Abstract
In a Fregean case, a rational subject can believe that a certain entity possesses property F, and, at the same time, refuse to believe that this same entity possesses property F. It follows that concepts, the constituents of thoughts, are not individualized by their reference. Frege's argument in favor of this conclusion can be summed up as follows: concepts cannot be individualized by their reference, for if they could, the identity of reference would, in Fregean cases, imply the identity of concepts, and the identity of concepts would in turn imply the identity of thoughts, and thus the violation of the cognitive constraint that a rational subject cannot simultaneously adopt contradictory attitudes (acceptance and rejection) towards the same thought.
According to Frege, concepts are not individualized by reference alone, but by reference plus something else, which Frege calls the mode of presentation. What exactly is this? In all Fregean case examples, the subject has two distinct mental files referring to the same entity (without realizing that it is the same entity). This suggests that the something extra, playing the role of mode of presentation, is the mental file: if you change the mental file, you change the concept, even if the reference is the same.
But there's an ambiguity in this notion of mental file. In the previous lecture, I suggested distinguishing between two things: the file as such - which can be called the vehicle - and the concept, which is the content of the file. This distinction reveals the ambiguity I'm talking about: by mental file, we can understand either the file as such, independently of the content it conveys ("thin" file), or the file provided with a certain content (i.e. the vehicle + content set, which I call the "thick" file). Once this distinction has been made, we can show that the thick mental file, not the thin mental file, plays the role of presentation mode. Is this conclusion compatible with the idea that the content of a concept (the conception) is not constitutive of it and does not serve to individualize it? Yes, provided we distinguish between the concept (identified with the thin mental file) and the mode of presentation (identified with the thick mental file and integrating the design). The mode of presentation, in this perspective, is a phase, or temporal slice, of the concept, a phase characterized by, among other things, the conception conveyed by the concept at the moment in question.
