explain.
The theory of the atom, for example, does not merely describe the macroscopic behavior of solids, liquids, and gases under a variety of conditions; it explains why they behave in the way that they do. Since, according to the realist, it is impossible for one thing to explain another if the first thing does not even exist, the realist concludes that the conventionalist is simply choosing to ignore the explanatory dimension of science.
Conventionalists have responded to this charge in different ways: some simply deny that science explains anything; others develop theories of explanation that do not require us to accept the reality of theoretical entities. The realist’s second argument against anti-realism consists in pointing out that the kinds of things that most anti-realists regard as observable are themselves theoretical entities.
Three-dimensional physical objects, like pencils, pigeons, and parachutes are not directly observed in any epistemologically significant sense. They are theoretical entities that allow us to make sense of our subjective sense impressions. So, for example, when I say that I see a pencil, in fact I am unconsciously positing the existence of this three-dimensional object to account for a certain persistent set of two dimensional impressions of shape and color which also coincide in my mind with other sensations of weight and texture.
Although this argument is meant to establish that theoretical entities like protons and electrons are no more theoretical, and therefore no less real, than medium-size physical objects, it also establishes that medium-size physical objects are no more real and no less theoretical than protons and electrons. In other words, this way of attacking conventionalism is just as much an argument for the unreality of observable objects (idealism) as for the reality of unobservable objects (realism).