Incidentally, Reid, I know I've treated you like trash on this topic, but since this is the "computer science and math stuff" thread, I would love to interest you in this post I made on somewhat the same matter at hand, in this very thread. I know that since I am not in a grad program, I am indeed a "pip squeak" before the collective intelligentsia of mathematics establishment as it exists today, but: from what I've gleaned from those greater than myself, I've come to appreciate what apparently is a minority view among mathematicians (although among the more problem solving oriented mathematicians I've interacted with, it is not quite as controversial a perspective to have as Cartier might seem to suggest). It's not necessarily in conflict with the majority view, either, but simply another angle to look at things, although I hope it might upset the degree of philosophical certainty through which you view the matter.
Anyway, I've quoted the interesting passage from the beginning of this very interesting essay by Pierre Cartier. Of course I don't want to appear the insecure name dropper desperate for approval, a la Koobie, which you've tacitly taken me for once I had provoked you into doing so, but: I honestly think what Cartier has to say is quite convincing (and the remainder of the paper is quite fascinating in content as well). I've tried to more or less take inspiration from it, at least in spirit, in everything I work on (which is admittedly mostly outside of mathematics, per se). Finally, I will mention that just looking at who the paper is dedicated to is a big hint about the aesthetic being depicted here.
(Emphasis in the original.)
[quote=Pierre Cartier]
To the memory of Gian-Carlo Rota,
modern master of mathematical magical tricks
[...]
The implicit philosophical belief of the working mathematician is today the
Hilbert-Bourbaki formalism. Ideally, one works within a closed system:
the basic principles are clearly enunciated once for all, including (that is an
addition of twentieth century science) the formal rules of logical reasoning
clothed in mathematical form. The basic principles include precise defini-
tions of all mathematical objects, and the coherence between the various
branches of mathematical sciences is achieved through reduction to basic
models in the universe of sets. A very important feature of the system is its
non-contradiction; after Godel, we have lost the initial hopes to establish
this non-contradiction by a formal reasoning, but one can live with a corre-
sponding belief in non-contradiction. The whole structure is certainly very
appealing, but the illusion is that it is eternal, that it will function for ever
according to the same principles. What history of mathematics teaches us is
that the principles of mathematical deduction, and not simply the mathe-
matical theories, have evolved over the centuries. In modern times, theories
like General Topology or Lebesgue’s Integration Theory represent an almost
perfect model of precision, flexibility and harmony, and their applications,
for instance to probability theory, have been very successful.
My thesis is:there is another way of doing mathematics, equally
successful, and the two methods should supplement each other and
not fight.
This other way bears various names: symbolic method, operational calculus,
operator theory... Euler was the first to use such methods in his extensive study
of infinite series, convergent as well as divergent. The calculus of
differences was developed by G. Boole around 1860 in a symbolic way, then
Heaviside created his own symbolic calculus to deal with systems of differen-
tial equations in electric circuitry. But the modern master was R. Feynman
who used his diagrams, his disentangling of operators, his path integrals... The
method consists in stretching the formulas to their extreme consequences,
resorting to some internal feeling of coherence and harmony. There
are obvious pitfalls in such methods, and only experience can tell you that
for the Dirac δ-function an expression like xδ(x) or δ′(x) is lawful, but not
δ(x)/x or δ(x)2. Very often, these so-called symbolic methods have been
substantiated by later rigorous developments, for instance Schwartz distribution
theory gives a rigorous meaning to δ(x), but physicists used sophisticated formulas
in “momentum space” long before Schwartz codified the Fourier transformation
for distributions. The Feynman “sums over histories” have been immensely
successful in many problems, coming from physics as well from mathematics,
despite the lack of a comprehensive rigorous theory.
To conclude, I would like to offer some remarks about the word “formal”. For the
mathematician, it usually means “according to the standard of formal rigor, of formal
logic”. For the physicists, it is more or less synonymous with “heuristic” as opposed
to “rigorous”. It is very often a source of misunderstanding between these two
groups of scientists.
[...]
[/quote]
The point of view also summarizes much of the one I had been trying to convey in this thread as well, which I also think we (at least silently) were butting heads on. It's not just something I made up as an undergraduate as an "idea about how mathematics should be done" that I should "outgrow", but simply a minority report I've stolen from a venerable member of Bourbaki itself.
(Originally, I came across this essay by reading it referenced in one of Doron Zeilberger's many infamous opinion essays).