An Empiricist Criterion of Meaning

When we use scientific propositions, in order to describe phenomena and organize our knowledge about the physical world, we use terms that do not refer to observable entities. So as to explain chemical reactions, we would refer to atoms or electrons, that we cannot see directly. And even such a familiar concept as the one of mass is not observable, in the sense that it cannot be in all cases, in all experimental contexts, defined only by observable concepts or observations. Consequently, we can worry about the role of such theoretical terms, and wonder what their empirical meaning is, or at least whether it is possible to find a way to express such an empirical meaning. Empiricists may ask that theoretical terms should be used only if they are empirically meaningful. The question I wish to deal with is one of knowing what theoretical terms refer to, and to what extent we are committed to the existence of theoretical entities by adopting a theory. I wish to show that it is possible to characterize the empirical meaning of theoretical terms and address the worry of their ontological commitment.