{"id":1971,"date":"2009-12-13T18:17:24","date_gmt":"2009-12-13T17:17:24","guid":{"rendered":"http:\/\/emilkirkegaard.dk\/en\/?p=1971"},"modified":"2009-12-13T19:12:06","modified_gmt":"2009-12-13T18:12:06","slug":"identity-and-personal-identity","status":"publish","type":"post","link":"https:\/\/emilkirkegaard.dk\/en\/2009\/12\/identity-and-personal-identity\/","title":{"rendered":"Identity and personal identity"},"content":{"rendered":"

Some people think that the identity notion is captured by the second proposal above. I think we need two notions of identity. I will not discuss that now.<\/p>\n

Strict identity<\/h3>\n

For all things, for all things, for all predicates, that x and y are strictly identical logically implies that that x has predicate F is logically equivalent with that that y has predicate F.<\/p>\n

(\u2200x)(\u2200y)(\u2200F)(x=S<\/sub>y\u21d4(Fx\u21d4Fy)) [with obvious interpretation and =S <\/sub>meaning strict identity]<\/p>\n

This is called Liebniz’s law.<\/p>\n

Personal identity<\/h3>\n

Kennethamy:<\/p>\n

\u201cI think Liebniz’s law accommodates personal identity quite comfortably with the addition of a time quantifier: x and y are identical if any property possessed by x at time t is also possessed by y at time t. If you add a world quantifier it can also handle transworld identity rather well.\u201c<\/p>\n

For all things, for all things, for all predicates, for all times, that x and y are personally identical logically implies that that x has predicate F at time t is logically equivalent with that that y has predicate F at time t.<\/p>\n

(\u2200x)(\u2200y)(\u2200F)(\u2200t)(x=P<\/sub>y\u21d4(Fxt\u21d4Fyt)) [with obvious interpretation and =P <\/sub>meaning personal identity]<\/p>\n

This seems to work.<\/p>\n

But I don’t understand the part about transworld identity. It seems to me that the above can handle transworld identity fine.<\/p>\n","protected":false},"excerpt":{"rendered":"

Some people think that the identity notion is captured by the second proposal above. I think we need two notions of identity. I will not discuss that now. Strict identity For all things, for all things, for all predicates, that x and y are strictly identical logically implies that that x has predicate F is […]<\/p>\n","protected":false},"author":17,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1457],"tags":[1504,1507,1505,1506],"class_list":["post-1971","post","type-post","status-publish","format-standard","hentry","category-metaphysics","tag-identity","tag-liebnizs-law","tag-personal-identity","tag-strict-identity","entry"],"_links":{"self":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts\/1971","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/users\/17"}],"replies":[{"embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/comments?post=1971"}],"version-history":[{"count":2,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts\/1971\/revisions"}],"predecessor-version":[{"id":1973,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts\/1971\/revisions\/1973"}],"wp:attachment":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/media?parent=1971"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/categories?post=1971"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/tags?post=1971"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}