Intensionalismi

Intensionalismi is a philosophical concept that deals with the meaning of terms and propositions, particularly in relation to their logical properties and how they are understood. It is often contrasted with extensionalism, which focuses on the set of things that a term or proposition refers to. Intensionalists argue that the meaning of a term or proposition is not solely determined by what it refers to, but also by the way in which it refers to it, or by the concept or idea it expresses.

In logic and philosophy of language, intension refers to the set of properties that define a concept or term. For example, the intension of the term "bachelor" might be "an unmarried man." An extension, on the other hand, would be the set of all bachelors. Intensionalism suggests that understanding "bachelor" involves grasping the concept of being an unmarried man, not just knowing who all the bachelors are. This is particularly important when dealing with modal contexts (like necessity and possibility) or opaque contexts (like belief and knowledge), where substituting co-referential terms can change the truth value of a statement.

For instance, the statement "The morning star is Venus" is true, and "The evening star is Venus" is also true. Under an extensionalist view, since "the morning star" and "the evening star" both refer to Venus, they should be interchangeable in all contexts without changing truth values. However, the statement "It is necessary that the morning star is Venus" is true, while "It is necessary that the evening star is Venus" is also true. But if we consider "The President believes the morning star is Venus" and "The President believes the evening star is Venus," it's possible for one to be true and the other false, demonstrating a difference in meaning beyond mere reference. Intensionalism seeks to account for these nuances by considering the conceptual content.