In the first part of this paper, the author analyzes several unacceptable views of properties of physical objects and justifies the familiar explication, according to which properties of physical objects are certain functions defined on the set of all couples w,t, where w is a possible world and t is a moment of time . On the background of the indicated understanding of properties, the author demonstrates that there exist empirical essential properties. An empirical property is understood as a property, (...) the extension of which cannot be identified without applying experience. He distinguishes two kinds of essential properties: purely essential and partially essential. A purely essential property has the same extension at every world-time couple. The extension of a partially essential properties changes in the logical space, but there exists a non-empty set of objects which is a subset of their extension at every world-time couple. Every partially essential property is empirical. The author pays special attention to the essential properties expressible by means of expressions of the form ∨ Q) where P, Q are non-essential empirical properties that are allied through some objects X1, ..., Xn - i.e., the property ∨ Q) belongs to the objects X1, ..., Xn at every world-time couple. In the last part of the paper, the author demonstrates that every empirical property of the type where ”<” denotes the relation of being a part of, and ”I” stands for any physical object, is purely essential. The assumption that the extensions of these properties are changeable, entails unacceptable consequences. (shrink)

The aim of the paper is to analyse and explicate the meanings the word „identification“ has in common language, philosophy of language and in P. Tichý’s theory of constructions. The author distinguishes acts of identification performed by a man from identification carried out by some expressions. He tries to argue that in case of expressions identifying is the same as referring and in case of Tichý’s constructions identifying means constructing.

Speaker’s reference is an intentional act directed, via an expression, at an object – an intentional object. The author of the paper tries to find an answer to the following question: What does a speaker refer to when he does not know what a description or a proper name used refers to? He argues that, if the speaker uses such a description, his reference is not directed at the referent of the description but at its meaning. If the speaker uses (...) a proper name whose meaning is not known to him, he can refer neither to the referent nor to the meaning of that name. (shrink)

The author of the article seeks to find an answer to the question whether it is possible to determine a priori the truth value of the statement „M = N“ where „M“ and „N“ are proper names of the same particular. He analyses the argumentation of the conception defending the positive answer to the question and tries to present arguments in favour of the opposite view. Let us suppose that the individual I is named by „M“ at time t1 and (...) by „N“ at time t2. If the individual changes considerably during the interval or presents us from quite different sides at t1 and t2, respectively , we will be unable to find out a priori, without certain empirical knowledge, whether M = N, although there were any doubts about the identity of the baptized individual neither at t1 nor at t2. (shrink)