It is a mistake to believe that the distinctions are congruent, that observational terms apply to observable things and theoretical terms to unobservable things.
"But we still need to pin down exactly what observable things about a teacher matter for their effects on students".
They draw the mind too far away from physical and observable things, and make it unfit to study them.
Scientific realists, by contrast, regard theories as attempts to describe reality even beyond the realm of observable things and regularities, so that theories can be regarded as statements having a truth value.
His position, constructive empiricism, holds that the aim of science is empirical adequacy, where 'a theory is empirically adequate exactly if what it says about the observable things and events in the world, is true' (p. 12; p. 64 gives a more technical definition in terms of the embedding of observable structures in scientific models).
What matters for our purposes is not Carnap's sense of a commensurability between a metaphysical thesis about reality and a practical decision to speak only about observable things, but rather that he thinks he can explain how the illusion of meaningfulness arises for the metaphysical theses he declares "devoid of cognitive content".
Yet the pre-established harmony was at least consistent with Leibniz's claim that substances do not interact with one another and that what we call "causal interaction" does not involve a flow of power or force, but merely a regular sequence of changes in two observable things, in the case of mind and body, the experiences of perception and appetition and states of the sensory organs (G 4 76 7).
Each man in their way remains tethered in concept to the external world of observable things and places; each articulates an abiding affection for the idea of layering as both a practical and metaphysical activity.
Churchland concludes that the distinction between things that are unobserved but observable, and things that are unobservable, "is only very feebly principled and is wholly inadequate to bear the great weight that van Fraassen puts on it" (Churchland 1985, 40).
In particular, it has been held that the theoretical entities of science are definable in terms of observable physical things, so that scientific laws are equivalent to combinations of observation reports.
