Modal logic is currently one of the most active areas of logic research.
Logic has a long-standing tradition of distinguishing valid from invalid inferences.
In logic research, inferences are studied formally, that is, logicians abstract away from the particularities of specific inferences in natural language and focus instead on the general logical pattern of the inferences. Modal logic concerns the systematical study of inferences with sentences containing ‘modalities’ (modal concepts).
Different branches of modal logic study the logical behavior of different modalities, such as alethic modalities like ‘It is possible that A’ and ‘It is necessary that A’, epistemic modalities like ‘Agent a knows that A’ and ‘Agent a believes that A’, deontic modalities like ‘It is obligatory that A’ and ‘It is permitted that A’, and temporal modalities like ‘It was the case that A’ and ‘It will be the case that A’.
Today there is a rich gamut of modal logics, providing a thorough understanding of phenomena in fields as diverse as mathematics, computer science, artificial intelligence, law, ethics, linguistics, and philosophy. Obviously, like any other human endeavor, modal logic has a history.
All too often, however, the history of modern modal logic is presented as an American success story that started with the work of the Harvard philosopher Clarence Irving Lewis (1918; 1932), while prewar modal logic research in Europe is passed off as a side-show of well-intended failures.
One of the principal aims of the project “Modal logic and Austrian-Polish philosophy”” is to correct this picture. Another one is to exploit these ideas to open up unexpected paths of development in contemporary modal logic research.
The starting point of the project are the key works on modal logic in prewar continental Europe: Jan Łukasiewicz's ‘O logice trójwartościowej’ (1920), Ernst Mally’s Grundgesetze des Sollens (1926), and Oskar Becker’s ‘Zur Logik der Modalitäten’ (1930).
I reconstruct the debates on metaphysics, the foundations of ethics, and the philosophy mathematics to which the mentioned authors contributed with their works, thus firmly embedding their logical systems in the philosophical and logical literature of the 1920s and 1930s
I put these texts in perspective by tracing their conceptions back to their most important sources of inspiration, in particular Bernard Bolzano, and present an in-depth account of Bolzano’s Theory of Absolute and Relative Modalities.
I show how a number of seemingly old-fashioned and rough ideas emerging from prewar modal logic have instead a great potential to give new impulse to contemporary research in modal logic.
I make the key texts of European prewar modal logic easily accessible by publishing volumes with English translations, historical introductions and detailed annotations. (Mally’s Grundgesetze des Sollens and Becker’s ‘Zur Logik der Modalitäten’ have bis dato never been translated into any other language.)
The realization of the project will make a strong impact both on the history of logic and on various areas of present-day modal logic.