At the ARS session of the APA Pacific Division Meeting in April 2012, Travis Norsen presented a paper “Scientific Cumulativity and Conceptual Change: The Case of ‘Tempurature’.” Dr. Norsen* is a visiting Professor at Smith College. Comments were delivered by James Lennox* and by Hasok Chang.* I shall discuss the Norsen paper and the comments on it shortly. In the present post, I’ll set out the pertinent Randian background.
Ayn Rand thought of concepts as designating items in kinds. A concept does not consist of only the essential characteristic(s) of the kind, which is objective, though a function of the present stage of human understanding of the kind. A concept includes all the characteristics of the kind, known or yet to be discovered (ITOE 27, 65–66; cf. App. 147). Right definition of a concept derives from right formation of the concept, and although the definition does not mention all the characteristics of instances falling under the concept, it implies them (42). The scientist’s grasp of complex abstractions is an integration of a long conceptual chain, and this is a contextual process (43). Discoveries can bring it about that an earlier definition no longer distinguishes the kind from others. A definition can then be expanded by acknowledging a different characteristic as essential in place of the earlier essential characteristic of the kind (47). (See also Peikoff 1967, 94–106* in ITOE, 2nd edition, and see OPAR 96–105.)
It is easy to assume that when the definition changes, the concept changes.
No, the context of your knowledge changes. When you know more, you select a different essential characteristic by which to define the object, because you now have to differentiate it more precisely. Your knowledge has expanded, but the concept doesn’t change. / The similarities and differences according to which you originally formed the concept still remain. So you haven’t changed your concept. Your old distinction remains the same; the concept refers to the same entity [existent]. Only now you know more, your field of knowledge is wider, and therefore you have to define your concept by a different essential characteristic.
I was falling into the old trap of thinking that the concept refers to the—
To the definition only.
Or only to the similarities and differences known at a given time.
Yes. But if you keep in mind that your concept refers to referents, to things, you will see that it doesn’t change, but your knowledge changes. (ITOE App. 233)
The meaning isn’t just the essential characteristic.
The essential characteristic and lesser characteristics also. But . . . if one man has observed more characteristics than another, he knows more characteristics than another, he knows more about the referents of the concept, which doesn’t mean he understands the meaning of the concept better.
The meaning of the concept is the entities which it integrates, and you know the meaning when you know which entities it integrates.
If you discover why water boils, you will know something more and will be able to do more things with water than the primitive man who knows only that if he holds it over fire a certain length of time it will boil. By discovering such issues as temperature and molecular structure, you have made yourself infinitely more capable of dealing with water and using it for your purposes than the primitive man who only made the first observation. (301)
“It is perhaps clear already from what has been said about concepts and definitions . . . that [Rand] would reject both the traditional Fregean view that ‘meaning determines reference’ and the more recent ‘direct reference’ theories” (On Ayn Rand  – A. Gotthelf).
“Reference and Necessity: A Rand-Kripke Synthesis” by R. T. Long (a review of G. M. Browne’s Necessary Factual Truth  in JARS, Fall 2005).
“Concepts, Context, and the Advance of Science” by J. G. Lennox and the comments thereon in Concepts and Their Role in Knowledge – Reflections on Objectivist Epistemology (2013).