In modern times the so?called consequentia mirabilis (if not-P, then P). then P) was first enthusiastically applied and commented upon by Cardano (1570) and Clavius (1574). Of later passages where it occurs Saccheri?s use (1697) has drawn a good deal of attention. It is less known that about the middle of the 17th century this remarkable mode of arguing became the subject of an interesting debate, in which the Belgian mathematician Andreas Tacquet and Christiaan Huygens were the main representatives of (...) opposite views concerning its probative force. In this article the several phases and moves of that debate are delineated. (shrink)

In the first half of the 17th century the Aristotelian view that the same statement or belief may be true at one time and false at another and, on the other hand, the conception of a mental proposition as a fully explicit thought that lends a definite meaning to a declarative sentence originated a lively debate concerning the question whether a mental proposition can change its truth-value.In this article it is shown that the defenders of a negative answer and the (...) advocates of a positive answer argued on the basis of different notions of what a mental proposition is:one side taking it as more or less equivalent to a specific utterance?meaning and the other side as more or less equivalent to a generic sentence-meaning. (shrink)

Paperback. The intention of this book is to set forth the history (up to the end ofthe 17th Century) of logical and rhetorical reflections on dilemmaticarguments, i.e. arguments in which from each member of an exhaustivedisjunction of premisses an identical conclusion is drawn. Certain types ofsuch arguments were widely discussed among ancient teachers of rhetoricand, to a lesser extent, by ancient logicians. After a period of relativeneglect in the Middle Ages, there was a remarkable revival during theRenaissance. In the 17th (...) Century, several attempts were made to find theproper logical form of dilemmatic reasonings. In the course of tracingthese developments, special attention is paid to the consequentiamirabilis, a kind of argument in which a conclusion is inferredfrom a premiss that is its direct contradictory. (shrink)

1. Het eigene der wijsbegeerte.--2. Wijsbegeerte en geldigheid.--3. Wijsgerige interpretatie en reïnterpretatie.--4. Taalwetenschap en wijsbegeerte.--5. Taal en intersubjectiviteit.--6. Taalperspectivisme.--7. Regels en regelmaat.--8. Taaldaden.--9. Verwijzen en beweren.--10. De dragers van logische relaties.--11. Het Mentaals, de taal van het denken.--12. Taaluiting en logische structuur.