{"id":38436,"date":"2017-01-31T03:57:39","date_gmt":"2017-01-31T08:57:39","guid":{"rendered":"http:\/\/trinities.org\/blog\/?p=38436"},"modified":"2017-03-04T11:01:28","modified_gmt":"2017-03-04T16:01:28","slug":"do-we-need-identity","status":"publish","type":"post","link":"https:\/\/trinities.org\/blog\/do-we-need-identity\/","title":{"rendered":"Do we need identity?"},"content":{"rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-38434 size-medium\" src=\"http:\/\/trinities.org\/blog\/wp-content\/uploads\/AB_testing_21-300x192.png\" width=\"300\" height=\"192\" srcset=\"https:\/\/trinities.org\/blog\/wp-content\/uploads\/AB_testing_21-300x192.png 300w, https:\/\/trinities.org\/blog\/wp-content\/uploads\/AB_testing_21-768x491.png 768w, https:\/\/trinities.org\/blog\/wp-content\/uploads\/AB_testing_21-1024x655.png 1024w, https:\/\/trinities.org\/blog\/wp-content\/uploads\/AB_testing_21-880x563.png 880w, https:\/\/trinities.org\/blog\/wp-content\/uploads\/AB_testing_21.png 1470w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/p>\n<p>A propos of a <a href=\"http:\/\/maverickphilosopher.typepad.com\/maverick_philosopher\/2017\/01\/nominalism.html\">discussion<\/a> going on at the Maverick Philosopher\u2019s place, I revisited \u2018Do we need Identity\u2019, chapter 6 of <i>The Logic of Natural Language<\/i>, a work by the late Fred Sommers that should be on everyone\u2019s bookshelf. As the title suggests, Sommers questions the doctrine of \u2018relationism\u2019, i.e. the view that identity is a relation, and that the verb \u2018is\u2019 functions both to connect subject and predicate, as in \u2018Venus <i>is<\/i> a planet\u2019, and to relate objects, as in \u2018Hesperus <i>is<\/i> Venus\u2019.<\/p>\n<p>I summarise his argument as follows. First, the distinction between the \u2018is\u2019 of predication and the \u2018is\u2019 of identity is not obvious, otherwise philosophers would have spotted it earlier. It is sometimes attributed to Leibniz, but Sommers questions whether it is to be found in that philosopher\u2019s writings. Second, it only seems obvious after we have accepted the category distinction made by modern logic between object words and concept words. If we agree that \u2018Venus\u2019 and \u2018Hesperus\u2019 must be represented in the syntax of modern logic by lower-case letters, we must represent them as \u2018a\u2019 and \u2018b\u2019. But then \u2018a is b\u2019 is ill-formed if we read the \u2018is\u2019 as the \u2018is\u2019 of predication. In the aptly named \u2018predicate logic\u2019, the verb \u2018to be\u2019 is swallowed up into the predicate: we must represent \u2018Venus is a planet\u2019 as \u2018Fa\u2019, where \u2018F\u2019 stands for \u2018is a planet\u2019. As Sommers ironically comments<\/p>\n<blockquote><p>It is <i>therefore<\/i> obvious that \u2018a is b\u2019 has the form F(a,b,) where F is the grammatical predicate which represents \u2018is identical with\u2019 or \u2018is no other than\u2019. Clearly, it is only after one has adopted the syntax that prohibits the predication of proper names that one is forced to read \u2018a is b\u2019 dyadically and to see in it a sign of identity.<\/p><\/blockquote>\n<p>It may still be objected that identity really is a relation, and that the modern syntax makes explicit what was there all along, but more of that later.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Sommers questions the doctrine of \u2018relationism\u2019, i.e. the view that identity is a relation&#8230;<\/p>\n","protected":false},"author":6,"featured_media":38434,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","footnotes":""},"categories":[10,9],"tags":[],"class_list":["post-38436","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-logic","category-philosophy"],"_links":{"self":[{"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/posts\/38436","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/comments?post=38436"}],"version-history":[{"count":4,"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/posts\/38436\/revisions"}],"predecessor-version":[{"id":38519,"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/posts\/38436\/revisions\/38519"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/media\/38434"}],"wp:attachment":[{"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/media?parent=38436"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/categories?post=38436"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/trinities.org\/blog\/wp-json\/wp\/v2\/tags?post=38436"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}