It is at most only a small exaggeration to say that in analytic philosophy in America since the 1930's, outside of ethics, the topic of modality has received the most attention. In part, this is because so many of the central concepts of philosophy seem to lend themselves to a modal analysis; the concept of free-will, the concept of causation, and the concept of a disposition are but a few obvious examples, the concept of linguistic meaning may be another. That the central normative concepts of ethics and epistemology are themselves expressed by modal auxiliaries in natural language only serves to emphasize the centrality of the topic of modality to all branches of philosophical inquiry. But of course the metaphysical concepts of necessity and possibility are themselves philosophical both in character and tradition. The reemergence of these concepts as legitimate objects of study is one of the resounding success stories in the history of philosophy. The purpose of this seminar is to tell the story of their Twentieth Century rehabilitation.

Specifically, there are two tasks I want to accomplish this semester. The first is to provide an overview of the history of the discussion of modality in Twentieth Century philosophy. The second is to provide students with a background in the technical tools and philosophical issues grasp of which is presupposed in contemporary discussions of modality in philosophical logic, philosophy of language, and metaphysics. We will therefore not be breaking new ground in this seminar, and anyone caught doing so will be summarily expelled.

Our central purpose at the beginning of the seminar is to get a sense of why those in this early period turned to modal notions. After an introduction to propositional modal logic and tense logic, we will briefly discuss C.I. Lewis's systems for strict implication. We will then read the first chapter of Carnap's Meaning and Necessity. This will not only provide us with a glimpse at one possible semantics for quantified modal logic (the so-called "conceptual interpretation"), but it will also show how Carnap wanted to use modal notions in an analysis of meaning. The next phase of the course involves grappling with Quine's objections to the development of a semantics for quantified modal logic. In this section, we will read (a lot of) Quine, Carnap, Barcan-Marcus, Smullyan, and Follesdal. We will then turn to a close reading of Kaplan's intricate response to Quine, in "Opacity". We culminate this part of the course with a discussion of Kripke's classic "Semantical Considerations on Modal Logic" and then with a discussion of counterpart theory and the problem of transworld identification.

This background will prepare us for an informed reading of Kripke's Naming and Necessity. Given our interests, we will not focus on the philosophy of language and philosophy of mind aspects of the book. As we will have seen from some of the responses to Quine's objections to quantified modal logic, the use of quantified modal logic, on its objectual interpretation, does not bring with it serious essentialist commitments. However, Kripke does seem to draw out essentialist commitments from modal semantics. By this stage in the seminar, we should suspect that Kripke must be drawing on premises outside the modal semantics in reaching his controversial metaphysical conclusions about essences. We will focus on this aspect of Kripke's book in the seminar discussions, using Nathan Salmon's helpful discussions of controversial essentialist arguments in his book Reference and Essence.

After the discussion of Kripke, we will turn to a close reading of Allan Gibbard's paper "Contingent Identity", a sort of metaphysical version of the conceptual interpretation of quantified modal logic. We will conclude the course with some papers by Kit Fine on quantified modal logic and the representation of essentialist statements.

Schedule

Week 1: Introduction to modal propositional logic and quantificational tense logic, Lewis on strict implication.

Reading: pp. 1-18 of Graeme Forbes, The Metaphysics of Modality
Selections from Lewis and Langford, Symbolic Logic

Week 2: Introduction continued. Begin discussion of Chapter 1 of Carnap, Meaning and Necessity.

Chapter 1 of Rudolf Carnap, Meaning and Necessity.
Alonzo Church, "On Carnap's Analysis of Statements of Assertion and Belief"

Week 3. Quine's Objections to quantified modal logic.

W.V. Quine, "Notes on Existence and Necessity" (1943)
Quine, "The Problem of Interpreting Modal Logic" (1947)
Quine, "Three Grades of Modal Involvement" (1953)
Quine, "Reference and Modality" (1961)

Recommended: "A Functional Calculus of First Order Based On Strict Implication" (1946), Ruth Barcan. This is a technical paper, and it's not worth going through in detail unless you feel compelled.

Week 4. Early Responses to Quine's objections

Arthur Smullyan, "Modality and Description" (1948)
Ruth Barcan, "Modalities and Intensional Languages" (1961).
Dagfinn Follesdal, "Quantification into Causal Contexts" (1965)

Recommended: Barcan's "The Identity of Individuals in a Strict Functional Calculus of Second Order" (1947). We will be referring to various parts of this in our discussion of "Modalities and Intensional Languages."  It is useful to try to figure out how she derives the necessity of identity -- the claim that "material" identity and "strict" identity coincide.

Week 5. Contemporary Responses to Quine's objections

David Kaplan, "Opacity" (1986)

Recommended: Terence Parsons, "Essentialism and Quantified Modal Logic" (1969), Kit Fine, "The Problem of De Re Modality" (1989).

Week 6. Kripke on Quantified Modal Logic.

Saul Kripke, "Semantical Considerations on Modal Logic" (1963)

Week 7. Counterpart Theory

David Lewis, "Counterpart Theory and Quantified Modal Logic"
David Kaplan, "Transworld Heir Lines"
Allen Hazen, "Counterpart-theoretic Semantics for Modal Logic"

Week 8. Counterpart Theory (continued)

Graeme Hunter and William Seager, "The Discreet Charm of Counterpart Theory"
Graeme Forbes, "Canonical Counterpart Theory"
Graeme Forbes, "Free and Classical Counterparts"
Murali Ramachandran, "Contingent Identity in Counterpart Theory"
Graeme Forbes, "Counterparts, Logic, and Metaphysics: A Reply to Ramachandran"
Murali Ramachandran, "Unsuccessful Revisions to CCT"

Week 9. Naming and Necessity

Saul Kripke, Naming and Necessity

Week 10. Kripke, continued

Hilary Putnam, "Meaning and Reference"
Selections from Nathan Salmon, Reference and Essence.

Week 11. Contingent Identity

Allan Gibbard, "Contingent Identity"

Weeks 12-14: Fine on essentialism, to be planned in detail later.