logical bob wrote:JamesSS wrote:In the Conceptual Realm, each concept affects the others. A straight line affects what a square is. A curve affects what a circle is. And it is all merely a matter of convenience of thought. Without the Conceptual Realm, how does one speak of an ideal circle that can never physically exist?
Alas, this is nonsense.
A circle is the set of points in the plane that are equidistant from a specified centre. It can be shown that a circle with radius r centred at (a,b) is the set of points (x,y) that satisfy
(x-a)2 + (y-b)2 - r2 = 0
and as such circles are a particular example of algebraic curves, a curve being a set of points satisfying an arbitrary polynomial equation.
Which can never physically exist.
logical bob wrote:To say that a curve "affects what a circle is" is hopelessly vague and woolly.
It isn't something that I would normally bother to say. It merely maintains the consistency of the concept of a realm of existence.
logical bob wrote:Suppose there was a set bigger than the set of integers yet smaller than the set of real numbers [easy to do]. That would have some serious implications, so I suppose that (if we could straighten out your idea of how one mathematical object affects another to get something coherent) you'd want to say that if affected other things, and therefore existed [within that realm]. The problem is that it doesn't exist. Using the normal mathematical rules it's impossible to prove or disprove the existence of such a set.
You seem to be ignoring yourself a little.
You say that such a set doesn't "exist". But then you immediately say that such a set cannot be proven to exist or not.
Proof is in the eyes of the beholder, so I'm not sure what logic you forbid such as to disallow such a proof. Do you disallow cardinalities of infinity, or hyperreal numbers? Those are issues of logic, thus I can't disallow them. Math is supposed to just be logic applied to quantities, but some people prefer to see it as merely a set of authorized chosen rules disregarding any association with logic, thus there might be a few holes that disallow completeness and proofs.
logical bob wrote:
How are you going to account for the difference between mathematical objects whose existence has consequences and mathematical objects whose existence would have consequences without a better criterion for determining which ones exist?
Any defined concept that isn't an oxymoron "exists" as a concept. The concept might be unusable in your application, but it would still exist as a concept. So I don't know to what you are referring. Any change in logical association creates consequences. So I don't see how you can have any mathematical set that can be altered and yet not cause logical consequence to everything else. If you declare that 2+2=3, you change all mathematics, not merely that one equation.
Sendraks wrote:Your explanation was clear, as opposed to the word salad I'm used to seeing in the philosophy forum, I'm grateful for that.
Well, thank you, but actually today I feel like I am struggling for words and rambling a bit.