  Reism had to meet several serious problems. It was very soon observed that (R2), one of the most important theses of reism, contained apparent names ‘state of affairs’, ‘relation’ and ‘property’. Hence, it should be disqualified as meaningless by reistic standards. In order to cope with this objection, Kotarbiński sharply distinguished semantic reism and ontological reism. He gradually ascribed a greater importance to semantic issues. For example, he was inclined to consider (R2) as a statement about the reistic language, that is, providing the condition for which names are admissible in our language. Another difficult problem came from various special fields and concerned the reistic interpretation of mathematics, logic, semantics, psychology sociology and the humanities. How should a reistic interpretation of set theory be presented? Is the concept of meaning explainable reistically? How should psyche, social rules or pieces of art be understood in the reistic frameworks? Kotarbiński hoped that mereology would provide a reistic alternative of set theory. He also offered a partial solution to other difficulties, but he finally recognized that the successes of reism were very partial. At the last stage, Kotarbiński considered reism rather as a program than as a theory of the world and language.  However, he always stressed that every form of progress in reism, even regional or local, is a cognitive success, because it introduces a language which is free of the dangers that result from using abstract words. In spite of these difficulties, reism attracted many philosophers, mainly in Poland.  Perhaps Tarski is the most notable example. He expressed sympathy for reism and even translated one of Kotarbiński’s papers into English, but he used Platonistic methods in his works on the foundations of mathematics.