The reason I started the discussion is because I think examples like "fruit" where the common usage of the word deviates from any strict definition can help us to understand language and language acquisition better.

I suggest reading up on Eleanor Rosch's prototype theory, it explains the whole categorisation thing very clearly. The basic theory is that our categories aren't Aristotelian classes, but are fuzzy, and formed from seeing exemplars of a class and extracting the most common features. It's a well-understood property of cognition and has plenty of experimental backing.

In the case of cucumbers, I'd say it fails the 'fruit' test because it lacks almost all the features I associate with fruit: it's not red/yellow, it's not sweet, I don't eat it for a snack or dessert, and it doesn't have obvious seeds or pits inside. Therefore I would look at you very oddly if you told me that it was.

Was your point, then, that you should use words in the way which is most likely to be clear and useful? If so, I agree, and would rather address it directly.

The clear and useful definition varies, of course, with context--a plant biologist and a pastry chef use the word "fruit" differently, and that's okay! The trouble arises when you have two people in conversation trying to use a word for which they have different contexts, as is the case when lay people interpret "theory" as "guess," since that's what it often means in prose. In such cases, more or different words are needed to ensure the right meaning is being interpreted.

One way in which I've observed some very smart and numerate people falling for this fallacy is when they run out of cash in bars and are forced to take money out of those rip-off ATMs that charge $3 or so per transaction. People will often take a larger amount of money than necessary, rationalizing that the rip-off isn't that bad if it's only a small percentage of the amount (I've heard this "reasoning" expressed loudly several times). This despite the fact that tomorrow they'll walk by their own bank's ATM from which they can take money without any fees, so there's absolutely no benefit from taking more money than necessary from the expensive one.

I am myself not immune to this feeling, even though I'm perfectly aware it's completely irrational. I would feel awful if I paid $3 to take out a twenty and then took $100 without a fee next day, but paying $3 to take $120 feels much less bad.

it's not clear why we should privilege one's experience other the other

Because in the argument as described, Lemon does have more than his experience to go on--he also has the agricultural definition. That's why we invented definitions. To resolve these arguments.

In the same way, wheat is both a grain and a vegetable.

Isn't this another clear example of prioritizing the technical definition (and, in fact, an arbitrary one of several overlapping technical definitions) over the common usage, which you appeared to be arguing against? If you tell someone you're cooking vegetables, and they come over to find you with a bowl of cream of wheat, you've been misleading, and I don't see how that's a productive use of language.

As a rule of thumb, I prioritize the precise definition unless it's misleading in the given context. When I say "the performance was so bad, they threw rotten fruit," no one will be confused if some of the projectiles were tomatoes. But I wouldn't say "I'm serving fruit and cheese" when I plan to put out tomato slices with mozzarella. It's true, but it creates a false expectation.

There was an article in Scientific American a few years ago about the Traveler's Dilemma and how human beings make more money than the Nash Equilibrium tells them to. Edit: Wikipedia summary

It occurred to me that the percentage fallacy might explain why people give high numbers in this version -- the Nash equilibrium is pocket change compared to the max payoff. The same is true for the reward for undercutting; you might not be so motivated to low-ball if your reward for doing so is 2% of the max payoff.

It would be interesting to see an experiment where the payoff for giving the low estimate varied. If you were playing the game with a $10 bonus for lowballing, would you give the Nash equilibrium of $10? Or would you maybe go for the $40s or $50s hoping the other person would go even higher? My guess would be that as the reward for undercutting as a percentage of the max reward increases people get more and more vicious, and at some percentage people will default to the Nash equilibrium.

Hi LW,

My name's Dan LaVine. I forget exactly how I got linked here, but I haven't been able to stop following internal links since.

I'm not an expert in anything, but I have a relatively broad/shallow education across mathematics and the sciences and a keen interest in philosophical problems (not quite as much interest in traditional approaches to the problems). My tentative explorations of these problems are broadly commensurate with a lot of the material I've read on this site so far. Maybe that means I'm exposing myself to confirmation bias, but so far I haven't found anywhere else where these ideas or the objections to them are developed to the degree they are here.

My aim in considering philosophical problems is to try to understand the relationship between my phenomenal experience and whatever causes it may have. Of course, it's possible that my phenomenal experience is uncaused, but I'm going to try to exhaust alternative hypotheses before resigning myself to an entirely senseless universe. Which is how I wind up as a rationalist -- I can certainly consider such possibilities as the impossibility of knowledge, that I might be a Boltzmann brain, that I live in the Matrix, etc., but I can't see any way to prove or provide evidence of these things, and if I take the truth of any of them as foundational to my thinking, it's hard to see what I could build on top of them.

Looking forward to reading a whole lot more here. Hopefully, I'll be able to contribute at least a little bit to the discussion as well.