Hilary Putnam (1926-) was, like Hempel and Salmon, a student of Reichenbach, but his work is less concentrated on the philosophy of science than is theirs.

Notice that Putnam refers to Carnap’s view of theories as the “received view,” a phrase that Salmon used to describe Hempel’s view of explanation. Both Putnam and Salmon are members of a generation who developed criticisms of the picture of science developed by logical positivists like Hempel and Carnap.

Putnam’s criticisms focus on one aspect of Carnap’s view, its association with a distinction between the observational and non-observational. This issue is tied historically to the question whether it is laws or models that are most important aspect of theories. Positivists were uncomfortable with thinking of models as most central because it seemed to loosen the ties between scientific theories and empirical evidence and made theories seem closer to non-empirical “metaphysics.” From this point of view, the central problem in an account of scientific theories is to show how their special vocabulary can be linked to observations, and much of Carnap’s work—especially, the work Putnam refers to—seems designed to do this.

The issue of the relation of theoretical terms to observation is not Carnap’s only concern in what you have read, but it is certainly present. You should look back at what Carnap says about the theoretical/observational distinction (especially at the beginning of the selection, pp. 316-319) so you can have it in mind as you consider Putnam’s attack on the distinction.