This was originally written in a March 2012 email:
Having a bit of knowledge about physics is important to most fields.
For example: tennis, chess, hockey, baseball, architecture, chemistry, biology, cooking, cleaning, building computers, building chairs, and so on.
The amount of physics knowledge needed for basic competence in this fields is small: the large majority of people in our culture have enough already.
You don't see people trying to heat their food in the freezer.
You don't see people losing tennis tournaments because they were confused about physics.
You don't see people doing chemistry experiments using only water and expecting each portion of water to transmute into the right chemicals because they want it to.
So, people take for granted having some understanding of physics as background knowledge. That knowledge still matters and it's still correct to say physics has a lot of reach even if people take it for granted.
If you get this basic physics stuff wrong, you can be really screwed. All sorts of stuff can go horribly wrong. Getting it right does matter a lot.
In general you don't need to know the details of quantum physics. That has less reach. It's quite important for some stuff like building nanometer-scale computer chips. But you don't need to know any quantum physics to win a tennis tournament or cook dinner or even to build a skyscraper.
To do basic science you do need to know some physics, but often not quantum physics, and often not any physics that goes beyond the background knowledge your average scientist will have and get right. If they messed up the physics they need, it could easily invalidate all their experiments in their field and make all their conclusions wrong, but in practice this rarely comes up because they don't get it wrong.
There are people who get a lot of basic physics wrong. We call them superstitious or gullible or stuff like that. It matters. But they are a minority. And a lot of the people watching science TV shows or getting fooled by bending spoons or talking about "crystal energy" or "dreamcatchers" aren't actually getting physics wrong, they are making different kinds of mistakes like they think it helps provide meaning for their life and they intentionally don't think about whether the physics is right or not.
Epistemology is a lot like physics in this regard. A relatively small amount of epistemology knowledge is relevant and important to pretty much every human endeavor. It matters to tennis, chess, hockey, baseball, architecture, and all the rest, same as with physics.
And our culture has some good quality knowledge of epistemology which people take for granted and routinely use.
But, contrary to physics, most have large mistakes in their basic epistemology background knowledge. There are widespread mistakes in our culture. And they don't just affect some special minorities that stand out, they affect 99%.
The result? All sorts of stuff goes wrong, and people don't know why or sometimes don't even know something went wrong.
People do lose tennis tournaments due to bad epistemology. That's actually common. Top people in all types of competition face significant psychological issues. They have to keep the right kind of mindset and focus to play their best. And what happens is they get to the finals and make a mistake. Then they make 5 more mistakes. Then, some people will set it aside and continue to play their best. But other people will get frustrated and have the wrong attitude to mistakes and let it "rattle" them, and will "lose focus" and start playing worse and making more mistakes they wouldn't normally make if they were relaxed in a low pressure situation, or wouldn't make if they weren't frustrated with previous mistakes.
Sometimes these problems dealing with mistakes decide a match. Better attitudes to mistakes and learning, and better understanding of their mind and emotions -- better philosophical knowledge -- could have won the match.
Sometimes players come back the next year, get in a similar situation, but then get past it and win this time. They thought hard about it and improved their epistemological knowledge (and some other knowledge too). Without knowing the name of the field. Without having the benefit of a lot of already-known and useful stuff in the field. They have to re-invent some stuff, and pick some up in bits and pieces from advice from their coach and sports/competition-related books and so on.
Some people never get past these mental issues and never become champions. That's common too. It's hard to reinvent enough epistemology and pick it up from scattered places. More people fail at this than succeed.
Epistemology comes up, and sometimes goes wrong, in all sorts of more mundane situations too. People get frustrated while playing a video game and throw the controller at the TV and break it, or just feel bad. People get stuck playing a video game and don't improve. People fight with their friends when playing a team video game and blame each other for letting the team down. Bad epistemology (in the background knowledge of our culture that people take for granted) contributes to these problems and good epistemology could address them.
And epistemology comes up, and goes wrong, when scientists start talking philosophy and trying to draw philosophical conclusions from their work.
Just like there are some places where physics reaches more (e.g. building GPS devices) and more advanced physics is important, there are also places where epistemology reaches more and more advanced epistemology is important.
Without physics well beyond the background knowledge in our culture, you're going to have a lot of problems building a GPS device. The background knowledge isn't even close to good enough.
And without more advanced knowledge of epistemology, you're going to design schools wrong. Education is an area where epistemology very heavily reaches. The background knowledge about epistemology in our culture is faulty, but the error rate with some of the "more advanced" knowledge (like explicit versions of induction, empiricism, justificationism and other stuff you can read in philosophy books) is a lot worse.
It's a bit like using superstition to build a GPS device. It's so wrong that you make a compete and utter mess of things.
That is, by the way, why our schools are "failing". (They don't even know what succeeding would be and are judging be the wrong criteria. But our schools do happen to be bad according to better criteria too. FYI US schools are far better than all the asian countries though.)
So there are various areas where epistemology is extra relevant. You don't just need a bit, you need lots. Everything has to do with learning, but some stuff more than others.
Epistemology heavy topics include: education (including lots of parenting stuff), morality, stuff to do with organizing knowledge (like programming or organizing a library), stuff to do with brains, stuff to do with how people or animals or computers or anything think or learn or create knowledge, stuff to do with evolution, stuff to do with ideas or types of ideas (like the distinctions people draw between emotions vs theories vs values vs guesses, etc), qualia, stuff to do with fallibility, errors, mistakes, sources of error, good explanations, judging explanations, methods of interpreting observations, scientific methods (b/c the point of science is to create knowledge, so the methods for doing that are methods of creating knowledge, methods in epistemology).
When scientists try to do science to address questions about how people think and live, and how that compares with animals, and the consequences for morality, they are straying especially heavily into epistemology in multiple ways and going far beyond what cultural background knowledge can be expected to handle (sort of handle, but actually fail a fair amount). When their epistemology is grossly false, they make multiple large mistakes per substantial idea in these areas, and so all their conclusions are crap.