Can Any Two Things Be Identical???

Alan; I am sure you mean that everything changes in time so that nothing equals its previous being, and this is true... But how could you find your way home if not to the identical number and address you left??? Have you ever seen identical twins look, or act alike??? Identity does not mean equality except in the most general sense of a river being the same river in spite of gross inequalities...

Phenomenologically speaking, identity, which is an essential principal of reason, and reasoning, also prevents our seeing each thing, each river as new, and finding ourselves as new each day and hour... Yet, we must live in the real world, and we cannot spend all our time in a confusion of new names and new experiences of everything... Just remember that everything, for the most part is the same in the act of change... Every element is radioactive with extremely long half lives, for an example... life is change...

The only thing that stops me thinking there are no two identical objects in the universe is that it's awfully difficult in an infinite universe to declare anything beyond possible.

My understanding of maths suggests that x=x only by common conscent of any two mathematicians for a given purpose, (and even then the point may well be to prove otherwise.)
Let x=x.

That is an excellent point. The universe being infinite does not mean that it is possible that two infinite universes exist at the same time, which is the only way that I can see two things being identical. And still, that would not even be true due to the multiple dimension argument I previously posted. Still, excellent line of thought.

A Lyn

I'm afraid I can't answer that question until you can assure me that our shared meaning of the word "identical" is exactly the same.

I've read several of the responses to this question, and some are better than I can give. My only responses was to say that two things cannot have the same location although location is a necessary property of "things" in space-time. I rather like the response someone has given that we must ignore this property of location if your question is to be of any value to you. If we may ignore location and other similar extraneous properties such as angular momentum, and just address the internal physical properties of two seemingly identical physical objects, the question seems easier, but are we allowed to focus our response on such physical "things" without regard to unphysical properties they may have (like consciousness, mind, emotion, soul, etc.), and without regard to transitional events they may be undergoing--one might be reacting to higher local radiation than the other, one might be in a greater gravity well, etc.? May we then consider our two "things" in the abstract, removed from their environment?

If so, then I see no reason why two "things" cannot be identical in all observable and measurable properties, except as has been mentioned, that they remain TWO distinct objects. (Mama says, "Don't touch that thing, Henry! Lord knows where it may have been.") But why cannot two atoms be identical in all the properties of which we may have knowledge, and perhaps also in all those of which we have no knowledge? Here, I think, is where you really decide what you mean by the words, "two" and "things" and "identical". It is possible to define every no response into a yes, and every yes response into a no.

Good job, all!
Samm

This one reminds me. All mosquitoes and all flies are identical. They are all horrible, disgusting, blood-sucking, vomiting, filthy, (did I say disgusting?), wretched, repulsive, yucky, ichy, insidious demons from hell. I believe this incorporates all the cogent properties of their species.

Samm

Yes, Mark.

Two instances of the number "4"" are identical to one another (if space-time, a human invention, is disregarded.)

You might be interested in this: In the Roman view of the afterlife, if a person was not intered properly, their spirits became evil, that is: Larve...

The Ontological Argument relies on the idea that no two things can be identical.

It also calls into my mind the Hyalean Theoric World theorem advanced by Neal Stephenson.

Cycloptichorn

but not for hygrogen being just simply hygrogen

hygrogen atom in it simplest form , is indentical with a hygrogen atom also in its simplest form

can a hygrogen atom, in it's simplest form, be alone?

sure

Come on guys... Identity is a principal upon which all reasoning is based... It does not have the meaning of any exact equality... A cat is a cat. .. A is A... A line is a line... Is something wrong with your heads???... Don't be towels...

People assume they are all same until they get to know them. Some of my best friends are hydrogen atoms, and there's good and bad in em just like regular folks.
Seriously, I don't think the atoms are identical, even if, for practical purposes, they can be assumed to be.

5.53 Identity of object I express by identity of sign, and not by using a sign of identity. Difference of object I express by difference of sign.

Wittgenstein seems to agree with you.

imo,
If the names of the values of variables, are unique and referring to unique objects, then, only (a=a), (b=b), (c=c) etc., are true.
That is, a=b or a=c etc., are false. Because, the name a is different from the name b. ie. it must refer to a different unique object.
This shows the very limited use of formal identity.

Another problem with identity is that; x=x -> [](x=x) and x=y -> [](x=y), are theorems.
That is, there are no contingent identities, and consequently, there are no contingent existences.

But, when we use descripions, identity is required.
(the morning star = Venus) and (the evening star = Venus), implies,
(the morning star = the evening star) ...is sensible and true.

a=a, is not informative, but, (the x such that Fx) = a, is informative.

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Hi Guys,
I am referring to physical things, and physical things, ONLY.
Someone wrote that two number 4's are identical... The number 4 is not a physical thing, nor is an inch, a mile, a fathom, a metre, a week, a year or any kind of measurment.

And what the blue blazes is HYGROGEN?
Hygro; Gk - Moisture (comb of wet and moist).

I can forgive mis-spellings, but not when 7 of you are doing it. That borders on obscene.

As for the "infinity" conclusions; Whereas the universe is infinite, and this removes the possibility of other universes. What the heck are you talking about? If infinity is, indeed, effective - There would be an infinite amount of Big-bangs - This conflicts with your suggestion on the principle that - it does.

Anyway, thank you all for your replies, and have a lovely day.
Mark...

Same as two embryos in utero.

Hi Miller,
Nice to meet you.
Exactly!

Best wishes.
Mark...

How can this be, when their strands of DNA are constantly undergoing spontaneous mutations?

Hi, Miller! Guess you know my mosquito & fly response was a joke. They all identical in being the spawn of hell!

Samm

P.S. Do you know how I can get this "phil" thing off my name?