From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/5289 Path: news.gmane.org!not-for-mail From: Charles Wells Newsgroups: gmane.science.mathematics.categories Subject: Re: categorical foundations Date: Mon, 16 Nov 2009 19:39:12 -0600 Message-ID: References: Reply-To: Charles Wells NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 X-Trace: ger.gmane.org 1258466011 32503 80.91.229.12 (17 Nov 2009 13:53:31 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 17 Nov 2009 13:53:31 +0000 (UTC) To: Colin McLarty , catbb Original-X-From: categories@mta.ca Tue Nov 17 14:53:23 2009 Return-path: Envelope-to: gsmc-categories@m.gmane.org Original-Received: from [138.73.1.1] (helo=mailserv.mta.ca) by lo.gmane.org with esmtp (Exim 4.50) id 1NAOUj-00014G-EA for gsmc-categories@m.gmane.org; Tue, 17 Nov 2009 14:53:21 +0100 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1NANqk-0000CD-Ge for categories-list@mta.ca; Tue, 17 Nov 2009 09:12:02 -0400 Original-Sender: categories@mta.ca Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:5289 Archived-At: This is the right attitude toward doing math. You can work away with the axioms for categories without caring about models of the axioms, unless you try to do certain things such as for example take a limit over all the diagrams of a certain kind in the category. Then you have to think about foundations. You can check what logical constructs you have used in a mathematical argument, and then maybe you will see you have not used the axiom of choice or excluded middle, so your models can live in many toposes. And so on. This is "just in time" foundations: think about foundations when you have to, not before. That is really what most of us do most of the time. Charles Wells On Mon, Nov 16, 2009 at 8:54 AM, Colin McLarty wrote: > > This is the Hilbert conception where axioms are not asserted as true > but offered as implicit definition; and so they are not about any > specific subject matter but may be applied to whatever satisfies them. [For admin and other information see: http://www.mta.ca/~cat-dist/ ]