I am aware of sometimes not making my thoughts clear in posting.
You expressed your position perfectly clearly. It's consistent with the philosophical doctrine of ultrafinitism.
It's like if I came to a philosophy forum and I said, "I believe there are two types of things: the physical, and the mental. Both of these things exist and they are different."
If I said that, someone would point out that I'm simply expressing what's known as Cartesian dualism. If I then said, "Oh no you're just labelling me," that would be inaccurate. I may not have studied Cartesian dualism formally, but that is simply the name for the belief that there are two kinds of substance: mind and matter.
Likewise, if you believe that a number can be said to exist if it can be instantiated in the real world; and otherwise it can't be said to exist; that's pretty close to ultrafinitism. It's a perfectly sensible view, its only drawback is that it's hard to get science off the ground without infinitary math. [That in itself has philosophical implications. WHY is physics based on infinitary math when we all agree that there are no actual infinities in the real world? Conversation for another time, and an interesting one].
A Peano type algorithm provides the potential to form integers of any desired magnitude. When formed they become real manifestations.
That's a nonstandard view of what the Peano axioms (not algorithm) are. When you take the successor of a number, that does not bring the successor into existence or make it a "real manifestation." The Peano axioms just show that we can formalize our intuition of the natural numbers by writing down a small number of perfectly plausible axioms. Although the induction axiom is NOT perfectly plausible at all. How can you "keep going forever" in a finite universe? That's where the ultrafinitists come in. They cast doubt on the inductive axiom of Peano.
The concept of 'infinite' resides in the mind only, and has no corresponding physical representation. It's easy to write 10^6 light yr, but no one can imagine it since it's so far removed from human experience.
Ok, perfectly agreed. Although I'd say that the number 3 resides in the mind only as well, but that's a side issue.
The thesis you are making is this: A number can claim to "exist" if it can be instantiated in the real world. A number that "has no corresponding physical representation," as you say, does NOT have a claim to existence.
That's ultrafinitism. You are saying that the number 3 exists because I can instantiate 3 in the real world, as in three chairs or three apples. But then what do we make of a number like $$2^{2^{2^{2^{2}}}}$$? This expression represents a number that is far larger than the number of atoms in the universe. The number denoted by this expression could never exist in the real world.
In the standard philosophy of math, that number exists every bit as much as 3 does. To an ultrafinitist, it's not actually well-defined. The way ultrafinitsts put this is that "Exponentiation is not a total function." In other words exponentiation does not always give a sensible answer given arbitrary inputs. If we wanted to count upward by 1's till will got to my expression, how would we know exactly when to stop? It's a good question actually.
If you are saying that numbers exist only to the extent that they can be instantiated in the real world, that is the position of the ultrafinitists.
I hope you don't think I'm making a criticism. Ultrafinitism is a perfectly valid philosophy of math. It just doesn't happen to be useful in getting modern math off the ground, let alone physical science.
In physics, a theory may predict a particle x, but unless it is discovered, it remains hypothetical or non existent.
Right. Just like ultrafinitism. But in standard math, a number exists when the axioms say it exists. Modern math accepts the axiom of infinity, so infinite sets exists.
Of course nobody is saying that infinite sets have
physical existence. Nor does math say that a set containing 3 elements has physical existence! Only that we can represent it within set theory.
No one will ever see an infinite list of integers, since by definition it has no end.
True. You're making an ultrafinitist argument. You're saying that an infinite set doesn't exist because we'll never see one in front of us. You are absolutely correct about that. That's why ultrafinitism is perfectly sensible. It's just not useful, because we can't do any modern math with it.
No one will ever see the value of pi, only an approximation.
Yes, that's also the point. Nobody will ever see any of the noncomputable numbers (these are the real numbers whose digits can not be cranked out by any algorithm). Nobody will ever see $$2^{2^{2^{2^{2}}}}$$.
If you accept the existence of these numbers because their abstract, mathematical existence can be proved from the standard axioms of math, that makes you a "standardist." I don't think there's a name for it. Perhaps "infinitarist."
If you deny that a number exists if that number can't be represented in the world, you're an ultrafinitist.
There's an intermediate position. A finitist believes in each of the counting numbers 1, 2, 3, 4, ... individually, but not all of them taken together as a set. In other words they accept the existence of the numbers given to us by the Peano axioms, but not the axiom of infinity.
What does that mean? Large compared to what?
You said the Peano axioms don't give us infinite integers. I was agreeing with you.
You can classify me in whatever group you like.
I'm only pointing out that you are expressing the perfectly legitimate beliefs of the philosophy of ultrafinitism. Just like if I say there are two substances, mind and matter, I'm expressing the beliefs of Cartesian dualism, even if I've never heard it put that way.
"That IS the point. Zero as a placeholder means there are no units in its location.
Here you're using zero as a numeral in a positional system of notation. Regardless, if you are arguing against the existence of the number zero, again that's not wrong, it just puts your mathematical thinking back in the middle ages somewhere. Being modern doesn't make us right. I'm not saying you're wrong, only that you are rejecting almost the entirety of modern math.
Dictionary meaning: without quantity or magnitude."
If you quoted from a math book that would be more compelling evidence.
Doesn't my quote say the same thing as your quote? Isn't 0 in number theory the same as {} in set theory?
Yes, {} is the way we represent the number 0 within set theory. They are not the "same" in the sense that 0 is an abstract number, and {} is merely its representation or definition in the formal system of set theory. One is an abstract thing, the other its representation.
It's not a quantity but an absence of quantity, just as dry is an absence of moisture.
It's a minor semantic point, but a mathematician would say, "Zero is not nothing!" For example the real number zero is a
particular location on the number line. If you're at coordinate 0 or you're at coordinate 47, you're still somewhere. A real number is just a label for a location.
The empty set {} has no members!
Correct. It's the set of all the purple flying elephants.
A good dictionary can provide an accurate definition of a word within a given field of study
Well you have only quoted from "the dictionary" but you have not specified whether you are using a good dictionary or not. Regardless, if you want the technical meaning of a word, you need to refer to the technical literature and not a general purpose dictionary. I don't know why you're arguing this point. When you go to medical school they hand you an anatomy text, not the Oxford unabridged dictionary.
, and the word origin which clarifies the meaning. I don't argue against sets, just the role of {}.
Ah, you're arguing against the empty set. Well you're not alone. One can make many substantive philosophical criticisms of set theory, and the nonsensical notion of the "empty set" is surely one of them.
I myself don't argue for the physical reality of the empty set. I tend to agree with you on this point.
However, we DO have to accept the existence of the empty set within the formal system of set theory, because the existence of the empty set can be proved from the axioms of set theory. One need not accept set theory; but one does at least have to agree that within set theory, the empty set exists.
There's another philosophical doctrine of interest, mathematical fictionalism, which says that our mathematical entities are fictions much as are the characters in a novel.
https://plato.stanford.edu/entries/fictionalism-mathematics/