Moral judgements have to be universalizable. There are many problems with this thesis (U). The problems to be dealt with here, are: (i) What is the connection between U and justifiablility? (ii) Is U a logical thesis? (iii) Is U analytically true? (iv) Is U adaquate? (v) Is utilitarianism a logical consequence of U?

According to some critics Carnap's philosophy is "reflectioness", i.e. without epistemic content. In contrast to this assertion this essay will show that in the writings of Carnap's semantical period, especially in "Empiricism, Semantics, and Ontology", the fundamentals of an epistemology are developed. It may be called linguistic internalism. The exposition of frameworks are interpreted as an epistemological foundation of semantics. Several problems within this project are discussed, e.g. the determination of domains of frameworks, ontological existence sentences, the relation between theories and frameworks and limits of rationality.

There is a plurality of good reasons for action. An adequate theory of practical rationality has to be compatible with it even if it requires certain modifications of our everyday practices of reasoning. Usual theories of practical rationality do not pass this test. It is envisaged how to revise adequately our understanding of practical rationality.

This article argues for the thesis that there is only one basic form of rationality, which is applied in different areas. First of all, there is one meaning of the term "rational" which applies to all situations in which the term is used: "justified." If "rational" means simply "justified", then rationality can be broken down into as many types as there are kinds of justification. Two distinctions between kinds of justification seem particularly plausible: 1. relative vs. absolute justifications and 2. theoretical justifications of opinions vs. practical justifications of actions. Taken together, these two distinctions yield a division into four types of rationality. I maintain, however, that these two distinctions collapse upon more careful examination. In this article I will simply assume that no form of ultimate justification is convincing; thus, the first distinction does not apply. Against the second distinction I try to argue in this paper that theoretical rationality represents a form of practical rationality. The idea of an optimal choice of aims, actions, and opinions, which nonetheless differs from the orthodox model of practical rationality, thus proves to be the comprehensive central ingredient of the concept of rationality.

Some principles of logic-oriented theories of argumentation are discussed. A sharp distinction is drawn between arguments in formal contexts and arguments in non formal contexts. It is argued, that the analysis of colloquial arguments cannot be based on the logic-oriented theories of argumentation. The outline of a more realistic theory of argumentation is given, by using defeasable inferences as a starting point. The model is applied to some everyday arguments.

J. St. Mill's System of Logic (1843) is reexamined from the perspective of present-day analytical philosophy of the social sciences. His naturalistic epistemology, "state", "general/universal laws", "social statics/dynamics" are discussed, as well as his four methods. His nomological-behavioral position is analysed, along with his theoretical approach.