Gerhard Seel

In his precritical period Kant developed a demonstration of the existence of God that he believed to be the only possible one. Whether this argument is valid is a much-disputed question. To give an answer to this question I will reconstruct Kant’s argument with the means of modern logic and semantics and show which are—in my view—it’s weak points. To achieve this, I will use a combination of the formalism of predicate-, propositional and modal logic without, thought, introducing such a combined logic.

As an introduction to the plenary session “Metaphysics and Aesthetics” in my article I try to describe the state of philosophy of art today and give an outlook to its future development. In the last century analytical philosophy of art has been occupied with the following four questions: What is the essence of art? What is the ontological status of works of art? What are aesthetic qualities and how do we come to know them? Have aesthetic value judgments objective validity? In the first step I explain why analytical philosophy of art failed to answer these questions and what this failure has to do with the end of art. In the second step I attempt to give a definition of art myself which allows to show that this failure and the end of art were inevitable. Finally I try—as a consequence—to define the general features of the art of the future.

Kant distinguishes two kinds of knowledge of one-self: empirical self-knowledge due to inner sense and a priori self-knowledge achieved by transcendental apperception. This conception encounters a host of problems. I try to solve these problems from the perspective of today’s phenomenology and analytical philosophy. I first introduce a new conception of inner sense and time-consciousness and argue that empirical self-knowledge must be based on the category of person, a category Kant did not list in his table of categories. I explain how the schematism of this category works. Then I introduce the a priori notion of the subject which corresponds to Kant’s ‘I think’. However, unlike Kant I hold that the notion of the subject is the notion of a being which has certain a priori capacities. Kant did not see that the term ‘I’ must be conceived of as an indexical. I argue that this indexical refers to both, the subject who does the thinking and the person who is thought. On this basis I give an answer to the question how genuine de-se knowledge is possible. I further defend—against Wittgenstein and others—the use of a private thought language. Finally, I show that what I have developed is—notwithstanding the refutation of important elements of Kant’s theory—still essentially a Kantian approach.

Following Richard M. Hare1 I think that we use practical sentences as decision criteria. We understand their meaning if we know what decision to take according to them. But it is not clear, how exactly decision criteria are related to decisions and how they function as criteria. To fully understand this role, we need a formal semantics of practical sentences. For this I have to introduce a formal language and give an interpretation of it. This language has to be constructed in such a way that a translation into ordinary language is always possible in principle. Thus, we make sure that our semantics and logic will have an impact on the solution of concrete practical problems. According to this program I will first introduce the formal language ‘LP1’. To give an interpretation of it I will then clarify what a decision is and show how practical sentences function as decision criteria. On this basis I give an interpretation of the primitive two-place operator ‘PT p,q’ and the one-place operator ‘VTp’. I further argue that we make meta-decisions concerning the application of first-order decision-criteria. This allows me to introduce a new concept of practical validity, which differs radically from the concept of truth. Using this concept, I then give an interpretation of the deontic operators ‘OTp’, ‘FTp’, ‘ATp’ and ‘ITp’. The concept of practical validity makes it also possible to introduce practical logical connectors and mixed logical connectors on the basis of practical or mixed value tables. These connectors are used – among others – in bridge-principles, which play an important role in ethical and juridical theories. Finally, I shortly explain the semantics of the main kinds of practical sentences, i.e. value judgments, imperatives, norms and intentions, and I argue that we need a deontic logic in order to use practical sentences in a correct way.