Principia Mathematica is modern and insightful

159 pointsposted 11 hours ago
by matt_d

68 Comments

WillAdams

9 hours ago

For an accessible introduction before beginning this, consider his _Introduction to Mathematical Philosophy_:

https://en.wikipedia.org/wiki/Introduction_to_Mathematical_P...

and for ease of reading see the various PDF versions at:

https://people.umass.edu/klement/imp/

hasley

4 hours ago

Of you prefer an even more entertaining approach and a very gentle introduction into the topic, I recommend the comic "Logicomix" which tells Russel's journey (though not historically correct all the time for story telling reasons).

https://en.wikipedia.org/wiki/Logicomix

igravious

3 hours ago

Logicomix is novel, and done well, but flawed … it's deficiencies lie in what it leaves out which may come across as an unfair charge but in this case the charge is warranted. There is a more historically correct and less orthodox work waiting in the wings for whosoever should attempt it.

glimshe

10 hours ago

If you can read this book cover-to-cover, you're an absolute hero. Sometimes I wonder if they inserted a big logical error in the middle just to troll people under the assumption nobody would bother to read it.

gumby

10 hours ago

You mean you don’t have a framed, signed, bug-bounty cheque from Alfred North Whitehead on your wall??

More seriously, there is indeed a huge logical error at the heart of the whole enterprise but it was not discovered until much later by Kurt Gödel.

steppi

8 hours ago

This is commonly believed, but Gödel didn't identify a logical error at the heart of the whole enterprise, he proved astonishing theorems revealing limitations of any sufficiently powerful formal system. One can kind of think of the Principia as a science experiment to find the extent to which known mathematics could be proven from foundational axioms that could be thought of as "laws of logic". To make their system work, Russell and Whitehead themselves had to add extralogical axioms, such as their Axiom of Reducibility [0] and the Axiom of Infinity, giving empirical evidence (but not a proof) that "laws of logic" alone were not enough. They were also aware of limitations in their own system, such as the inability to define the cardinal $\aleph_\omega$ [1].

Like the article says, what they did was ahead-of-its-time, and a monumental influence on all subsequent work on formal systems, including Gödel's work, regardless of whether Russell and Whitehead achieved their initial aims.

[0] https://en.wikipedia.org/wiki/Axiom_of_reducibility [1] https://www.gutenberg.org/files/78255/78255-h/78255-h.htm#Pa...

robobro

6 hours ago

That's not how to spell Ludwig Wittgenstein!

steppi

6 hours ago

Wittgenstein didn't find logical flaws in the Principia and deeply admired it. He found flaws in Russell's follow up work on Epistemology, "The Theory of Knowledge."

voxadam

9 hours ago

>there is indeed a huge logical error at the heart of the whole enterprise but it was not discovered until much later by Kurt Gödel.

Which leads us to our next borderline impenetrable book, Gödel, Escher, Bach by Douglas Hofstadter.

m-hodges

9 hours ago

I read GEB cover to cover and haven’t stopped thinking about it for years. Not a brag, a nudge that it’s not impenetrable and more people should read it.

black_knight

3 hours ago

GEB is not a difficult read. It is delightful!

It is a popular science book which catches the vibe of mathematical logic in an excellent way. It is not a textbook, nor a piece of research. It's all vibes, but high-quality vibes. If you are in the right headspace it can be really inspiring!

buildsjets

7 hours ago

I’m working on it every day during lunch break. Good old hardcopy.

eru

6 hours ago

I read it cover to cove back in the day and enjoyed it. But I'm not sure more people should read it today.

If they do and enjoy it, good for them! But many parts haven't aged all that well.

However, I can still very warmly recommend 'The Pleasures of Counting' to this very day.

jstanley

3 hours ago

What hasn't aged well? I don't think any of it is dated to any particular time period.

anthonygd

8 hours ago

I read it on my honeymoon 25 years ago. That book sticks with you.

debo_

6 hours ago

Are you still married?

bryanrasmussen

6 hours ago

finally we shall be able to answer the age old question - does Gödel, Escher, Bach: an Eternal Golden Braid stick with you better than a spouse!

analog31

9 hours ago

GEB was one of the books that inspired me to study math in college. It made math come to life in way that my high school courses didn't.

black_knight

3 hours ago

I showed up to first day at university and an older student talked to me for like two minutes before declaring that I needed to read GEB. I dutifully went ahead and bought it, and I still work in logic today.

scubbo

9 hours ago

I'm surprised to hear that that was your perspective! I felt that it dealt with otherwise-opaque topics in a very approachable way.

annzabelle

7 hours ago

My brother's favorite book in 6th grade was Godel, Escher, Bach.

Why, yes, he works as a compiler engineer.

suslik

7 hours ago

> Gödel, Escher, Bach by Douglas Hofstadter.

I gave that book to my mathematician grandma, and she found it so boring she couldn’t finish it - “All this stuff was known for decades”. True anecdote.

eru

6 hours ago

Well, it's a pop-sci tome, not a research article.

However, it is pretty dated these days.

eru

6 hours ago

Eh, that's just a pop-science tome. Nothing impenetrable about it.

jibal

5 hours ago

Utter nonsense ... there is no known logical error in PM. Gödel proved that Russell and Whitehead's goal was unachievable but that's a totally different matter.

OTOH, Russell found a logical error at the heart of Frege's work, and PM fixed it by introducing the theory of types.

kjellsbells

9 hours ago

I used to wonder how likely it was that the printers made some typesetting errors. Who among us could, say, type a thousand pages of APL symbols without introducing a bug?

WillAdams

9 hours ago

There's a reason mathematics was known as "penalty copy" and was notoriously difficult to typeset and even more difficult to turn a profit on.

For a deep dive into both ends of that, see the history of publication of Knuth's TAoCP where the text was originally published traditionally by setting metal type on a composition machine (to the extent possible), then compositors would add the additional characters and spacing material necessary to compose the equations and so forth so as to lay out a galley (which would then be proofed/corrected) --- a successive edition was then typeset using an early imagesetter, which looked so ghastly that DEK considered giving up, but when informed that the imagesetter was controlled by a computer declared, "I am a computer scientist, I can fix that." and expected to knock out a typesetting system over his next sabbatical....

Roughly a decade later, TeX 1.0 was released.... the current version is 3.141592653 (with new versions adding another decimal place as the version tends towards \pi) --- while we're still waiting on the full publication of Vol. 4, it is widely considered that TeX was worth the delay.

karmakurtisaani

4 hours ago

> the current version is 3.141592653

Another instance of a "clever" joke that becomes annoying very fast.

blipvert

4 hours ago

I suppose that to make it slightly less tedious we could just refer to the version using the number of significant digits: 10

inigyou

9 hours ago

apocryphally a typesetter saw "make x as small as possible" at the end of a math problem to be typeset, and did exactly that

taneq

6 hours ago

“Find x” <— here it is!

keltor

9 hours ago

It was required reading for my Logics class in undergrad. Pretty sure it was also on the optionals (aka required) for my Set Theory class as well.

It's also pretty typically a part of History Of Mathematics and Philosophy of Mathematics courses.

derrida

9 hours ago

No it's not.

No it wasn't.

And you did not read it.

EDIT: source: took logic as undergrad + wrote on the tractatus which required a lot of pre-reqs to understand. 0 chance a course at undergrad level ever assigns principia mathematica. I don't care if you went to yale or oxford or ecole normale ... 0 chance. Most charitable interepretation: some pages of it + was on a bibliography. not required reading.

if feel embarrassed, that is the consequence for lieing. There is such a thing as intellectual honesty.

rramadass

6 hours ago

Well said.

Thanks for calling out these sort of posers and charlatans on HN. We should not tolerate these people if we are to discuss/argue/motivate interesting/hard subjects productively.

I automatically discount anybody on HN (until i have looked at their profile/comment history/any personal bio websites etc.) who claim they have read/studied a) Euclid's Elements b) Newton's Principia c) Maxwell's Treatise on Electricity and Magnetism d) Einstein's 1905 Annus Mirabilis papers. e) Principia Mathematica by Russell/WhiteHead f) Godel's Theorem g) Bourbaki's mathematics books etc. etc. They might have browsed it out of curiosity but that is not the same as reading/studying it.

Actual conceptual mathematics/science is intrinsically hard even ignoring the archaic language/notations.

As a good example; the Nobel-prize winning physicist S.Chandrasekhar wrote Newton's Principia for the Common Reader where he explains a subset of the principia (only dealing with gravitation) using modern notation and language. He himself found it quite hard and thus the "common reader" in the title is somebody who has had a good course in calculus and has the motivation to put forth the effort in understanding it.

eru

6 hours ago

Einstein's 1905 Annus Mirabilis papers seem like they easiest of the bunch to just read through. I just pulled up 'Über die von der molekularkinetischen Theorie der Wärme geforderte Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen', the one about Brownian motion, and read the whole thing. It's only 12 pages and fairly accessible; more prose than equations.

(Of course, if you don't read German, you should get yourself a translation.)

See https://myweb.rz.uni-augsburg.de/~eckern/adp/history/einstei...

I don't think I'm smart enough to casually read and understand original works on General relativity, but the Annus Mirabilis work seems much simpler. The famous E=MC2 paper is only three pages.

See https://myweb.rz.uni-augsburg.de/~eckern/adp/history/einstei...

About Gödel: if you are interested in the theorems, and not necessarily their original presentation, you can get plenty of rigorous modern treatments. It's very common for mathematicians to work out simpler proofs and more appealing presentations of famous results over time.

See https://dn721807.ca.archive.org/0/items/uber-formal-unentsch... if you want to give one of Gödel's work a go. It's only 26 pages. Footnote 48a is especially interesting. Overall the prose is crisp, but the notation is rather archaic to modern eyes.

I agree with your general sentiment, and your heuristic in general.

my-next-account

3 hours ago

I've certainly read and studied material explaining f), but I haven't read the original paper (besides, isn't that in German?). The proofs aren't that hard, as I remember them, maybe they're harder in original form? To be clear: I specialized in logic, formal verification and programming language theory at uni. This was a while ago, and I'm on new parent amounts of sleep, so pls b nice.

nonameiguess

4 hours ago

I don't know the exact curriculum and I'm sure it's changed over the years, but one of my girlfriends from back in the day really did go to a school that had one like this. St. John's College, which has two campuses in Annapolis, MA and Santa Fe, NM. They had no majors and everyone learns by reading the classics directly. They also have to learn classical Latin and Greek and read many in their original languages. I don't know everything they assigned, but I remember at least they actually did learn geometry by reading Euclid and calculus by reading Newton.

Apparently, the history is that the school lost its accreditation and had to shut down during the Great Depression, so to attract investors and reopen, it adopted an extremely unique identity with no watering down of curriculum and commitment to western classics in an attempt to combat the rise of fascism.

seanhunter

3 hours ago

They may have learned mechanics by studying Newton but they can’t have learned calculus. Principia includes geometric series and limits etc but given as geometric arguments so you don’t come out of newton’s principia knowing how to do calculus. If they learned the method of fluxions from Newton (which is equivalent to calculus) then I feel very sorry for them missing out on the far better modern presentation of Leibnitz’s calculus that they would get in studying say Spivak or Stewart or any other modern textbook. For the same reason everyone teaches Taylor series (which are fantastically useful) rather than Newton’s wildly inferior series derivation which he used because Taylor series hadn’t been (re)discovered yet.[1]

Euclid isn’t surprising. School children used to learn plane geometry from Euclid until the 1950s or so. I learned geometry at school using a syllabus from Euclid and we learned the modern form of Euclid’s postulates etc but we didn’t study Euclid itself.

[1] Taylor series were developed in the modern form by James Gregory who was trying to reverse engineer how Newton had come up with his series expansions. I say rediscovered above because they were first written down by Madhava of Sangamagrama who gave Taylor series expansions for the trigonometric functions and natural logarithms/exponential function in the 14th century.

tirutiru

2 hours ago

I heard about St. John's from a twitter thread and find it deeply baffling.

It's as if a group of monks wanted to keep the quadrivium and trivium but their clock stopped at the 16th century. One of their faculty proudly said they study analysis by reading Descartes! Which I thought was a highbrow joke but nope, dead serious.

There's a reason that 'standing on the shoulders of giants' is a thing. Dive into the classics after you have gained the maturity from modern texts.

Take one of the easier problems from Rudin. Prove that a continuous function from the unit interval [0,1] to itself has a fixed point. I wonder how a student immersed in the 'classics' would even begin to tackle this.

nimih

8 hours ago

Honestly, other than the length and tedious presentation, I don't really think the material in the Principia Mathematica is outside the reach of an advanced undergraduate. As a point of reference, MIT's capstone mathematical logic course[1] has a syllabus that requires at least as much mathematical maturity, and it wouldn't really surprise me that much to see it as an ancillary or excerpted text.

That said, even if the OP was assigned the text at some point as an undergraduate, I remain a bit doubtful it was actually read.

[1] https://cfreer.org/18.515/

TimorousBestie

7 hours ago

> As a point of reference, MIT's capstone mathematical logic course[1] has a syllabus that requires at least as much mathematical maturity,

The textbooks they use in that course are written in modern notation and are accessible to a knowledgeable reader; neither can be said of the Principia Mathematica. The archaic syntax is a serious issue.

bulbar

5 hours ago

I did give it a try many years ago, I think as undergrad, but gave up after a few pages, because for me it was nearly impossible to parse the syntax.

mathisfun123

8 hours ago

I'm with you - I hate when people exaggerate their bonafides beyond all belief

derrida

8 hours ago

LLMs giving some people way too much confidence to conceptually shoot from the hip hehe

- “effort to refute bullshit is order of magnitude more than to refute it”.

my-next-account

3 hours ago

Derrida, go back to your grave, you messed up the quote!

mathisfun123

7 hours ago

link the syllabi for the classes

debo_

6 hours ago

What if they link the axioms for the classes and leave it as an exercise to the reader to derive the syllabi?

nitsuaeekcm

5 hours ago

For those who aren't familiar with the great but tragic story of Principia and Russell's quest for the foundation of math (spoiler: there is none), there's a really great graphic novel called Logicomix https://en.wikipedia.org/wiki/Logicomix I haven't read it in probably ten years, but it's one of those books and stories I spend an inordinate amount of time thinking about, for whatever reason.

emil-lp

4 hours ago

The foundation of math is (mostly) ZFC.

igravious

3 hours ago

It is not. The foundation of math is contested -- but afaik it is widely held that HoTT is the, erm, hottest contender to the throne https://en.wikipedia.org/wiki/Homotopy_type_theory

qbit42

3 hours ago

There is not a single foundation - you can choose. The differences are rarely important for working mathematicians though. Most know enough of ZFC to get by and ignore foundations tbh

TimorousBestie

7 hours ago

Instead of spending time beating one’s head against Russell and Whitehead, I would advise reading Homotopy Type Theory (aka the HoTT Book). Dependent types are cool and mind-expanding, but higher inductive types are downright mind-altering.

The Little Schemer/Typer could be used as a preparatory text to gear one up for HoTT.

It also has the advantage of being a bit more applicable to functional programming languages, maybe even more so than Mac Lane’s Categories for the Working Mathematician (which I sometimes see suggested to mathematically-inclined Haskell novices).

js8

5 hours ago

I tried to read HoTT. First chapter on type theory is great and pretty easy to follow. The second chapter, I got completely lost. I don't remember why, maybe they fixed it since.

But I find univalence axiom intriguing. I am interested in different approach to types, using triage calculus, which is more "materialist" than "structuralist" - type is given by the structure of the (quoted) term in normal form (unlike lambda calculus, triage calculus makes quoting easy). And I feel like univalence is related to quoting, something like if the two quoted terms are equal under "standard self-interpreter", then they are equal.

leonidasrup

4 hours ago

I would highly recommend "PROGRAM = PROOF" by Samuel Mimram.

It covers everything from pure lambda calculus through dependent type theory up to homotopy type theory. In comparison to the HoTT book, the book "PROGRAM = PROOF" is oriented less towards mathematicians more towards programmers. It contains also a short introduction to OCaml and Agda.

The book can downloaded from the authors web page:

https://www.lix.polytechnique.fr/Labo/Samuel.Mimram/teaching...

https://www.lix.polytechnique.fr/Labo/Samuel.Mimram/publicat...

voidhorse

9 hours ago

I have a copy and like it much. However, i was always partial to Frege's Begriffschrift. His notation was really creative. It's a shame Russel's deflation of that project has sentenced it to the rubbish heap of history.

igravious

3 hours ago

The Begriffschrift has in no way been consigned to the rubbish heap of history. What gave you that impression? It is seminal. That it had one unresolved paradox in its set-theoretic foundations does not scupper the philosophical insights, nor the creative notation, nor the more-or-less novel approach of conjoining mathematical functions and logic to give us predicate logic (apologies for this brutally simplified sketch)

i like to think of Frege and the Begriffschrift like this

Boole: logic + algebra = algebraic logic

Frege: logic + functions = predicate logic

ergo, if Boole is rightly deified then so should Frege regardless of minor infelicities (which prompted type theory anyhow) -- again, apologies if this is totally misleading

makerdiety

6 hours ago

So... the ancient childish attempt to prove mathematics using mathematics (Gödel's Incompleteness slew the challenger) can be used to help me be a better TypeScript programmer? I learned something new today.

bulbar

5 hours ago

Why the belittling language? You actually can prove the completeness and consistency of portions of mathematics.

While axioms were known in ancient times, only Hilbert started the whole "prove Mathematics" thing.

How else would you prove mathematics and why would that be childish to use math? The limitations discovered were quite surprising back then.

data_maan

5 hours ago

It always amazes me how a random dump of someone who read the first 40 pages of PM attracts dozens comments on HN.

This really must be a very math-starved community of people who wanted to learn math but never quite could.

laichzeit0

5 hours ago

Two thoughts on someone who went out of their way to learn math:

1. If you can already program, the worst thing you can do is think of mathematics as learning a programming language. It is not, and you will waste your time being frustrated with things like syntax and notation. You get “used to” mathematics by doing it, and it’s something on its own. Just go with it. It’s ok to be confused.

2. Do the exercises, and stop asking for “solution manuals”, the point is to get you thinking and the struggle is most important part, not whether you got it “right”. Again, I think this is a programmer centric way of looking at things: “how do I know it’s right if I can’t compile it”.

Maybe that’s why programmers like the foundations of mathematics. Like if somehow they could just go to the bottom of things, the assembler/machine code of sorts, the whole enterprise would make sense. Counterintuitively, the really great mathematicians of yore, did mathematics before it was anywhere close to formalized.

futune

35 minutes ago

I think your latter comment is kind of analogous to people writing python (or any high-level language) without understanding assembly. I think maybe that reduces the mystery a bit?