[dalke]

But Chomsky didn't change when he was old. He became well-known for his politics when he was in his 30s. Dawkins was 35 when his "The Selfish Gene" was published, and 45 when "The Blind Watchmaker" was published. Both are involved in areas that interested them when they were under 40 years old.

My point is that neither Chomsky (and now neither Dawkins) fits your description ... unless you say that people 30-40 of age are already old?

My other point is that most successful scientists don't shift into topics drastically outside their interests when they were young. Dirac? No. Erdős? No. Barbara McClintock? No. Von Braun? No. Karl Sharpless? No. Jocelyn Bell Burnell? No. Just take the list of Nobel prize winners for science and see how few of them got into politics later in life, or for that matter moved into topics markedly outside of their original area.

Yes, of course some do. But car dealership owners, and chefs (Samak Sundaravej, PM of Thailand, was a television chef for 7 years), and priests and singers also get into politics. So my last point was that there's nothing of note about a few scientists getting into politics as they get older, because people of all sorts of different fields go into politics as they get older.

Hence, my comment that there are strong biases which affect your parenthetical observation.

[sashahart]

And Dawkins was probably an atheist when he was young too. So what?

I have never made a generalized claim about all scientists so you are beating a straw man. I have mentioned a certain pattern which you will see recurring if you have any significant awareness of the famous scientists in a particular field... that pattern is not "getting into politics" but rather "moving well beyond the scientific area where they made their name"

[dalke]

And I'm saying that that pattern doesn't exist, at least no more for scientists than for any other field. (If you broaden your field to other than politics, then think about all the other people who have switched careers. President Obama was a law professor earlier in life. Sting was a schoolteacher.)

I gave a list of famous scientists who did not move well beyond the scientific area where they made their name. I'll add more: Cyrus Levinthal, Dorothy Hodgkin, Hermann Weyl, Edsger Dijkstra, Maria Mitchell, Abraham Maslow, John Wheeler. The list goes on and on. Again, consult a list of Nobel Prize winners and see how it's no more common for "famous scientists in a particular field" to do what you say they do than for any other profession.

I posit that you have sampling error, in that you've mostly only heard of scientists who are known in their field and are also known for work outside their field.