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Works available only in Polish are not enclosed


A complete bibliography up to 1997 (with the works published in Polish and not translated in other languages) can be found in: Kazimierz Twardowski, On Actions, Products and Other Topics in Philosophy, Amsterdam: Rodopi, 1999, pp. 287-297.

  1. Twardowski, Kazimierz. 1891. Idee und Perzeption. Eine erkenntnis-theoretische Untersuchung aus Descartes. Wien: Konegan.

  2. ———. 1894. Zur Lehre vom Inhalt und Gegenstand der Vorstellungen. Eine Psychologische Untersuchung. Wien: Hölder.

    Nachdruck: München: Philosophia Verlag 1982 mit Einleitung von Rudolf Haller.

  3. ———. 1902. "Über sogennante relative Wahrheiten." Archiv für Systematische Philosophie no. 8:415-447.

    Translation by M. Wartenberg of a an essay published in Polish (1900).

    Reprinted in D. Pearce, Jan Wolenski (eds.), Logische Rationalismus. Philosophische Schriften der Lemberg-Warschauer Schule, Frankfurt am Main: Athenäum, 1989, pp. 38-58.

  4. ———. 1902. "Über begriffliche Vorstellungen." Verlag der Philosophischen Gesellschaft in Wien.

    Conference held 18th November 1902 (28 pages).

  5. ———. 1911. "Seches Vorlesungen über die mittelaterliche Philosophie." Die Philosophie der Gegenwart no. 3:58-59.

    German summary of a book in Polish.

  6. ———. 1911. "Über die Methode der Psychologie. ein Beitrag zur vergleichenden Methodologie der Wissenschaften." Die Philosophie der Gegenwart no. 3:272.

    German summary of an articole published in Polish in 1910.

  7. ———. 1911. "Über Funktionen und Gebilde. Einige Bemerkungen zum Grenzgebiet der Psychologie, Grammatic, und Logik." Die Philosophie der Gegenwart no. 3:214.

    German summary of an essay published in Polish in 1912.

  8. ———. 1991. "Selbstdarstellung (1926)." Grazer Philosophische Studien no. 39:1-24.

    Edited by Jan Wolenski and Th. Binder.

    English translation as Self-Portrait in: On actions, Products and Others Topics in Philosophy.

  9. ———. 1996. "Funktionen ung Gebilde." Conceptus no. 29:157-186.

    Original Polish edition 1912.

    English translation in On Actions, Products and Others Topics in Philosophy.

  10. ———. 2016. Logik: Wiener Logikkolleg 1894/95. Berlin: Walter de Gruyter.

    Herausgegeben von Arianna Betti und Venanzio Raspa.


  1. Brandl, Johannes, and Wolesnki, Jan, eds. 1999. Kazimierz Twardowski on Actions, Products and Other Topics in Philosophy. Amsterdam: Rodopi.

    Translated and annotated by Arthur Szylewicz.

    Contents: Introduction 7; Translator's note 15; Self-portrait (1926/91) 17; Biographical notes 33;

    I. On mind, psychology and language.

    Psychology vs. physiology and philosophy (1897) 41; On the classification of mental phenomena (1898) 65; The essence of concepts (1903/24) 73; On idio- and allogenetic theories of judgment (1907) 99; Actions and products (1912) 103; The Humanities and psychology (1912/76) 133; On the logic of adjectives (1923/27) 141;

    II. On truth and knowledge.

    On so-called relative truths (1900) 147; A priori, or rational (deductive) sciences and a posteriori, or empirical (inductive) sciences (1923) 171; Theory of knowledge. A lecture course (1925/75) 181;

    III. On philosophy.

    Franz Brentano and the history of philosophy (1895) 243; The historical conception of philosophy (1912) 255; On clear and unclear philosophical style (1920) 257; Symbolomania and pragmatophobia (1921) 261;

    Address at the 25th anniversary session of the Polish Philosophical Society (1929/31) 271; On the dignity of the University (1933) 277;

    Bibliography 287-297.

  2. Brożek, Anna, and Jadacki, Jacek, eds. 2014. On Prejudices, Judgments and Other Topics in Philosophy. Amsterdam: Rodopi.

  3. Twardowski, Kazimierz. 1977. On the Content and Object of Presentations. A Psychological Investigation. The Hague: Martinus Nijhoff.

    Translation and introduction by Reinhardt Grossmann of Zur Lehre vom Inhalt und Gegenstand der Vorstellungen.

  4. ———. 1979. "Actions and Products. Comments on the Border Area of Psychology, Grammar and Logic." In Semiotics in Poland 1894-1969, edited by Pelc, Jerzy, 13-27. Dordrecht: Reidel.

    Abridged translation by O. Wojtasiewicz of a Polish text of 1912.

    New complete translation in On actions, Products and Others Topics in Philosophy.

  5. ———. 1979. "On Clear and Obscure Styles of Philosophical Writings." In Semiotics in Poland 1894-1969, edited by Pelc, Jerzy, 1-2. Dordrecht: Reidel.

    Abridged translation by O. Wojtasiewicz of a Polish text of 1920.

    New complete translation in On actions, Products and Others Topics in Philosophy.

  6. ———. 1979. "Symbolomania and Pragmatophobia." In Semiotics in Poland 1894-1969, edited by Pelc, Jerzy, 3-6. Dordrecht: Reidel.

    Abridged translation by O. Wojtasiewicz of a Polish text of 1921.

    New complete translation in On actions, Products and Others Topics in Philosophy.

  7. ———. 1979. "Issues in the Logic of Adjectives." In Semiotics in Poland 1894-1969, edited by Pelc, Jerzy, 28-30. Dordrecht: Reidel.

    Abridged translation by O. Wojtasiewicz of a Polish text of 1927.

    New complete translation in On actions, Products and Others Topics in Philosophy.

  8. ———. 1995. "Imageries." Axiomathes no. 1:79-104.

    Original Polish edition 1898.

  9. ———. 1995. "Remarks on the Classification of Views on the Relation between the Soul and the Body." Axiomathes no. 6:25-29.

    Original Polish edition 1909.

  10. ———. 1997. "The Majesty of the University." In The Idea of the University, edited by Brzezinski, Jerzy and Nowak, Leszek, 9-17. Amsterdam: Rodopi.

  11. ———. 2015. "Contemporary Philosophy on Immortality of the Soul." Studia Neoaristotelica no. 12:72-83.

    Translation of an essay published in Polish in 1895.

  12. ———. 2015. "The Metaphysics of the Soul." Studia Neoaristotelica no. 12:84-98.

    Translation of an essay published in Polish in 1895.


  1. ———. 2007. "Fonctions et formations." In A l'école de Brentano. De Würzbourg à Vienne, edited by Fisette, Daniel and Fréchette, Guillaume, 343-385. Paris: Vrin.

  2. Twardowski, Kazimierz, and Husserl, Edmund. 1993. Sur les objets intentionnels (1893-1901). Paris: Vrin.

    French translation of Zur Lehre vom Inhalt und Gegenstand der Vorstellungen and other texts by Edmund Husserl.

    K. Twardowski: Sur la théore du contenu et de l'objet des représentations

    E. Husserl: Intuition et re-présentation, Intuition et remplissement, Objets intentionnels et divers extes annexes

    Présentation, traduction, notes, remarques et index pat Jacques English.

    "Avertissement. Le présent ouvrage est la traduction, d'une part, de l'ouvrage de Kasimir Twardowski, Zur Lehre vom Inhalt und Gegenstand der Vorstellungen et, d'autre part, de toute une série de textes d'Edmund Husserl, s'échelonnant de 1893 à 1901, qui se rattachent, de près ou de loin, à la question des objets intentionnels, telle que l'avait posée Twardowski, et qui ont tous été publiés (sauf un) par Bernhard Rang en 1979 chez Martinus Nijhoff dans le Tome XXII des Husserliana, Aufsätze und Rezensionen (1890-1910)."


  1. Twardowski, Kazimierz. 1988. Contenuto ed oggetto. Torino: Bollati Boringhieri.

    Italian translation by Stefano Besoli of: Idee und Perzeption. Eine erkenntnis-theoretische Untersuchung aus Descartes (pp. 25-53) and Zur Lehre vom Inhalt und Gegenstand der Vorstellungen (pp. 57-169).

    With an introduction by Stefano Besoli: La rappresentazione e il suo oggetto: dalla psicologia descrittiva alla metafisica, pp. 7-21.

  2. ———. 1991. "Sulle cosiddette verità relative." Discipline Filosofiche no. 2:1-31.

    Original Polish edition 1900.

    English translation in On actions, Products and Others Topics in Philosophy.

  3. ———. 1998. "Funzioni e prodotti." Axiomathes no. 3:325-359.


  1. Albertazzi, Liliana. 1993. "Brentano, Twardowski and Polish Scientific Philosophy." In Polish Scientific Philosophy: the Lvov-Warsaw School, edited by Coniglione, Francesco, Poli, Roberto and Wolenski, Jan, 11-40. Amsterdam: Rodopi.

  2. Betti, Arianna. 2006. "Sempiternal Truth. The Bolzano-Twardowski-Leśniewski Axis." In The Lvov-Warsaw School. The New Generation, edited by Jadacki, Jacek Jusliuz and Pasniczek, Jacek, 371-399. Amsterdam: Rodopi.

  3. ———. 2006. "The Strange Case of Savonarola and the Painted Fish. On the Bolzanization of Polish Thought." In Actions, Products, and Things. Brentano and Polish Philosophy, edited by Chrudzimski, Arkadiusz, 55-81. Frankfurt: Ontos Verlag.

    "I have previously discussed in several papers specific Bolzanian elements present in the Polish tradition. This paper will not, for the most part, add anything in particular to that. The new - and rather blunt hypothesis to be put forward here is that, despite appearances, Twardowski also contributed de facto to slowing down the reception of Bolzano's most modem logical discoveries. For in Poland Bolzano was to remain one logician among many for rather long. It was chiefly thanks to two factors that Bolzano's star could, slowly, begin to rise in Poland, or, at least, that the fundamental achievements of his logic could be known. One factor is antipsychologistic (more precisely Platonistic) influence coming from Husserl and from Twardowski's student Łukasiewicz. The other factor is the change in the conception of logic which took Polish logic from, say, Sigwart, to Tarski through Leśniewski and Łukasiewicz," p. 55

  4. ———. 2013. "We Owe It to Sigwart! A New Look at the Content/object Distinction in Early Phenomenological Theories of Judgment from Brentano to Twardowski." In Judgement and Truth in Early Analytic Philosophy and Phenomenology, edited by Textor, Mark, 74-96. Basingstoke: Palgrave Macmillan.

  5. Betti, Arianna, and Schaar, Maria van der. 2004. "The Road from Vienna to Lvov: Twardowski's Theory of Judgement Between 1894 and 1897." Grazer Philosophische Studien no. 67:1-20.

    "In several manuscripts, written between 1894 and 1897, Twardowski developed a new theory of judgment with two types of judgment: existential and relational judgments. In Zur Lehre he tried to stay within a Brentanian framework, although he introduced the distinction between content and object in the theory of judgment. The introduction of this distinction forced Twardowski to revise further Brentano's theory. His changes concerned judgments about relations and about nonpresent objects. The latter are considered special cases of relational judgments. The existential judgments are analyzed in a Brentanian way."

  6. Bobryk, Jerzy. 2009. "The Genesis and History of Twardowski's Theory of Actions and Products." In The Golden Age of Polish Philosophy. Kazimierz Twardowski's Philosophical Legacy, edited by Lapointe, Sandra, Wolenski, Jan, Marion, Mathieu and Miskiewicz, Wioletta, 33-42. New York: Springer.

  7. Brandl, Johannes. 1998. "Twardowski's Distinction between Actions and éroducts." In The Lvov-Warsaw School and Contemporary Philosophy, edited by Kijania-Placek, Katarzyna and Wolenski, Jan, 23-34. Dordrecht: Kluwer.

  8. Brożek, Anna. 2014. "The significance of Kazimierz Twardowski in philosophy and culture." PRO-FIL no. 15:32-46.

  9. Buczynska-Garewicz, Hanna. 1980. "Twardowski's Idea of Act and Meaning." Dialectic and Humanism no. 3:153-164.

  10. ———. 1985. "Twardowski's Concept of Sign and Meaning." In Semiotics 1984, edited by Deely, John, 557-565. Lanham: University Press of America.

  11. Cavallin, Jens. 1996. "The Metaphysics of the Analysis of Mind." Axiomathes no. 3:335-350.

  12. ———. 1997. Content and Object. Husserl, Twardowski and Psychologism. Dordrecht: Kluwer.

  13. ———. 2001. "Contents. Psycho-physical Products and Representations. Some notes on the Theories of Kazimierz Twardowski." In The Dawn of Cognitive Science. Early European Contributors, edited by Albertazzi, Liliana, 185-208. Dordrecht: Kluwer.

  14. Czarnecki, Tadeusz. 1998. "Inspirations and Controversies: from the Letters between K. Twardowski and A. Meinong." In The Lvov-Warsaw School and Contemporary Philosophy, edited by Kijania-Placek, Katarzyna and Wolenski, Jan, 35-42. Dordrecht: Kluwer.

  15. Czezowski, Tadeusz. 1948. "Kazimierz Twardowski as a Teacher." Studia Philosophica 1939-1946 no. 3:11-17.

  16. ———. 1960. "Tribute to Kazimierz Twardowski on the 10th Anniversary of His Death in 1938." Journal of Philosophy no. 57:209-215.

  17. Fréchette, Guillaume. 2012. "Twardowski on Signs and Products." Paradigmi no. 30:61-75.

  18. Hickerson, Ryan. 2005. "Getting the Quasi-Picture: Twardowskian Representationalism and Husserl's Argument Against It." Journal of the History of Philosophy no. 43:461-480.

  19. ———. 2007. The History of Intentionality. New York: Continuum.

    Contetns: Acknowledgements IX; Introduction 1; 1. What was Brentano's problem? Physical phenomena in Psychology from empirical standpoint 21; 2. Getting the quasi-picture: Twardowski's On the content and object of representations 45; 3. Not getting the quasi-picture: Husserl critique of Twardowski 57; 4. Phenomenology without phenomena: Husserl's break with Brentano 65; 5. Husserl's riddle and the 'real' content of consciousness: a Jamesian reading of Logical Investigations V 83; Conclusion 109; Appendix: The text and reception of the Logical Investigations 121; Notes 125; Bibliography 159; Index 169.

  20. Ingarden, Roman. 1948. "The Scientific Activity of Kazimierz Twardowski." Studia Philosophica 1939-1946 no. 3:17-30.

  21. Jacquette, Dale. 1987. "Twardowski on Content and Object." Conceptus.Zeitschrift für Philosophie no. 21:193-199.

    "Kasimir Twardowski's reduction of psychological experience to an act, Content, and Object had a decided impact on the development of modern phenomenology and the theory of objects of Alexius Meinong, Ernst Mally, And the Graz school of philosophical semantics and psychology.

    Twardowski offers four arguments to show that the content and object of a presentation can never be same. These conclusions are challenged by a formal diagonal counterexample in which it is possible for the content and object of a thought to be precisely identical.

    Twardowski's reduction and the act-Content-Object structure of psychological experience may nevertheless be upheld in somewhat different form not as an exclusive but as a nonexclusive kind of distinction."

  22. ———. 1990. "The Origins of Gegenstandstheorie. Immanent and Transcendent Intentional objects in Brentano, Twardowski and Meinong." Brentano Studien.Internationales Jahrbuch der Franz Brentano Forschung no. 3:177-202.

  23. ———. 2006. "Twardowski, Brentano's Dilemma, and the Content-Object Distinction." In Actions, Products, and Things. Brentano and Polish Philosophy, edited by Chrudzimski, Arkadiusz and Łukasiewicz, Dariusz, 9-34. Frankfurt: Ontos Verlag.

  24. Jadacki, Jacek Jusliuz. 1992. "The Metaphysical Basis of Kazimierz Twardowski's Descriptive Semiotics." In Theories of Objects: Meinong and Twardowski, edited by Pasniczek, Jacek, 57-74. Lublin: Wydawnictwo Uniwersytetu Marii Curie-Slodowskiej.

  25. ———. 1993. "Kazimierz Twardowski's Descriptive Semiotics." In Polish Scientific Philosophy: the Lvov-Warsaw School, edited by Coniglione, Francesco, Poli, Roberto and Wolenski, Jan, 191-206. Amsterdam: Rodopi.

    " Kazimierz Twardowski's contribution to semiotics has been fourfold: as a "critic" of others conceptions, a "constructor" of his own analyses, distinctions, and theses, a "precursor" of new ideas and methods, and an "inspirer" of posterior polemics (especially in Lvov-Warsaw School). The work bears the detail presentation of Twardowski's semiotic views, showing that his theory consists in the psycho-physical conception of signs, the functional conception of expression, the noematic conception of sense, and the discrepant conception of language. The reach bibliography contains the list of 21 Twardowski's works on semiotics, and of 43 works on his views."

  26. Jedynak, Anna. 2009. "French and Polish Conventionalism." In The Golden Age of Polish philosophy. Kazimierz Twardowski's Philosophical Legacy, edited by Lapointe, Sandra, Wolenski, Jan, Marion, Mathieu and Miskiewicz, Wioletta, 61-77. New York: Springer.

  27. Kleszcz, Ryszard 2016. "Kazimierz Twardowski on Metaphysics." In Tradition of the Lvov-Warsaw School. Ideas and Continuations, edited by Brożek, Anna, Chybińska, Alicja, Jadacki, Jacek and Wolenski, Jan, 135-152. Leiden: Brill.

  28. Kujundicz, Nebojsa. 2001. "On the Logic of Adjectives." Dialogue.Canadian Philosophical Review no. 40:803-809.

  29. Lapointe, Sandra, Wolenski, Jan, Marion, Mathieu, and Miskiewicz, Wioletta, eds. 2009. The Golden Age of Polish Philosophy. Kazimierz Twardowski's Philosophical Legacy. New York: Springer.

    Contents: Acknowledgments V-VI; Sandra Lapointe, Jan Wolenski: Introduction 1; Part I. Twardowski and Polish scientific philosophy. 1. Dariusz Łukasiewicz: Polish metaphysics and the Brentanian tradition 19; 2. Jerzy Bobryk: The genesis and history of Twardowski's theory of actions and products 33; Jan Wolenski: The rise and development of logical semantics in Poland 43; Anna Jedynak: French and Polish conventionalism 61; Part II. Philosophy of logic and mathematics. 5. Grzegorz Malinowski: A philosophy of many-valued logic. The third logical value and beyond 81; 6. Arianna Betti: Leśniewski's systems and the Aristotelian model of science 93; 7. Denis Miéville: Leśniewski, negation, and the art of logical subtlety 113; 8. Roman Murawski: Philosophy of mathematics in the Lvov-Warsaw School 121; 9. Paolo Mancosu: Tarski's engagement with philosophy 131; 10. Douglas Patterson: Tarski on definition, meaning and truth 155; Part III. Polish Philosophy of Mind. 11. Urszula M. Zeglen: A note on Henryk Mehlberg's contribution to the debate on the mind-body problem 173; 12. Wioletta Miskiewicz: Leopold Blaustein's analytical phenomenology 181; Part IV. Around Twardowski's School. 13. Katarzyna Kijania-Placek: Non-classical conceptions of truth in Polish philosophy at the beginning of the 20th century 191; 14. Bernard Linsky: Chwistek's theory of constructive types 203; 15. Claude Panaccio: Konstanty Michalski on late medieval nominalism 221; 16. Roger Pouivet: Jan Samalucha's analytical Thomism 235; Index 247-251.

  30. Łukasiewicz, Dariusz. 2009. "Polish Metaphysics and the Brentanian Tradition." In The Golden Age of Polish philosophy. Kazimierz Twardowski's Philosophical Legacy, edited by Lapointe, Sandra, Wolenski, Jan, Marion, Mathieu and Miskiewicz, Wioletta, 19-31. New York: Springer.

  31. Moltmann, Friederike. 2014. "Attitudinal Objects and the Distinction between Actions and Products." Canadian Journal of Philosophy no. 43:579-701.

  32. Pasniczek, Jacek, ed. 1992. Theories of Objects: Meinong and Twardowski. Lublin: Wydawnictwo Uniwersytetu Marii Curie-Slodowskiej.

    Contents: Jacek Pasniczek: Preface 7; Francesca Modenato: Alexius Meinong: the theory of relation as a theory of knowledge 9; Liliana Albertazzi: Is there a transcendental object? 26; Roberto Poli: Twardowski and Wolff 45; Jacek Juliusz Jadacki: The metaphysical basis of Kazimierz Twardowski's descriptive semiotics 57; Jan Wolenski: 'Being' as a syncategorematic word: a completion (?) of Twardowski's analysis of 'nothing' 75; Dale Jacquette: Meinongian models of scientific law 86; Jacek Pasniczek: The Meinongian logic vs. the Classical logic 105-112.

    This volume contains a selection of papers from the conference "The Theory of Objects in Central Europe. The Austrian-Polish Connection: Meinong and Twardowski" held in December 1989 in Kraków. It was supported and sponsored by the Jagiellonian University, Centro Studi per la Filosofia Mitteleuropea, The National Research Project "Sign-Language-Reality", and The Institute of Austrian Culture in Warsaw. The conference was organized by Prof. Jan Wolenski with dr. Georg Jankovic's generous assistance.

    Alexius Meinong and Kazimierz Twardowski studied philosophy at the University of Vienna at the end of XIX century. Both were under a great influence of Franz Brentano, who is considered the father of contemporary theory of intentionality. He viewed intentionality as the crucial feature of consciousness consisting in „directness to an object". Such conception should presuppose some general theory of objects of consciousness. Meinong and Twardowski adopted Brentano's idea of intentionality subsequently elaborating their own ontologies of objects. What is common in the views of the two philosophers, barring many differences, is that they assume an extensive sphere of non-existent objects that can be possibly objects of intentional acts.

    Nowadays there is a growing interest in theories of intentionality and intentional objects on the part of analytic philosophy as well as phenomenology. That is why there is also a renaissance of Meinong's and Twardowski's philosophical thought, although the former philosopher is much better known, more popular, and, what follows, more inspiring. The main purpose of the conference that took place in Kraków was to investigate, from various historical and theoretical perspectives, theories of objects created by the two of Brentano's followers. It is to be regretted that the present volume does not fill a serious gap in philosophical literature: no paper is devoted to direct comparison of Meinong and Twardowski. Nevertheless we hope that the papers collected in the volume may contribute to better understanding of the two philosophers and prepare the ground for such a comparative study.

    F. Modenato, in her essay, traces the development of Meinong's idea of relations while linking his views with the views of Hume and Locke. She is concentrating on epistemological relevance of the idea. Relations are treated by Meinong as some complexities and both relations and complexities are higher-order objects. Higher-order objects play the central role in Meinong's theory of knowledge and are of great importance to his ontology.

    L. Albertazzi points to some Kantian motives in Twardowski's ontology. The Polish philosopher distinguishes several categories of objects which, according to Albertazzi's interpretation, correspond closely to that distinguished by Kant. In particular, 'the object in general' may be taken as Kant's transcendental object, and 'the general object' as a universal presented individually in the subject of proposition.

    R. Poli argues in his paper that many elements of Wolff's ontology can be found in Twardowski's theory of objects. Both philosophers conceive objects as possible wholes. For Twardowski, being an object is ontologically prior to having existence and it is enough for being an object to be representable in an act of presentation.

    J.J. Jadacki presents a comprehensive survey of Twardowski's ontological (metaphysical) and epistemological views. On this basis he reconstructs the philosopher's descriptive semiotics focusing his attention on the theory of judgment.

    Additionally, Jadacki carries out a formal semantic analysis of Twardowski's semiotics.

    J. Wolenski considers the main traditional views of 'being' and wonders if 'being' could be situated somewhere in the formal hierarchy of concepts. He comes to the conclusion that "being" expresses no concept at all and, what follows, it has the syncategorematic character as Twardowski claimed. Wolenski proposes a completion of Twardowski's claim by appealing to modern logic and Leśniewski's ontology.

    D. Jacquette sketches informally the principles of Meinongian semantics and shows how the semantics can be applied in formalisation of scientific laws. By contrast to extensionalist models of scientific discourse which admit only existent objects, in Meinongian semantics the reference to ideal and non-existent objects is possible. Many problems of contemporary philosophy of science such as, for example, the justification of induction and confirmation can be uniformely treated and solved on the ground of Meinong's theory.

    J. Pasniczek proposes quite a simple logic which obeys the main theses of Meinong's theory of objects. This logic resembles closely the classical predicate logic with respect to syntax and semantics (it is basically extensional). Despite that resemblance, the proposed logic is associated with very rich ontology of objects including various kinds of non-existent objects.

    I am deeply indebted to Prof. Jan Wolenski for encouragement and assistance in editing this book." (Preface, pp. 7-8)

  33. Placek, Tomasz. 1996. "Thought as a Product of Thinking." Conceptus.Zeitschrift für Philosophie no. 24:191-203.

    "This paper advocates the view that thoughts which are qualitatively the same are also numerically identical. The point of departure is the puzzle: if thoughts are unchanging and eternal inhabitants of a "third realm", then it is mysterious how we grasp them, whereas, the assumption that they are outputs of some mental processes casts doubt on the possibility of communicating thoughts. To solve the puzzle Twardowski's teaching on actions and their products is applied and further elaborated."

  34. Poli, Roberto. 1992. "Twardowski and Wolff." In Theories of Objects: Meinong and Twardowski, edited by Pasniczek, Jacek, 45-56. Lublin: Wydawnictwo Uniwersytetu Marii Curie-Slodowskiej.

  35. ———. 1993. "Twardowski's Theory of Modification Against the Background of Traditional Logic." Axiomathes no. 4:41-57.

  36. ———. 1996. "Kazimierz Twardowski (1866–1938)." In The School of Franz Brentano, edited by Albertazzi, Liliana, Libardi, Massimo and Poli, Roberto, 207-231. Dordrecht: Reidel.

  37. Rojszczak, Artur. 1998. "Truth-bearers from Twardowski to Tarski." In The Lvov-Warsaw School and Contemporary Philosophy, edited by Kijania-Placek, Katarzyna and Wolenski, Jan, 73-84. Dordrecht: Kluwer.

  38. ———. 2005. From the Act of Judging to the Sentence. The Problem of Truth Bearers from Bolzano to Tarski. Dordrecht: Springer.

  39. Rollinger, Robin D. 1999. Husserl's Position in the School of Brentano. Dordrecht: Kluwer.

    See Chapter 5: Husserl and Twardowski, pp. 139-154.

  40. ———. 2009. "Brentano's Psychology and Logic and the Basis of Twardowski's Theory of Presentations." The Baltic International Yearbook of Cognition, Logic and Communication:1-23.

  41. Rosiak, Marek. 1998. "Twardowski and Husserl on Wholes and Parts." In The Lvov-Warsaw School and Contemporary Philosophy, edited by Kijania-Placek, Katarzyna and Wolenski, Jan, 85-100. Dordrecht: Kluwer.

  42. Schaar, Maria van der. 1996. "From Analytic Psychology to Analytic Philosophy; the Reception of Twardowski’s Ideas in Cambridge." Axiomathes no. 4:295-324.

  43. ———. 2006. "On the Ambiguities of the Term Judgement. An Evaluation of Twardowski's Distinction between Action and Product." In Actions, Products, and Things. Brentano and Polish Philosophy, edited by Chrudzimski, Arkadiusz and Łukasiewicz, Dariusz, 35-54. Frankfurt: Ontos Verlag.

  44. ———. 2015. Kazimierz Twardowski: A Grammar for Philosophy. Leiden: Brill.

  45. Schuhmann, Karl. 1993. "Husserl and Twardowski." In Polish Scientific Philosophy: the Lvov-Warsaw School, edited by Coniglione, Francesco, Poli, Roberto and Wolenski, Jan, 41-58. Amsterdam: Rodopi.

  46. Simons, Peter M. 2009. "Twardowski on Truth." The Baltic International Yearbook of Cognition, Logic and Communication no. 4:1-14.

  47. Simons, Peter M., and Wolenski, Jan. 1989. "De Veritate: Austro-Polish Contributions to the Theory of Truth from Brentano to Tarski." In The Vienna Circle and the Lvov-Warsaw School, edited by Szaniawski, Klemens, 391-442. Dordrecht: Kluwer.

  48. Skolimowski, Henryk. 1967. Polish Analytical Philosophy. A Survey and a Comparison with British Analytical Philosophy. London: Routledge & Kegan Paul.

    Chapter II. Kazimierz Twardowski and the Rise of the Analytical Movement in Poland, pp. 24-55.

  49. Smith, Barry. 1989. "Kazimir Twardowski: An Essay on the Borderlines of ontology, Psychology and logic." In The Vienna Circle and the Lvov-Warsaw School, edited by Szaniawski, Klemens, 313-373. Dordrecht: Kluwer.

  50. ———. 1994. Austrian Philosophy. The Legacy of Franz Brentano. Chicago: Open Court.

    See the Chapter: K asimir Twardowski: On content and object, pp. 160-195.

  51. ———. 2006. "Why Polish Philosophy Does Not Exist." In The Lvov-Warsaw School. The New Generation, edited by Jadacki, Jacek Jusliuz and Pasniczek, Jacek, 19-40. Amsterdam: Rodopi.

    "Why have Polish philosophers fared so badly as concerns their admission into the pantheon of "Continental philosophers?" Why, for example, should Heidegger and Derrida be included in this pantheon, but not Ingarden or Tarski? Why, to put the question from another side, should there be so close an association in Poland between philosophy and logic, and between philosophy and science? We distinguish a series of answers to this question, which are dealt with under the following headings: (a) the role of socialism; (b) the disciplinary association between philosophy and mathematics; (c) the influence of Austrian philosophy in general and of Brentanian philosophy in particular; (d) the serendipitous role of Twardowski; (e) the role of Catholicism. The conclusion of the paper is that there is no such thing as 'Polish philosophy' because philosophy in Poland is philosophy per se, it is part and parcel of the mainstream of world philosophy -- simply because, in contrast to French or German philosophy, it meets international standards of training, rigour, professionalism and specialization."

  52. Vasyukov, Vladimir L. 1998. "Non-Elementary Exegesis of Twardowski's Theory of Presentations." In The Lvov-Warsaw School and Contemporary Philosophy, edited by Kijania-Placek, Katarzyna and Wolenski, Jan, 153-167. Dordrecht: Kluwer.

    "In spite of the historical proximity of S. Leśniewski to K. Twardowski, ari attempt to look at Twardowski's heritage through Leśniewski's eyes leads to striking results. Firstly, it results in a wider framework than Leśniewski's Elementary Ontology and secondly, it involves a transition from Formal Ontology to Formai Phenomenology. In this paper an extension of Leíniewskis's Non-Elementary Ontology is presented which is suitable for investìgating Twardowski's Theory of Presentation."

  53. Vinogradov, Evgeni G. 1998. "The Rationalistic Paradigm of Franz Brentano and Kazimierz Twardowski." In The Lvov-Warsaw School and Contemporary Philosophy, edited by Kijania-Placek, Katarzyna and Wolenski, Jan, 101-104. Dordrecht: Kluwer.

  54. Wolenski, Jan. 1989. Logic and Philosophy in the Lvov-Warsaw School. Dordrecht: Kluwer.

  55. ———. 1992. "'Being' as a Syncategorematic Word: A Completion (?) of Twardowski's Analysis of 'Nothing'." In Theories of Objects: Meinong and Twardowski, edited by Pasniczek, Jacek, 75-85. Lublin: Wydawnictwo Uniwersytetu Marii Curie-Slodowskiej.

  56. ———. 1999. "Twardowski and the Distinction between Content and Object." Brentano Studien.Internationales Jahrbuch der Franz Brentano Forschung no. 8:15-36.

    "The content/object distinction was the main philosophical result achieved by Twardowski. However, he had predecessors. This paper discusses the development of the mentioned distinction from Bolzano to Twardowski. Views of Zimmermann, Brentano, Meinong, Höfler are taken into account; also some objections of Husserl against Twardowski are discussed and evaluated. The paper also stresses the general philosophical significance of Twardowski's work."

  57. ———. 2002. "From Intentionality to Formal Semantics (From Twardowski To Tarski)." Erkenntnis no. 56:9-27.

    "This paper intends to show that the rise of semantics in Poland was related to Kazimierz Twardowski and his understanding of mental acts as intentional (in Brentano's understanding plus the principally realistic conception of intentional objects). Twardowski's theory of language was consequently semantic considering words as products of mental acts and as referring to the world. This view was then refined by Twardowski's students, in particular Stanislaw Leśniewski and Tadeusz Kotarbinski. Both were teachers of Alfred Tarski, the founder of modern formal semantics. These facts suggest that the intentional conception of language was an important philosophical context of Tarski's work."

  58. ———. 2009. "The Rise and Sevelopment of Logical Semantics in Poland." In The Golden Age of Polish philosophy. Kazimierz Twardowski's Philosophical Legacy, edited by Lapointe, Sandra, Wolenski, Jan, Marion, Mathieu and Miskiewicz, Wioletta, 43-59. New York: Springer.


  1. Brandl, Johannes. 1996. "Kazimierz Twardowski uber Funktionen und Gebilde: Einleitung zu einem text aus dem Nachlass." Conceptus.Zeitschrift für Philosophie no. 24:145-156.

    "Among the unpublished writings of Kazimierz Twardowski so far there is an essay in which Twardowski tries to embed the concept of an intentional object' within a theory that comprises at the same time psychological, logical and grammatical aspects. This theory of actions' and products' is presented here and several applications of the theory are discussed. The central question thereby is whether the distinction between actions and products enables Twardowski to counter the objection of psychologism raised against him. Having explained Twardowski's position we describe from an editorial point of view the text in which his theory is transmitted. The text itself is published according to the given editorial principles after this introduction."

    [The text is: Funktionen und Gelbilde pp. 157-189]

  2. Brożek, Anna. 2012. Kazimierz Twardowski: die Wiener Jahre. Berlin: Springer.

  3. Chrudzimski, Arkadiusz. 2007. Gegenstandstheorie und Theorie der Intentionalität bei Alexius Meinong. Dordrecht: Springer.

    Inhaltverzeichnis: Einführung IX-XII; 1. Intentionalität und immanente Objekte. Die Lehre Franz Brentanos 1; 2. Abstraktion und Relationen. Der junge Meinong 53; 3. Inhalt und Gegenständ. Meinongs Lehre um 1900 103; 4. Die Lehre von den Objektiven (1902) 149; 5. Gegenstandstheorie (1904-1920) 179; 6. Meinongs Gegenstände und die intentionale Beziehung 251; 7. Meinong'sche "Konstitutionssysteme" 307; 8. Die Logik des Ausserseins 353; Schlusswort 371; Bibliographie 373; Namenverzeichnis 385-386

    3.1 Twardowski über Inhalt und Gegenstand der Vorstellungen (1894), pp. 104-115 and 3.2 Twardowski, Husserl und Meinong (1894-1904), pp. 116-127.

  4. Sebestik, Jan. 1989. "Nicht-existierende Gegenstände und strukturale Ontologie bei Twardowski." Grazer Philosophische Studien no. 35:175-188.

  5. Tanasescu, Ion. 1999. "Der Vorstellungsgegenstand. Zu Twardowskis Rezeption der Psychologie Brentanos." Brentano Studien.Internationales Jahrbuch der Franz Brentano Forschung no. 8:53-66.


  1. Benoist, Jocelyn. 1995. "À l'origine de la phénomenologie: au déla de la réprésentation." Critique:480-506.

  2. Betti, Arianna. 2005. "Propositions et états de choses chez Twardowski." Dialogue.Canadian Philosophical Review no. 44:469-492.

    "Twardowski's On the Content and Object of Presentations (1894) is one of the most influential works that Austrian philosophy has left to posterity. The manuscript Logik (1894-1895) supplements that work and allows us to reconstruct Twardowski's theory of judgment. These texts raise several issues, in particular whether Twardowski accepts propositions and states of affairs in his theory of judgment and whether his theory is acceptable. This article presents Twardowski's theory, shows that he accepts states of affairs, that he has a notion of proposition, and that his theory is interesting and sophisticated."

  3. Dambska, Izydora. 1978. "François Brentano et la pensée philosophique en Pologne: Casimir Twardowski et son École." Grazer Philosophische Studien no. 5:117-130.

  4. Fisette, Denis. 2003. "Représentations. Husserl critique de Twardowski." In Aux origines de la phénoménologie : Husserl et le contexte des Recherches logiques, edited by Fisette, Denis, 61-91. Paris: Vrin.

  5. Rusnock, Paul. 2007. "Qu'est-ce que la représentation? Bolzano et la philosophie autrichienne." Philosophiques no. 30:67-81.

    "Largely ignored in Germany during the nineteenth century, Bolzano was certainly better known in Austria, in particular among Brentano's students, who enthusiastically studied his Theory of Science. In this respect it makes sense to speak of Bolzano as belonging to a tradition of Austrian philosophy. Yet an examination of the reception of Bolzano's ideas among Brentano's students indicates that he was not always well understood. This article discusses a particular case, Twardowski's reaction to Bolzano's theory of representation."

  6. Sebestik, Jan. 1994. "Twardowski entre Bolzano et Husserl: la théorie de la représentation." Cahiers de Philosophie Ancienne et du Langage no. 1:61-85.

    "La plus importante des possibilités ainsi ouvertes consiste sans doute dans le réalisme de Twardowski, dans son orientation en direction de l’objet. L’ “étude psychologique” qui porte sur la représentation finit pas se constituer en une ontologie relationnelle de l’objet. Par delà les analyses psychologiques de l’objet intentionnel, Twardowski a intégré dans sa théorie deux doctrines essentielles de Bolzano : la méréologie, qui forme la base de son système mathématique, et la théorie de l’objet, le noyau de sa sémantique logique.

    Malgré la critique husserlienne des “deux faces qui donneraient à l’expression, l’une la signification, et l’autre la détermination de son orientation vers l’objet”, la séparation méthodique et le traitement indépendant du contenu et de l’objet de la représentation, ont permis à Twardowski d’accorder aux objets l’autonomie et l’indépendance nécessaires pour permettre à Tarski, disciple de Łukasiewicz, lui-même disciple de Twardowski, d'établir la sémantique logique."


  1. Besoli, Stefano. 1991. "La verità del contenuto. Riflessioni intorno alla problematica del giudizio in Twardowski." Discipline Filosofiche no. 2:49-94.

  2. Coniglione, Francesco. 1996. Nel segno della scienza. La filosofia polacca del Novecento. Milano: Franco Angeli.

    Kazimierz Twardowski e la fondazione della filosofia scientifica, pp. 79-89.

  3. Galewicz, Wlodimierz. 1991. "Tra psicologismo e platonismo. Osservazioni sulla teoria dei prodotti mentali di Twardowski." Discipline Filosofiche no. 2:95-116.

  4. Modenato, Francesca. 1984. "Atto, contenuto, oggetto: da F. Brentano a K. Twardowski." Verifiche no. 13:55-78.

  5. Olejnik, Roman. 1992. "Kazimierz Twardwski filosofo e fondatore." Aquinas.Rivista Internazionale di Filosofia no. 35:653-660.

    "The Scholar, who at the start of this century has indicated the direction towards philosophy not only of the School of Leopoli but, in a certain sense, of the whole Poland, was Kazimierz Twardowski. This study presents briefly his biography and his activity as teacher and as organiser. The knowledge of the setting in which he was formed in the intellectual attitude of the founder of the Philosophical School of Leopoli-Warsaw can facilitate a brief exposition of the theories of Twardowski. He was an excellent Brentanist, and in the development of this doctrine he stands midway between F. Brantano and E. Husserl. K. Tardowski is the founder of the School which represents a relevant trend in modern analytical philosophy."

Related pages

On the website "Theory and History of Ontology" (

Kazimierz Twardowski on the Content and Object of Presentations


Stanislaw Leśniewski's Logical Systems: Protothetic, Ontology, Mereology

Tadeusz Kotarbinski from Ontological Reism to Semantical Concretism

Roman Suszko and the Non-Fregean Logics

Roman Ingarden and the Realism/Idealism Debate

Bogusław Wolniewicz on the Formal Ontology of Situations

Jerzy Perzanowski: Modal Logics, Ontology and Ontologics