{"title":"External World Skepticism and Transcending the Everyday World","authors":"Toshihiro Ohishi","doi":"10.4216/jpssj.54.1_51-1","DOIUrl":"https://doi.org/10.4216/jpssj.54.1_51-1","url":null,"abstract":"","PeriodicalId":301300,"journal":{"name":"Kagaku Tetsugaku","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126781945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
At the end of the 19th century, the Peano School elaborated its famous theory of “definitions by abstraction”. Two decades later, Hermann Weyl elaborated a generalization of the former, termed “creative definitions”, capable of covering various cases of ideal elements (Peano’s abstracta being among them). If the Peano School proposal eventually appeared to be based on the nowadays standard classificatory process of quotienting a set by an equivalence, Weyl’s proposal still lacks a set-theoretical, classificatory interpretation. In this paper, we define and investigate the notion of relational indiscernibility (upon which Weyl’s creative definitions are based) and show that a bridge from the concept of indiscernibility to the notion of type (sets closed by bi-orthogonal) may be built from the observation that individuals are indiscernible exactly when they belong to exactly the same types. In the last part, we investigate some philosophical consequences of those observations concerning the theory of abstraction.
{"title":"From abstraction and indiscernibility to classification and types:","authors":"J. Joinet, T. Seiller","doi":"10.4216/JPSSJ.53.2_65","DOIUrl":"https://doi.org/10.4216/JPSSJ.53.2_65","url":null,"abstract":"At the end of the 19th century, the Peano School elaborated its famous theory of “definitions by abstraction”. Two decades later, Hermann Weyl elaborated a generalization of the former, termed “creative definitions”, capable of covering various cases of ideal elements (Peano’s abstracta being among them). If the Peano School proposal eventually appeared to be based on the nowadays standard classificatory process of quotienting a set by an equivalence, Weyl’s proposal still lacks a set-theoretical, classificatory interpretation. In this paper, we define and investigate the notion of relational indiscernibility (upon which Weyl’s creative definitions are based) and show that a bridge from the concept of indiscernibility to the notion of type (sets closed by bi-orthogonal) may be built from the observation that individuals are indiscernible exactly when they belong to exactly the same types. In the last part, we investigate some philosophical consequences of those observations concerning the theory of abstraction.","PeriodicalId":301300,"journal":{"name":"Kagaku Tetsugaku","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132671411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The issue of (in)compatibility between presentism and time travel has intrigued many philosophers for the last few decades. Keller and Nelson [2001] have argued that, if presentism is a feasible theory of time that applies to ordinary (non-time travel) cases, then it should be compatible with time travel. Bigelow [2001] and Sider [2005], on the other hand, have independently argued that the idea of time travel contradicts the presentist conception of time because it involves the (cid:98) spatialisation of time (cid:96) (in a metaphysical sense), which is something that presentists should resist. In support of the latter claim, I offer a new argument via a different route. More specifically, I clarify basic components of the view that I take as (cid:98) orthodox (cid:96) presentism by examining how presentists have considered temporal notions of the existence of things and their property possession. It is because of these notions that presentists can sensibly maintain a dynamic theory of time and should not believe in time travel.
{"title":"Presentists Should Not Believe in Time Travel","authors":"T. Sakon","doi":"10.4216/JPSSJ.53.2_191","DOIUrl":"https://doi.org/10.4216/JPSSJ.53.2_191","url":null,"abstract":"The issue of (in)compatibility between presentism and time travel has intrigued many philosophers for the last few decades. Keller and Nelson [2001] have argued that, if presentism is a feasible theory of time that applies to ordinary (non-time travel) cases, then it should be compatible with time travel. Bigelow [2001] and Sider [2005], on the other hand, have independently argued that the idea of time travel contradicts the presentist conception of time because it involves the (cid:98) spatialisation of time (cid:96) (in a metaphysical sense), which is something that presentists should resist. In support of the latter claim, I offer a new argument via a different route. More specifically, I clarify basic components of the view that I take as (cid:98) orthodox (cid:96) presentism by examining how presentists have considered temporal notions of the existence of things and their property possession. It is because of these notions that presentists can sensibly maintain a dynamic theory of time and should not believe in time travel.","PeriodicalId":301300,"journal":{"name":"Kagaku Tetsugaku","volume":"259 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123089644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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