Does philosophical position (platonist, formalist, etc) play a role in thinking about mathematics, and the subsequent research? That is, for example, did "platonist" position, or "formalist" position affect how Godel, Turing, Hilbert or Cohen thought, and carried out their research?

If yes, how? Does it "shape" their point of view -perhaps enabling them to look at things differently?

If not, why not -why mathematical research may be immune to philosophical position?

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    I would say: NO. "The independence of the continuum hypothesis (CH) from Zermelo–Fraenkel set theory (ZF) follows from combined work of Kurt Gödel [a "platonist"] and Paul Cohen [a "formalist"]." Apr 1, 2022 at 12:34
  • Hilbert and his followers were certainly motivated by their formalist philosophy. Godel was probably motivated by his realist philosophy. Frege, Russel and other logicists were motivated by epistemology. Constructivist math is motivated by intuitionism. Some branches of math like transfinite math or foundations of analysis were implicitly motivated by realism. Apr 1, 2022 at 16:31
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    @DavidGudeman - but your examples are all of logicians involved into "foundational researches"... Mainstream mathematics is quite independent from metaphysical theories. Apr 1, 2022 at 16:50
  • @MauroALLEGRANZA I'm interested in foundational research only!
    – Ajax
    Apr 1, 2022 at 17:02
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    Isn't it a more interesting and deeper philosophical question that "why you're only interested in foundational research only"? A fit answer for your title question may be lied in the insight from it... Apr 2, 2022 at 2:26

2 Answers 2


Just personal intuition: In the case of foundational research it seems that research field and philosophical position are often correlated. For example Joel-David Hamkins' and Hugh Woodin's work seem to be roughly correlated with their respective philosophical positions. Similarly structuralism is a popular position amongst those who are more category-theoretically inclined, and those who are of a finitistic persuasion often find their way into recursion theory.

To really substantiate this though, we'd need some serious examination of empirical data and I don't know of any such work. However, Colin Rittberg does have a nice paper linking metaphysical view with practice:



Shapiro in Thinking About Math talks about this. For a brief period it probably was the case that philosophy determined who studied what. And in some sense it is probably still around today. But the effect was probably highest in the past. Poincare rejected any actual infinite, whereas Godel said just because we can’t construct it doesn’t mean it doesn’t exist platonically.

Here’s a quote of Godel found in Shapiro’s Thinking About Math, “If, however, it is a question of objects that exist independently of our constructions, there is nothing in the least absurd in the existence of totalities containing members.” Pg. 10

If there really are mathematical objects independent of us, we can use things like impredicative definitions. Poincare rejected any actual infinity, independent of us or otherwise. Therefore he abstained from certain definitions Godel had no problems with. Things like defining objects by using a collection that already contains it. Without actual infinities in some sense, these definitions are “viciously circular” to Poincare.

And for similar reasons, intuitionist mathematics has to reject things like the law of excluded middle.

BUT, Shapiro is quick to show, these are isolated moments in the history of mathematics. The dominance of accepting things like the law of excluded middle, impredicativeness, axiom of extensionality, have proven too useful and successful for natural science and studying further mathematics.

These temporary disagreements of a philosophy-first mathematic rapidly gave way to objects and definitions mathematicians “could not help using…and with hindsight we see how impoverished mathematicians would be without them”. “These nuisances proved to be artificial and unproductive”.

So now there is a complete retreat of philosophy-first mathematics and more of a sense of following what is successful.

That isn’t to say everyone works on the exact same stuff and no one has any disagreements. Joel David Hamkins does say mathematician’s “beliefs” about realism, multiverse, which extensions of set theory, etc do affect what they study to some degree.

But the language of mathematics can still be used and understood regardless of philosophy. That is kind of a miracle of language in a way.

  • Thanks for answering. I'm quite new to this. What does this even mean - "Poincare rejected any actual infinity, independent of us or otherwise."? More naively, what's there to reject about actual infinity (as a concept)?
    – Ajax
    Apr 9, 2022 at 17:36
  • It’s a question of where does one go looking for foundations of mathematics. Poincare thought actual infinities never exist, only potential infinities. So basing a foundation upon something which may not exist is already shaky for him I’d imagine. He probably had physical reasons for doubting actual infinity, but also he rejected “impredicative” definitions for leading to circular reasoning and paradoxes. Impredicative definitions feature in our most foundational math, ZFC set theory. But no one has paradox free mathematics which is able to help explain so much of the natural world.
    – J Kusin
    Apr 9, 2022 at 18:43
  • But now we don’t need to spend as much time worrying about infinity like Poincare goes the story. ZFC and similar are so successful, we use their histories of success, which didn’t exist to Poincare as foundations.
    – J Kusin
    Apr 9, 2022 at 18:46

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