Although the connections between Frege’s and Russell’s investigations are commonly known, there are some topics in their letters which do not seem to have been analysed until now: 1. Paradoxes formulated by Russell on the basis of Frege’s rules: a) „»ξ can never take the place of a proper name« is a false proposition when ξ is a proposition”; b) “A function never takes the place of a subject”. A solution of this problem was based on the reference/sense theory and (...) on the distinction between the first- and second-level names. 2. The inconsistency in Frege’s system may be avoided by the introduction of: a) a new kind of objects called quasi-objects ; b) logical types ; c) mathematics without classes ; d) some restrictions on the domain of function. 3. Since the inconsistency is connected with a class, what is class? In one of the letters, Frege compared a class to a chair composed of atoms. This approach seems to be similar to the collective understanding of a set. 4. Russell doubted that the difference between sense and reference of expressions was essential. Hence, Frege found some additional reasons to distinguish between them: semiotic, epistemological, from identity, and from mathematical practice. This discussion can be seen as a next step in developing the theory of descriptions by Bertrand Russell. (shrink)

It is widely known that Kasimir Twardowski was a student of Franz Brentano. In view of the fact that Brentano generally had great impact through his lectures, especially during his Vienna period (1874-1895), and consequently became one of the towering figures of Austrian philosophy, it is a matter of no small interest to determine how he influenced Twardowski. I’ll first consider presentations as they are described in Brentano’s psychology and then proceed to discuss Brentano’s account of the latter in his (...) logic. (shrink)