I lived in the United States for six years, during which time I refused to learn Fahrenheit. I was forced to give in to using inches because, unlike every tape measure I owned in Canada that had both inches and centimetres, every measuring tape I could find at my local hardware store was inches only. For this and other reasons, it wasn’t practical to resist.
But I prided myself in my ignorance of Fahrenheit. It’s odd to be proud of ignorance, but using Celsius exclusively helped me hang on to my Canadian identity while living in a foreign country. Sometimes, people would ask me what the forecast was, and you just know that I made it a whole thing.
But when the pandemic hit, I started calling home to my family a lot more often. My grandparents – snowbirds who lived in Florida half the year – didn’t know Celsius. That made conversations difficult (“how is the weather?”) and I wasn’t going to let a my pride get in the way of connecting to my family. So after years, I eventually did learn Fahrenheit. And then I promptly moved home to Canada.
This is all to say, I have some complicated feelings about Fahrenheit.
Because the thing is, during my six years in the United States, I kept hearing the same thing from Americans. Smart people – coworkers, friends! – would all tell me something along the lines of:
Yeah, sure, the Metric System is better for everything… except ambient air temperature! That is the one thing that Fahrenheit is better for. You guys just don’t get it.
This. In. Furiated me.
And so, when I heard Casey on the latest ATP episode say something to this effect, I paused the recording to write this post. (Sending feedback before finishing the episode is poor form, I know.) I was compelled to write this because I think he and I get our dander up about this topic in the same way, from opposite sides. And I actually think I have a way for us to square the circle on this. And this has been bothering me for years.
I want to see eye-to-eye with my American friends, and podcast hosts. So this blog post is an olive branch of sorts.
The Case For Fahrenheit
I’m going to do the thing that Metric System advocates never do: I’m going to admit that is neat that Fahrenheit stretches from zero to a hundred, as a range from “really cold” to “really hot.” It is! A hundred is a nice round number. It’s very neat. I don’t think a reasonable person could deny this, even though I did for years, which maybe reflects on me a bit. I’m sorry.
It is also convenient that the Fahrenheit degrees are small enough that thermostats can be adjusted by whole degrees. I don’t mind that my car adjusts air temperature in half-degrees Celsius, but I must admit that it would look cleaner if they were whole numbers. And I once owned a space heater that adjusted its digital thermostat by whole degrees Celsius. I wanted more control so I switched it to Fahrenheit. I enjoy the finesse that comes with smaller degrees, and I appreciate the simplicity of design that follows from that.
There is no “but” coming. There is no other shoe that’s about to drop, or backhanded compliment. The Europeans and the Australians and the other Canadians… they won’t admit that you’re right about the ambient air temperature thing. I will.
I hope that you’re curious about why no one else will admit that you’re right about this, because I think it’s fascinating. There are two nuanced points in this debate that get lost in conversion translation.
Acknowledging the Arbitrary
When I hear Americans describe how intuitive the Fahrenheit system is, I feel like I’m going nuts. “This is so intuitive”, they say, “because it goes from zero to a hundred.” Or maybe they’ll say “the sixties feel this way and the seventies feel that way, and it all makes sense!” Yeah! Of course it makes sense to you. You grew up with this system! But going from zero to a hundred did not help it make sense to me.
Any system used to measure something like air temperature, or any temperature, is going to be arbitrary. It’s going to have tradeoffs about how it works, what it’s optimized for. And although it is neat that Fahrenheit goes from zero to a hundred, that is arbitrary. Consider a temperature scale like Fahrenheit but that goes to 120 instead; we’d be able to reason about temperature like an analogue clock. Or, it could go to 60 like the Babylonians intended, so we could do fun fractions. Neither of these would inherently be more intuitive.
What is intuitive is the system you know.
And even though it is neat that Fahrenheit goes from zero to a hundred, that isn’t how people reason about temperature. For example. If it’s 35ºF outside, and you go inside where it’s 70ºF, do you think about that as being “twice as warm”? Probably not. Zero to a hundred suggests percentages, so do you think about inside being “35% warmer” than outside either?
Maybe I’m wrong here, but I think people feel temperature differences in absolute terms in degrees, not in terms of multipliers or percentages.
Going from zero to a hundred is neat. I like how it makes degrees act like a percentage, truly. But I don’t think that going from zero to a hundred helps people reason about temperature in a way that Celsius does not. I have the same intuitive understanding for Celsius that you have for Fahrenheit. I don’t think either is inherently better. The one that feels like it “makes sense” is the system you know – please believe me on this.
Yeah? Are we still friends? Okay I’m glad.
Putting the “System” in “Metric System”
I mentioned tradeoffs earlier: there are benefits and drawbacks to any temperature scale. I don’t think many Americans understand the value in Celsius because I don’t think many of them actually know the Metric System. The systemic nature of Celsius makes up for the annoyingly large degrees, among its other drawbacks, in my opinion.
When I took high school physics, it was revelatory. Suddenly, many different things about the world were interconnected. They always had been. I loved it. Learning about how the speed of sound is affected by air temperature, and the Doppler effect, and total internal refraction… It was so fun to learn how the real world could be modelled. And one part of this awakening was the realization that all these units were connected, just like the world was.
The Metric System is arbitrary, like Customary Units and like every other measuring scale. But by making very intentional decisions, the Metric System connects together the different aspects of our physical reality into one elegant, beautiful system. Let me explain.
Using one cubic centimetre of water as a baseline, we have the definition for one gram of mass and for one millilitre of volume. Distance, mass, and volume are connected, boom. Next: raising that water’s temperature by one degree Celsius would require one calorie of energy. We could continue, to describe the connection to Joules, and Watts, and so on… but my point is that these are all connected by the definition of the units themselves. And that is also pretty neat.
By learning a system of measurements that makes it easy to reason within, I think people are able to more easily develop an intuition about that reality. Celsius fits within that system, even if it has tradeoffs.
My American friends: most of you don’t know the Metric System and so most of you can’t appreciate the value that the system affords. And I know that the idea of change is hard – it sucks for my family members who grew up before Metrification in Canada. And I appreciate the fact that most people don’t need to intuitively relate mass and energy, or whatever. But I relish in it. I love being able to reason about the size of my espresso machine boiler and its power draw and volume, and kilowatt hours, and all that. I just think it’s neat.
This doesn’t make Celsius a better system than Fahrenheit – it’s just different tradeoffs.
While (I think) I do understand the value in going from zero to a hundred, I don’t think Americans understand the value of the Metric System. This isn’t a flaw or a shortcoming, in any way. It’s just something that I don’t think you all are aware of. An “unknown unknown.” And if you care about measuring ambient air temperature as much as I do, I thought you might be interested to learn.
The tl;dr here is:
- Fahrenheit is convenient for ambient air temperature, but going from zero to one hundred didn’t make it easier for me to learn.
- Celsius becomes more valuable when it’s used within the entire Metric System, leading most Americans to be unaware of that value. This is why no one will admit that you’re right about the first point.
I still prefer the tradeoffs that Celsius makes over the ones Fahrenheit does. But I see you. We can agree to disagree.
Time to go listen to the rest of that podcast episode.