{"id":5883,"date":"2017-01-08T11:35:29","date_gmt":"2017-01-08T11:35:29","guid":{"rendered":"https:\/\/maverickphilosopher.blog\/index.php\/2017\/01\/08\/another-round-with-the-opponent-on-the-necessity-of-identity\/"},"modified":"2017-01-08T11:35:29","modified_gmt":"2017-01-08T11:35:29","slug":"another-round-with-the-opponent-on-the-necessity-of-identity","status":"publish","type":"post","link":"https:\/\/maverickphilosopher.blog\/index.php\/2017\/01\/08\/another-round-with-the-opponent-on-the-necessity-of-identity\/","title":{"rendered":"Another Round With the Opponent on the Necessity of Identity"},"content":{"rendered":"

The Opponent writes<\/a>,<\/span><\/p>\n

The Maverick Philosopher has a comment<\/a> on my earlier question about the necessity of identity. Can we get from \u2018a=b\u2019 to \u2018necessarily a=b\u2019 in a simple step? He thinks we can.<\/span><\/p>\n

\n

Now if \u2018H\u2019 and \u2018P\u2019 designate one and the same entity, then what appears to be of the form a = b<\/em>, reduces to the form a = a<\/em>. Clearly, if a = a, then necessarily, a = a. The assumption that the identity of H with P is contingent entails the absurdity that a thing is distinct from itself. Therefore the relation denoted by \u2018=\u2019 holds necessarily in every case in which it holds. Q. E. D.<\/span><\/p>\n<\/blockquote>\n

The problem is the claim that \u2018H\u2019 (\u2018Hesperus\u2019) and \u2018P\u2019 (\u2018Phosphorus\u2019) designate one and the same entity<\/em>. How do we get there, given only<\/em> that H is the same object as P? Suppose we grant that H and P are this \u2018one and the same entity\u2019. We are saying that there is some entity, call it \u2018V\u2019 (i.e. Venus), such that H is identical with V and P is identical with V. Fair enough. But how do we get from there to the claim that the names designate<\/em> this one and the same entity, i.e. that \u2018H\u2019 designates V and \u2018P\u2019 designates V? I.e. what validates the move from 2 to 3 in the following argument?<\/span><\/p>\n

1. H=V<\/span>
2. \u2018H\u2019 designates H<\/span>
3. Therefore \u2018H\u2019 designates V.<\/span><\/p>\n

You need the principle of substitutivity, the principle that if a=b and Fa, then infer Fb. For example, let F be the function \u2018\u2018H\u2019 designates \u2013\u2019. Then we agree that F(H), because we assumed that \u2018H\u2019 designates H. And we posit that H=V. Given substitutivity, it follow that F(V). But only<\/em> given that substitutivity is valid in this case<\/em>, which is not at all obvious, at least to me.<\/span><\/p>\n

RESPONSE<\/span><\/p>\n

I am afraid I just don't understand what the Opponent's problem is.  He writes, "The problem is the claim that \u2018H\u2019 (\u2018Hesperus\u2019) and \u2018P\u2019 (\u2018Phosphorus\u2019) designate one and the same entity<\/em>. How do we get there, given only<\/em> that H is the same object as P?"  Apparently, the Opponent wants to know what validates the inference from<\/span><\/p>\n

\n

Hesperus is the same entity as Phosphorus<\/span><\/p>\n<\/blockquote>\n

to<\/span><\/p>\n

\n

'Hesperus' and 'Phosphorus' designate the same entity.<\/span><\/p>\n<\/blockquote>\n

What validates the inference is the principle that if two putatively distinct entities are in fact numerically the same entity, then the names for these putatively distinct entities are co-referential: they designate one and the same entity.<\/span><\/p>\n

I don't see the need to invoke a principle of substitutivity.  In the above inference there was no substitution of a name for a name.<\/span>  <\/span> <\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

The Opponent writes, The Maverick Philosopher has a comment on my earlier question about the necessity of identity. Can we get from \u2018a=b\u2019 to \u2018necessarily a=b\u2019 in a simple step? He thinks we can. Now if \u2018H\u2019 and \u2018P\u2019 designate one and the same entity, then what appears to be of the form a = … Continue reading “Another Round With the Opponent on the Necessity of Identity”<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[346,408],"tags":[],"class_list":["post-5883","post","type-post","status-publish","format-standard","hentry","category-identity-and-individuation","category-language-philosophy-of"],"_links":{"self":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/posts\/5883","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/comments?post=5883"}],"version-history":[{"count":0,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/posts\/5883\/revisions"}],"wp:attachment":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/media?parent=5883"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/categories?post=5883"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/tags?post=5883"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}