> more or less invented types to solve a problem he was having with set theory.

For people who haven't encountered it yet, this problem is the famous "Russell's Paradox"[1], which can be stated as

Consider the set R, consisting of all sets S such that S is not an element of S.

Ie in set builder notation

R = {S : S ∉ S}

and then the paradox comes from the followup question. Is R an element of R? Because of course if it is in R, then it is an element of itself so it should not be. And if it's not in R, then it is not an element of itself, so it should be. This is a logical paradox along the same lines as the famous "The barber in this town shaves all men who do not shave themselves. Does he shave himself?"

In modern axiomatic set theory, Russell's paradox is avoided these days by the "axiom of regularity"[2] which prevents a set builder like "the set of all sets who are not members of themselves", so what I wrote above would not be accepted as a valid set builder for this reason by most people.

Russell proposed instead Type theory which got revived when computer science got going.

[1] https://en.wikipedia.org/wiki/Russell%27s_paradox

[2] https://en.wikipedia.org/wiki/Axiom_of_regularity

> The barber in this town shaves all men who do not shave themselves. Does he shave himself?

I'm not familiar with this one but is it misstated here? The barber doesn't only shave men who don't shave themselves. If he doesn't shave himself then he shaves himself and therefore can shave himself without contradiction. If he shaves himself he can shave himself without contradiction. Either way he shaves himself.

(Or maybe I'm just bad at logic)

Yes you're right it's typically stated as "shaves all those, and those only, who do not..." https://en.wikipedia.org/wiki/Barber_paradox

I prefer the version that leaves the barber's gender unknown (i.e. could be a woman):

> The barb in this town shaves all men who do not shave themselves. Does the barber shave themself?

Bertrand Russel also was - and hopefully still is - a public intellectual, like Einstein or Chomsky (for better or worse), whose opinions on many areas of life reached ordinary people. His values were ahead of his time.

This is a wonderful interview with him that gives a great sense of what he was all about:

• A Conversation with Bertrand Russell (1952) https://youtu.be/xL_sMXfzzyA

Russell also lived a long time, with family who did too.

While young his grandfather told Bertrand about meeting Napoleon. Late in life Bertrand watched the moon landing on TV.

Obviously that two experiences that span more than one life time, but they are very far apart.

https://www.openculture.com/2022/05/philosopher-bertrand-rus...

His (ex-)wife Dora was my wife's neighbour, she was quite a force in her own right (and lived to 92):

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

I understand that Professor Yaffle -- the woodpecker bookend in the classic kids' TV show Bagpuss -- was loosely based on Russell.

There's a live action Bagpuss film due: https://www.bbc.co.uk/news/articles/crrjwlvxknko

They had a long history of correspondence. The preceding letter is archived and you can probably get a copy. (https://bracers.mcmaster.ca/79128)

> Jan 6/1962 Re nuclear disarmament and world government. BR is not inclined to agree or disagree with Mosley's views, but he does think that Mosley is "rather optimistic" in his expectations. BR provides criticism of his main two objections. (A polite letter.)

> Jan 11/1962 Mosley wants to lunch privately with BR about their differences.

These are basically all the letters exchanged with Mosley:

https://bracers.mcmaster.ca/bracers-basic-search?search_api_...

This letter makes perfect sense to me if he had sent it as his first reply to a fascist in 1946. Why did he correspond with him over 43 previous letters from 1946 and only in 1962 act as though he had principled objections to corresponding with fascists? The tone is not "this time you've gone too far", or "I have decided we're not getting anywhere", but "We have nothing in common and could never converse". I wonder if he realized it was the same guy, or was submitting this to some public forum.

As I wrote above they did not have a long history of correspondence (previous correspondence was mainly with a Gordon Mosley).

The letter written by Russell was preceded by a letter from Mosley (maybe trying to bait BR) on "the root differences between us" in December 1961 to which BR replied with two letters before Mosley tried to invite BR for a private lunch which prompted the letter of note response. I think this makes perfect sense, he initially engaged intellectually, but when invited to associate privately he strongly refuses.

The long correspondence that you describe (from the 40's to the 60's) was with Gordon Mosley of the BBC, and not with Oswald.

The only letters that Russell personally wrote to Oswald were sent in January 1961.

I was incorrect here. The letters were all from december 61 to jan 62.

That's incorrect if you read the summaries and recipients, most of the Mosleys are not Oswald Mosley.

You are absolutely right! The couple from 62 are correct.

For general context, this was addressed to post-ww2 Mosley, in the 60s, who argued a unique form of holocaust denialism at the time. He didn’t take the position that the holocaust didn’t happen, he took the position that it was justified.

Mr Mosley also had a pretty well known son lol.

For reference, this is alluding to Max Mosley who used to be prominent in formula one car racing https://en.wikipedia.org/wiki/Max_Mosley

As well as F1, he was quite a popular figure in some Nazi cosplaying dungeons.

Thats what I was really trying to get at.

Actually he successfully sued the tabloids for defamation on the grounds that while, yes he had a cosplaying dungeon, and yes the “attendees” were all in uniform, none of them were in Nazi uniform. To twist the knife he then went on to bankroll all the phone hacking civil cases against the same tabloids.