For me to argue further would be to argue the meaning of "failure" in this context, when I'm pretty sure I actually agree with you on all of the substance of our posts.

I really do not want to argue about semantics either, but our agreed interpretation makes Niel's statement equivalent to "our visual system is not optimal for non-ancestral environments", which is highly uninteresting. I think the Dawkin's larengyal nerve example is much more interesting in this sense, since it points out body designs do not come from a sane Creator, at least in some instances (which is enough for his point).

If everyone was to take Landsburg's argument seriously, which would imply that all humans were rational, then everyone would solely donate to the SIAI. If everyone only donated to the SIAI, would something like Wikipedia even exist? I suppose the SIAI would have created Wikipedia if it was necessary. I'm just wondering how much important stuff out there was spawned by irrational contributions and how the world would look like if such contributions would have never been made. I'm also not sure how venture capitalist growth funding differs from the idea to diversify one's contributions to charity.

Note that I do not doubt the correctness of Landsburg's math. I'm just not sure if it would have worked out given human shortcomings (even if everyone was maximally rational). If nobody was to diversify, contributing to what seems to be the most rational option given the current data, then being wrong would be a catastrophe. Even maximally rational humans can fail after all. This wouldn't likely be a problem if everyone contributed to a goal that could be verified rather quickly, but something like the SIAI could eat up the resources of the planet and still turn out to be not even wrong in the end. Since everyone would have concentrated on that one goal (no doubt being the most rational choice at the moment), might such a counterfactual world have been better off diversifying its contributions or would the SIAI have turned into some kind of financial management allocating those contributions and subsequently become itself a venture capitalist?

Speaking from a physical perspective, assuming that "$\Delta x$ is small" is a meaningless statement. Whenever we state that something is large or small, unless it's a nondimensionalised number, there is something against which we are comparing it.

Simple example, which isn't the best example but is fast to construct. Comparing $1 to $(mean GDP from country to country)

*$1 is a small amount of money in the USA. Even homeless people can scrape together a dollar, and it's not even enough to buy a cup of coffee from Starbucks. It's almost worthless.

*$1 is a large amount of money in Nigeria. The GNI is around $930 per capita per year[1], so if you're lucky enough to make the mean income, you'd better not be frittering away that $1; it's vital if you want to pay your rent and buy food.

So we can't say $\Delta x$ is a "small amount of money" without qualification; it seems like when you conclude that, we are actually concluding $\Delta x / X$ is small, the original proposal. A better measure might be $\Delta x / \sqrt{XYZ,3}$, so that the scale in each direction doesn't change (but that's just choosing a different coordinate system, so not that relevant).

Your argument seeks to confirm the original proposal, not refute it, and you've pointed out that sometimes higher derivatives can be important.

(Incidentally, your second example - about nonmixed second derivatives - became clear to me only after some thought. You might want to include a clause like "Because after the first $50, the second derivatives represent a sudden jump down in net utility as we get less bang for our individual buck".)

[1] http://hivinsite.ucsf.edu/global?page=cr09-ni-00&post=19&cid=NI

Hm, interested.

Will having more sex make your relationship happier?

I think it's safe to say that having less sex will make the relationship less happy, so there is some causality involved.

My source was http://www.youtube.com/watch?v=9Cd36WJ79z4 is an autotuned piece which includes footage of Feynman speaking those words, but it looks like it's from interviews with BBC's Horizon.

See under "Doubt and uncertainty":

http://www.bbc.co.uk/sn/tvradio/programmes/horizon/broadband/archive/feynman/index_textonly.shtml

Nice. Do you have a source for that? Google didn't come up with much.

[EDIT: Found to be erroneous! Sorry!]

I don't feel frightened, not knowing things; I think it's much more interesting.

-Richard P. Feynman

Unfortunately, practical experience of what people mean when they advocate less politeness in the cause of more communication says otherwise.

That is a rather offensive piece of pattern completion you just did there. If you want to characterize what you have seen on this thread as "repeated special pleading for bad communication skills" then you may be putting your finger on something important. But when you try to conflate that with the incidents reported in your link, then you are engaging in a particularly inappropriate form of stereotyping. Where, on this thread, have you seen overt hostility to women? Or any other form of nastiness?

As with any other male-dominated community, we exhibit traces of sexism. But I see no evidence that rationalizations against politeness here are some kind of cryptic anti-woman signaling. Some of us, of both sexes, really do prefer to receive our negative feedback undiluted.

I think that threats often do work. I have a landlord, who uses a letting agent that we pay for our utilities. The letting agent stinks, and our electricity bill just trebled from the spring quarter into the summer quarter. Summer is warmer and brighter than spring - I would expect my bill to decrease by at least 5%.

So far, so bad, except that I was away for six weeks of that quarter, and most of my housemates were travelling for at least 2 weeks - my bill should have halved on top of this 5% decrease. There's a disparity of an expected 47.5% of my previous bill with the observed 300% actual bill (or, being more conservative and taking us all as having been travelling for 2 weeks each, 80% of my previous bill). This isn't credible, and I'm not going to pay it.

My landlord likes the letting agent (presumably they're cheap). I expect shortly to be threatened with late-payment charges or even eviction. This expectation of a threat has already made two of my housemates pay the obviously unfair bill, despite us all being agreed that we do not owe the amount demanded.

I recently changed mobile telephone provider, despite being on contract with my previous provider ([blanked]) for another three months. I was told I must pay the balance of the contract, and told them to go whistle for it. Apparently their SOP is to just tank the customer's credit rating.

If I had been told this, the [blanked] would have easily been less valuable to me than my good credit rating. I wasn't told by $_PROVIDER, who now will not respond to my contacting them, but intend to pursue them to ensure that they don't do this. If they had threatened me, I would definitely have paid.

Threats seem effective.

EDIT: Deleted some personal information.