Leah asks:
What’s something in (insert comment authors field here) that seems basic or important to you but others outside your field don’t know?
Marginal tax rates is a big one. A lot of people think that if you make more money, all of a sudden all of your previous money is taxed at a higher rate and you could actually lose money. That’s not true. Only your new money above the tax bracket gets taxed more. The money you earn below that bracket gets taxed at the exact same amount. The only way you would lose money is if you had a tax rate higher than 100%, which we don’t.
How insurance works is another. That’s a bit more complicated, but it’s also magical. See the linked post if you want to learn more.
Then there’s just standard stuff like sunk costs.
Grumpy Nation, what’s basic in your field that people outside don’t know?
Grumpy Rumblings (of the formerly untenured) 
August 26, 2022 at 4:39 am
I work in polymers. Most people think all plastic is cheap junk when in fact there are really amazing products out there that do all kinds of cool stuff. Many consumer product companies like dishwasher manufacturers use the cheapest stuff possible that will function through the warranty period. They could have spent Pennies more for a higher quality material and got parts that last much longer but choose not to. That’s why great grandmas fridge is 75 years old and still runs. It may suck a lot of energy but it still works. Before computer modeling, you had to build in huge fudge factors on products to make sure they lasted.
Part of what’s kept inflation in goods low for all this time is this kind of productivity (using cheaper materials, thinner walls, automation, etc), but I hate the design for obsolescence part of manufacturing goods.
I will fully admit that the plastics industry has a ways to go when it comes to recyclability but what most people don’t know is it’s role to help the environment. When you make cars and planes lighter, they use a lot less fuel. For planes especially, the numbers are staggering. Similarly, plastic goods are cheaper to ship than metal or glass because the payload is much lower for the same amount of stuff. There are a lot of examples of the good it does in medical and elsewhere but the industry has done a horrible job of advertising the benefits.
August 26, 2022 at 5:14 am
I’m a lawyer for the federal government, and no one seems to know that everything government agencies can and cannot do starts and ends with legislation that Congress passes. That really obvious idea that would solve some basic and obvious problem? We can’t do it without legislation authorizing us to do it.
August 26, 2022 at 7:12 am
I’m a translator. A shocking number of people seem not to realize that other languages are not just like, codes for English, but have whole different systems and cultures attached.
That means context matters, translation takes time and effort, and it is a skill that you don’t automatically unlock by being bilingual.
Basic and obvious to anyone who’s thought about language in a serious way, but not everyone has.
August 26, 2022 at 8:26 am
I’m in urban planning, and most people don’t realize that the things they don’t like about where they live (traffic, ugly billboards, lack of amenities within walking distance) are more likely the result of planning and zoning rather than the lack thereof. People are always saying, “Oh, you’re a planner, well, we could really use some planning around here!” They are always shocked to hear that the built environment we experience is largely the result of 20th century land use policy, not some random accident.
August 26, 2022 at 8:52 am
I’m a physiologist & most people (even a lot of physiologists!) think that gaining or losing weight is a simple matter of the balance of calories ingested vs calories “burned”.
August 26, 2022 at 3:14 pm
Love this – please tell us, what IS the key so many are missing? (sincere question)
August 27, 2022 at 6:34 am
My PhD is in Zoology, not Physiology, so I hope Michael N Nitabach will reply with more details, but I was a T.A. for the Duke Zoology Department’s undergraduate Physiology class for several semesters back in the 1980s…
What I think Michael means is that the regulation of appetite and metabolic rate are extremely complicated. If you just reduce calorie intake, that tends to slow down your metabolism. If you just increase physical activity, that tends to increase your appetite. And almost any plan of behavior change is difficult to sustain for a long time. It’s a super complex combination of Genetics and Environment. And most of the data we have on human nutrition are based on asking people to remember what they eat, because it’s expensive to pay them to live 24-7 in a place where researchers can monitor everything they eat and drink. We know far more about the effects of diet on rodents, livestock, and companion animals because we can monitor everything they consume.
So it’s NOT simple.
August 28, 2022 at 10:32 am
What Matthew D Healy wrote is definitely a substantial part of it. It’s also true that what, how, and when during the day you eat each influence how your body metabolizes ingested food & balances storage of excess energy as fat versus burns it off in “futile” metabolic cycles (where excess energy gets transformed into heat instead of stored as fat). And it’s also true that different foods with the same caloric content (as measured using bomb calorimetry) can require different amounts of energy to digest and can also be more or less digestible (so different fractions of calories pass thru & get pooped out).
August 26, 2022 at 9:26 am
Love these answers. I’m a historian and probably the main mistake people make about the past is assuming that the past is somehow ‘knowable’ and that therefore rewriting history is wrong. In actual fact, very little is ‘known’: we construct plausible accounts with the evidence we have, but almost all evidence is subject to differing interpretations. Even if we can agree on a ‘fact’ e.g. X event happened on X date, the significance of X is always going to be up for discussion. And what we think is important to ask or know about the past always stems from present-day concerns, therefore history is always being rewritten, something a lot of people on the right of the political spectrum just don’t get. Another basic mistake is to assume people in the past were stupider or less rational than we are. They weren’t, they just had less information about certain things.
August 26, 2022 at 9:48 am
Man, Leah really does ask great questions!
August 27, 2022 at 10:52 pm
Thank you!
I’m enjoying these answers. I keep thinking about how I’d answer.
August 26, 2022 at 11:51 am
Marginal tax rates! There was a whole thread on Twitter last night where some professor in Canada said that he wrote a book and he was taxed so heavily on the profits that it set back his retirement ten years “trying to recoup the loss” (paraphrasing because I can’t remember the exact phrasing). It seemed odd.
Part of my work involves HR (in CA) and people frequently think that if they and the employer agree to it, they can just not adhere to labor law when it suits them.
August 26, 2022 at 11:57 am
I study invasive species that harm ecosystems. Most people haven’t heard of invasive species, but if they have, they generally think of them as accidentally introduced problems that are well outside of any individual person’s control. Turns out that almost all invasive plants are deliberately introduced through our landscaping (solution – find native plant nurseries) and almost all invasive reptiles/amphibians are deliberately released when people get tired of them as pets (solution – take unwanted pets back to the pet store).
August 26, 2022 at 12:56 pm
Astrophysicist here. Polling would suggest that phases of the Moon and seasons are already difficult concepts. How expansion of the Universe works (and that eternal nonsensical question: “What is the Universe expanding into?”). I’m also going to blame movies for things like loud explosions in space, and a parsec being a unit of time (yes, I know, they tried to fix that one, but the original problem isn’t going away!).
August 26, 2022 at 5:20 pm
I’m a chemist, and am always annoyed a the portrayal of “chemicals” as bad. Literally everything in the world is an element or a chemical compound. Some are bad, sure. But most things are not and there are many chemicals we can’t live without.
Also, on a slight tangent, as a woman scientist, I am also shocked at how little some male colleagues understand about the challenges women in science face. There are numerous articles that have been published in top scientific journals with data to show that women are less likely to be funded, less likely to be included as authors on papers, less likely to be cited, less likely to be promoted, etc. etc. just because they are women (controlling for other factors). Yet I still have colleagues who sit down with me and say “tell me about your experiences and the challenges you see in our area”. And then dismiss my n of 1 as an outlier.
August 26, 2022 at 5:33 pm
That for any disease and any treatment, people will belong to four groups:
1. Those who will have a good outcome with or without the treatment
2. Those who will have a bad outcome with or without the treatment
3. Those who will have a good outcome if given the treatment and a bad outcome if not given the treatment
4. Those who will have a bad outcome if given the treatment and a good outcome if not given the treatment.
In most cases, each of these four groups will be of nonzero size. The main purpose of Clinical Trials is to determine (1) the percentages in each group, (2) the confidence intervals around the percentages, and (3) how to tell which patients are most likely to benefit from the treatment.
Anecdotes mean NOTHING NOTHING NOTHING because all four groups are of nonzero size. It’s much more difficult and expensive than most people think to learn the truth.
August 27, 2022 at 10:58 am
Similarly, I just learned that there’s such a thing as a surgery regret rate. These sorts of things do seem like good things to ask about before deciding whether to get the treatment.
August 26, 2022 at 6:57 pm
I’m an engineer who specialises in wastewater treatment & water recycling for non-drinking purposes (well, I do water generally)
Most people don’t seem to realise that water recycling isn’t constrained by people’s willingness to use the water. Instead it is constrained by
1. An imbalance between supply and demand- too much water when you don’t want it or not enough when you do
2. The cost of treatment and supply is uneconomic due to current pricing models (ie it’s not that expensive to dispose of and/or there a cheaper alternative supply available)
3. Regulatory frameworks or legislation that limit use (e.g. when a utility is required to act commercially in dealings so that it can’t provide treated wastewater “ free”)
4. that recycled water actually costs real money to produce because you need to use energy and chemicals to make it safe. The better quality and more usable it is, the more expensive it is.
5. Higher quality water means a more concentrated waste stream. so you can recycle 98% of inputs if you’re irrigating tress or a turf farm, but only 70% of the inputs if you’re producing drinking water quality. All that concentated waste still needs to go somewhere.
I actually love what I do because of rather than inspite of those issues listed above. Working though the technical, social and economic problems as they intersect is good fun.
August 26, 2022 at 8:56 pm
In the field of religious studies, there is no consensus among scholars as to what the definition of religion is, and, generally, scholars do not think there can or should be such a consensus.
Religions are not all “basically the same”; however, people who practice religions not your own are, in fact, real human beings. (Ian McEwan in a different context, refers to this as “the simple truth that other people are as real as you.”)
Jesus was Jewish.
August 27, 2022 at 11:12 am
Thanks, all! These are so interesting!
As an ex-bureaucrat, I can say that most (all?) stupid hoops you have to jump were created in response to some problem. For example, at the university where I worked, in order to request a name change, you had to provide the actual document leading to your name change (such as a marriage certificate) rather than “just” a new driver license all because of that time a lady tried to change someone else’s name to her own name so it would look like she’d earned a degree.
And when you don’t know how to fill out a form because it makes no sense, do ask questions. If you can be specific, such as “do you want a or b?”, it makes it more clear to the bureaucrats who have forgotten that not everything is obvious to people who look at their forms only once in a lifetime. Sometimes they will even have an answer to “why do I have to do this?” that will make your work easier to swallow.
As an ex-typist, um, the keys on the typewriter were deliberately organized to make typing as slow as possible so that the keys wouldn’t stick when you hit them at almost the same time. We are still using that QWERTY keyboard today, but there are other keyboards available for faster typing (and for one-handed typing, and who knows what else). I have not learned any, but have heard that it is possible to be bilingual with them (switching back and forth between them with ease). (I only became bilingual in switching between a Mac and a PC during the 1990s.)
August 27, 2022 at 11:59 am
My DH does both QWERTY and Dvorak, but most recently I’ve been seeing things saying Dvorak isn’t better than QWERTY. He has no regrets and continues to use Dvorak.
August 27, 2022 at 3:28 pm
People never seem to understand why the projects I work on take so long, so many people, and are so expensive. And then sometimes still fail.
August 27, 2022 at 6:52 pm
I worked in library software. So many people don’t know they can place holds from home AND that they can freeze the hold to actually trigger later. In the meantime they’ll float up the list so it’s a shorter wait once they re-activate the hold.
August 27, 2022 at 10:57 pm
I learned that about two years ago. So magical! I prefer paper books but read so much more with Libby on my phone and being able to delay holds. It’s nice to always have a book with me when I’m waiting somewhere.