Ettore Casari

A starting point of Bolzano’s logical reflection was the conviction that among truths there is a connection, according to which some truths are grounds of others, and these in turn are consequences of the former, and that such a connection is objective, i.e. subsisting independently of every cognitive activity of the subject. In the attempt to account for the distinction between subjective and objective levels of knowledge, Bolzano gradually gained the conviction that the reference of the subject to the object is mediated by a realm of entities without existence that, recalling the Stoic lectà, are here called ‘lectological’. Moreover, of the two main ways through which that reference takes place—psychic activity and linguistic activity—Bolzano favoured the first and traced back to it the problems of the second; i.e. he considered those intermediate entities first as possible content of psychic phenomena and only subordinately, on the basis of a complex theory of signs, as meanings of linguistic phenomena. This book follows this schema and treats, in great detail, first, lectological entities (ideas and propositions in themselves), second, cognitive psychic phenomena (subjective ideas and judgements), and, finally, linguistic phenomena. Moreover, it tries to bring to light the extraordinary systematic character of Bolzano’s logical thought and it does this showing that the main logical ideas developed principally in the first three parts of the Theory of Science, published in 1837, can be effortlessly formally presented within the well-known Hilbertian epsilon-calculus.

Ristampa dell'omonimo Cap. 3 del Vol. III, Le discipline filosofiche, de La Filosofia, diretta da Paolo Rossi, UTET, Torino 1995, pp. 187-322; nuova ristampa in N. Abbagnano, G. Fornero, P. Rossi, Filosofia. Storie, Parole, Temi, Vol. 19, Corriere della sera, 2019, pp. 177-312.

The paper focuses on the historical background and the philosophical merits of the trend in logic, which, beginning in the seventies, has given new life to Meinong’s attempt to solve, by means of a theory encompassing both existing and non-existing objects, the problem raised by Brentano’s claim that psychic phenomena are always directed towards an object. Meinong’s approach had been eradicated from the philosophical debate by Russell: not so much by his direct objections to the theory, but rather by his shifting the question from the ontological to the linguistic level (from the things which do not exist to the terms which do not denote). The revival of Meinong’s point of view has developed along two directions, corresponding to quite different ideas suggested by Mally in order to face Russell’s objections. The first approach – especially supported by Terence Parsons – distinguishes two kinds of properties: the so called «nuclear» properties, which somehow directly characterize the object (e.g. being red, being a man, being a book) and, on the other side, the «extranuclear» properties, which are external to the nature of the objects (e.g. being existent, being possible, being thought by someone). The second approach – most thoroughly developed by Edward Zalta – distinguishes two types of «copula», i.e. two types of relations between an object and a property: the enjoying of a property by an object and, on the other side, the entering of a property into the «definition» of an object.