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.

Since the end of the 18th century philosophy has been going through an identity crisis which threatens its very existence. This crisis is due to the emancipation of the empirical sciences in the course of which philosophy has lost nearly all its traditional objects. We fi rst examine four traditional ways to overcome this crisis: philosophy as the all embracing universal science, philosophy as a priori knowledge, philosophy as common sense, philosophy as small talk. We show that these conceptions have grave shortcomings and therefore are not convincing. Instead we propose the following conception of philosophy: philosophy has to put and to answer radical questions, questions that spring from the conditions of human existence itself. We fi nally justify this conception by a refl ection on the history of philosophy and an analysis of the deep motivation of its founder, Socrates. This leads us to the insight that to engage in moral philosophy is itself a moral duty.

Es gibt zwei Versionen von Naturalismus in der Ethik: Der erste (Praktischer Naturalismus I) behauptet, daß jeder praktische Satz (der eine Norm oder ein Werturteil ausdrückt) äquivalent zu einem deskriptiven Satz ist. Der zweite (Praktischer Naturalismus II) sagt, daß die Gültigkeit von praktischen Sätzen ausschließlich von kontingenten empirischen Tatsachen abhängt. Um scharf zwischen diesen beiden Versionen zu unterscheiden, wird der Begriff der praktischen Gültigkeit eingeführt und in einer Form definiert, die sich radikal von Tarskis Konvention T unterscheidet. Die erste Version des Naturalismus wird generell als durch die Argumente von Moore und Hare widerlegt angesehen. Die zweite Spielart wurde bislang nicht widerlegt. Es wird versucht zu zeigen, daß der Praktische Naturalismus II, wenn er als radikaler Naturalismus formuliert wird, einen circulus vitiosus oder infiniten Regreß impliziert. Der einzige Weg, dies zu verhindern ist, zumindest ein praktisches Prinzip zuzulassen, dessen GüUigkeit nicht von kontingenten Tatsachen abhängt. Auf diese Weise hängt der Naturalismus in der Ethik von wenigstens einem transzendenten Prinzip ab.

Since more than 50 years Kant scholars debate the question whether the Law of Right as introduced in the Metaphysics of Morals by Kant can be justified by the Categorical Imperative. On the one hand we have those who think that Kant's theory of right depends from the Categorical Imperative, on the other hand we find a growing group of scholars who deny this. However, the debate has been flawed by confusion and misunderstanding of the crucial terms and principles. Therefore, my first task will be to clarify these terms and principles by introducing distinctions that have been neglected too often. After this I try to show a) that the Law of Right can in fact be justified by using the testing method the Categorical Imperative prescribes and b) that there is no other way to justify it. Doing this I criticize in detail the new arguments adherents of the independence thesis have recently put forward.