{"title":"‘Everything True Will Be False’: Paul of Venice and a Medieval Yablo Paradox","authors":"S. Read","doi":"10.1080/01445340.2022.2040797","DOIUrl":null,"url":null,"abstract":"In his Quadratura, Paul of Venice considers a sophism involving time and tense which appears to show that there is a valid inference which is also invalid. Consider this inference concerning some proposition A : A will signify only that everything true will be false, so A will be false. Call this inference B . A and B are the basis of an insoluble-that is, a Liar-like paradox. Like the sequence of statements in Yablo's paradox, B looks ahead to a moment when A will be false, yet that moment may never come. In the Quadratura, Paul follows the solution to insolubles found in the collection of elementary treatises known as the Logica Oxoniensis, which posits an implicit assertion of its own truth in insolubles like B . However, in the treatise on insolubles in his Logica Magna, Paul develops and endorses a different solution that takes insolubles at face value. We consider how both types of solution apply to A and B : on both, B is valid. But on one, B has true premises and false conclusion, and contradictories can be false together; on the other (following the Logica Oxoniensis), the counterexample is rejected.","PeriodicalId":55053,"journal":{"name":"History and Philosophy of Logic","volume":"43 1","pages":"332 - 346"},"PeriodicalIF":0.5000,"publicationDate":"2022-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"History and Philosophy of Logic","FirstCategoryId":"98","ListUrlMain":"https://doi.org/10.1080/01445340.2022.2040797","RegionNum":3,"RegionCategory":"哲学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"HISTORY & PHILOSOPHY OF SCIENCE","Score":null,"Total":0}
引用次数: 0
Abstract
In his Quadratura, Paul of Venice considers a sophism involving time and tense which appears to show that there is a valid inference which is also invalid. Consider this inference concerning some proposition A : A will signify only that everything true will be false, so A will be false. Call this inference B . A and B are the basis of an insoluble-that is, a Liar-like paradox. Like the sequence of statements in Yablo's paradox, B looks ahead to a moment when A will be false, yet that moment may never come. In the Quadratura, Paul follows the solution to insolubles found in the collection of elementary treatises known as the Logica Oxoniensis, which posits an implicit assertion of its own truth in insolubles like B . However, in the treatise on insolubles in his Logica Magna, Paul develops and endorses a different solution that takes insolubles at face value. We consider how both types of solution apply to A and B : on both, B is valid. But on one, B has true premises and false conclusion, and contradictories can be false together; on the other (following the Logica Oxoniensis), the counterexample is rejected.
期刊介绍:
History and Philosophy of Logic contains articles, notes and book reviews dealing with the history and philosophy of logic. ’Logic’ is understood to be any volume of knowledge which was regarded as logic at the time in question. ’History’ refers back to ancient times and also to work in this century; however, the Editor will not accept articles, including review articles, on very recent work on a topic. ’Philosophy’ refers to broad and general questions: specialist articles which are now classed as ’philosophical logic’ will not be published.
The Editor will consider articles on the relationship between logic and other branches of knowledge, but the component of logic must be substantial. Topics with no temporal specification are to be interpreted both historically and philosophically. Each topic includes its own metalogic where appropriate.