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I have no problem believing that Americans find the Fahrenheit system intuitive, but you are failing to see that for metric users, Celsius is 100% intuitive. I know exactly what sort of clothes to wear for each gradation (assuming it's not something insane like -60C in which case I'm staying home anyway), whereas I genuinely cannot do the same calculus with just Fahrenheit, even taking into account the 0-100 concept of Fahrenheit, which is in itself busted in various regions from Canada to Saudi Arabia. I have to constantly remind myself of what Fahrenheit means, because I never grew up with it.

This is a theory of mind issue.

> for metric users, Celsius is 100% intuitive.

For metric users, Celsius is 100% familiar. Intuitive means that there are a bunch of hints that can give you an idea of values that you don't know. The fact that 0° Fahrenheit is about as cold as you can easily stand and 100° Fahrenheit is about as hot as you can easily stand is something that gives you an intuition: if it's as hot as I can stand, it's about 100°, if it's as cold as I can possibly stand, it's about 0°. I can figure out intermediate values through converting my feelings into a percentage.

You can of course do that with Celsius too, but Celsius hasn't been built around a range of human feeling, it's been built around the phase changes of water. You just have to remember the human comfort range in Celsius, do all the same calculations as above, multiply the result by the difference between your low human range and your high human range, then add that to your low human range to get an answer. There's no help, and it might as well be arbitrary.

This is a post-facto rationalization for two reasons.

The first is that the Fahrenheit scale wasn't built around a range of human feeling, but originally around a substance whose temperature is easy to stabilize. Following this, the human temperature was set at 96 (later adapted to 98.6) and the melting point of ice at 32 to have 64 gradations to help with measurements linked to specific hardware. If it was designed around human feeling, then 98.6 and the freezing temperature of brine is hardly helpful.

The second is that if it were intuitive on its own, people who don't use the system regularly would still be able to remember the logic, but that's not what typically happens. Every time I need to think in Fahrenheit (which tends to only be online debates about this very topic), I can't picture anything clearly even with the purported 0 to 100 concept. It is a subjective appraisal of temperature that can't help me convert feelings into anything useful because the limits are still arbitrary. If -17.7C is the lowest a person can possibly stand, then Canadians are gonna be iced out. If 37.7C is the highest a person can possibly stand, Saudis are cooked. The number of regions that hold a range that's appreciably close to that 0 to 100 is quite small.

> The first is that the Fahrenheit scale wasn't built around a range of human feeling

How and why Fahrenheit was developed is completely immaterial: what is material is whether and how its range is of value to its users now.

> Every time I need to think in Fahrenheit (which tends to only be online debates about this very topic), I can't picture anything clearly even with the purported 0 to 100 concept.

Your argument is "because I'm not used to Fahrenheit, it must not offer an advantage to people used to it"? Really? C'mon.

> Your argument is "because I'm not used to Fahrenheit, it must not offer an advantage to people used to it"? Really?

But that's your argument for Fahrenheit...

What on earth is "the typical minimum temperature that can be tolerated by humans" though? There are people who seem fine living in parts of the world where it's regularly -30C (somewhat less than 0F), and many of us that would find anything much less than 0C (32F!) regularly to be pretty much intolerable. Resolution is an issue for measuring fever, so we use a single decimal point (36.8 is normal, 37.1 is elevated etc.). Other than that it just never comes up. Agreed that 100C being the boiling point of water isn't that useful for setting oven temperature etc., but at least you know something that's 100C is going to be as hot to touch as putting your hand under scolding water (and likewise 0C is going to be as cold as ice. You're willing to sacrifice that?). Kelvin is far easier to mentally convert to Celsius than Fahrenheit, and at any rate Celsius is still used extensively by biologists, behavioral scientists etc.

> many of us that would find anything much less than 0C (32F!) regularly to be pretty much intolerable.

Really? Barely long sleeve weather.

For you.

Here we see the difference between subjective and objective plainly expressed.

Celcius is more useful in weather forecasting, because for a lot of people it's important to know whether the water outdoors will be frozen or liquid. Example - it's useful to know if there will be ice on road and it's useful to know if the plants outside will die due to ground freeze at night. Giving the temperature in C answers both questions automatically.

"Typical" maximum and minimum temperature as limits are meaningless, different places have significantly different minimum and maximum temperatures.

The resolution might be better for body temperature (I have my doubts, we measure to decimal point in C), but certainly not for cooking. Nobody needs to know the difference between 200 and 201 F in cooking.

> Both Celsius and Fahrenheit convert to Kelvin with a linear transformation.

C doesn't need multiplication tho.

> 4. Scientists don't use Celsius or Fahrenheit. They use Kelvin. Both Celsius and Fahrenheit convert to Kelvin with a linear transformation.

But the slope of the Celsius<->Kelvin is 1.

You just proved my point by missing it, I'm impressed.

> Fahrenheit has nearly twice the integer resolution of Celsius. This is particularly helpful in describing body temperature.

Yet medical practitioners insist on using Celsius in the most of the world, what fools!

> 0 Fahrenheit is close to the typical minimum temperature, and 100 close to the typical maximum temperature, which can be tolerated by humans. Celsius 0 and 100 aren't even remotely close to this: it's surprisingly awful.

I am very rarely exposed to 0 F, in fact, I actively go out of my way to avoid it by seeking shelter during blizzards while on mountain tops.

You're more likely to encounter 0 F in a continental country, but in my temperate maritime climate country, a populated locale hitting -10 C / 14 F is big news, and only rarely would it get to -4 C / 25 F where I live. In other words, I have very little use case for 0 - 32 F.

So its intuitiveness to you, is opaqueness to me. Because you grew up with Fahrenheit, and I grew up with Celsius.

Scientists do use Celsius and Fahrenheit sometimes, unless your definition of scientist excludes everyone who isn't a chemist or physicist.

TL;DR - you prefer Fahrenheit because you think in it. I prefer Celsius because I think in it.