• I think they can only mean either "variance" or "badness of worst case"

In the context of financial markets, risk = variance from the mean (often measured using the standard deviation). My finance professor emphasized that although in everyday speech "risk" refers only to bad things, in finance we talk of both downside and upside risk.

Gettier walks into a bar and is immediately greeted with the assertion that all barroom furniture is soft, unless it's a table. So he produces a counterexample.

I think atypically, just like everyone else.

When I was in law school, I devised my own idiosyncratic solution to the problem of studying a topic I knew nothing about. I'd wander into the library stacks, head to the relevant section, and pluck a book at random. I'd flip to the footnotes, and write down the books that seemed to occur most often. Then I'd pull them off the shelves, read their footnotes, and look at those books. It usually took only 2 or 3 rounds of this exercise before I had a pretty fair idea of who were the leading authorities in the field. After reading 3 or 4 of those books, I usually had at least enough orientation in the subject to understand what the main questions at issue were - and to seek my own answers, always provisional, always subject to new understanding, always requiring new reading and new thinking.

--David Frum

The oldest (non-dead) source I could find was this 2008 post by someone else quoting Frum.

Related to: Update Yourself Incrementally and For progress to be by accumulaton and not by random walk, read great books

From the article:

the failure to look rightward and see rational people.

This effect was reproduced in studies by Jonathan Haidt. Liberals don't mimic conservative ideology as well as conservatives can mimic liberal arguments. They just can't see the reasons, and tend to attribute differences to malice.

Feynman knew physics but he didn't know ornithology. When you name a bird, you've actually identified a whole lot of important things about it. It doesn't matter whether we call a Passer domesticus a House Sparrow or an English Sparrow, but it is really useful to be able to know that the male and females are the same species, even though they look and sound quite different; and that these are not all the same thing as a Song Sparrow or a Savannah Sparrow. It is useful to know that Fox Sparrows are all Fox Sparrows, even though they may look extremely different depending on where you find them.

Assigning consistent names to the right groups of things is colossally important to biology and physics. Not being able to name birds for an ornithologist would be like a physicist not being able to say whether an electron and a positron are the same thing or not. Again it doesn't matter which kind of particle we call electron and which we call positron (arguably Ben Franklin screwed up the names there by guessing wrong about the direction of current flow) but it matters a lot that we always call electrons electrons and positrons positrons. Similarly it's important for a chemist to know that Helium 3 and Helium 4 are both Helium and not two different things (at least as far as chemistry and not nuclear physics is concerned).

Names are useful placeholders for important classifications and distinctions.

If your loss function is severely skewed, you do NOT want to be unbiased.

The most important decisions are before starting a war, and there the mistakes have very different costs. Overestimating your enemy results in peace (or cold war) which basically means that you just lose out on some opportunistic conquests but underestimating your enemy results in a bloody, unexpectedly long war that can disrupt you for a decade or more - there are many nice examples of that in 20th century history.