I reject both (a) inevitabilism about the historical development of the sciences and (b) what Ian Hacking calls the "put up or shut up" argument against those who make contingentist claims. Each position is guilty of a lack of humility about our epistemic capacities.

Arthur Lovejoy’s history of unit-ideas and the history of concepts are often criticized for being historically insensitive forms of history-writing. Critics claim that one cannot find invariable ideas or concepts in several contexts or times in history without resorting to some distortion. One popular reaction is to reject the history of ideas and concepts altogether, and take linguistic entities as the main theoretical units. Another reaction is to try to make ideas or concepts context-sensitive and to see their histories as (...) dynamic processes of transformation. The main argument in this paper is that we cannot abandon ideas or concepts as theoretical notions if we want to write an intelligible history of thought. They are needed for the categorization and classification of thinking, and in communication with contemporaries. Further, the criterion needed to subsume historical concepts under a general concept cannot be determined merely on the basis of their family resemblances, which allows variation without an end, since talk of the same concepts implies that they share something in common. I suggest that a concept in history should be seen to be composed of two components: the core of a concept and the margin of a concept. On the basis of this, we can develop a vocabulary for talking about conceptual changes. The main idea is that conceptual continuity requires the stability of the core of the concept, but not necessarily that of the margin, which is something that enables a description of context-specific features. If the core changes, we ought to see it as a conceptual replacement. (shrink)

The distinction between essential versus accidental properties has been characterized in various ways, but it is currently most commonly understood in modal terms: an essential property of an object is a property that it must have, while an accidental property of an object is one that it happens to have but that it could lack. Let’s call this the basic modal characterization, where a modal characterization of a notion is one that explains the notion in terms of necessity/possibility. In the (...) characterization just given of the distinction between essential and accidental properties, the use of the word “must” reflects the fact that necessity is invoked, while the use of the word “could” reflects that possibility is invoked. The notions of necessity and possibility are interdefinable: to say that something is necessary is to say that its negation is not possible; to say that something is possible is to say that its negation is not necessary; to say that an object must have a certain property is to say that it could not lack it; and to say that an object could have a certain property is to say that it is not the case that it must lack it. (shrink)