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 (t1, t2) or presents us from quite different sides at t1 and t2, respectively (e.g., as a mountain seen from different sides at the respective time moments), 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.