Aren't expert at and in the same in this case

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I am a cardiologist myself. From my perspective:

Expert at: person who often makes and implements decisions, with good (measurable) outcomes far exceeding an occasional bad one.

Expert on: person who knows all (or most) the published/reported data on a particular topic.

These categories are not mutually exclusive. If you're seeking medical help, you'll aim at the Expert at.

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This post is so full of bias I cannot help but wonder if it's actually a "trick question" trying to elicit responses ;-).

"A prosperous and successful plumber is an expert at plumbing. Someone who is a good source for accurate information on plumbing is an expert on plumbing."

They are not mutually exclusive.

"More generally, an expert at a topic is someone who has gained the most attention, praise, income, and so on via their association with the topic. But this may not be the best expert on that topic."

Of course not.

"He may have succeeded by not giving the most accurate information, but by telling people what they want or expect to hear, or by entertaining them."

But an expert on a topic might succeed for the same reasons? Because they are funny or good looking or...

"We often rely on the heuristic of looking to an expert at a topic, when what we want is an expert on a topic."

As noted above, they are not mutually exclusive and in instances where they diverge, we might in fact want *both*.

"In fact, most of the people we see being labeled as "experts" are primarily experts at topics. For example, TV talking heads discussing topic X are usually people who have made a successful career in X. We may see a general talk about war, or a CEO talk about business."

Really?! I've noticed just the opposite. Frequently the people labeled experts on TV are experts on the topic, not experts at the topic.

"But it a rare field where the best way to succeed is to always be completely honest with everyone about everything."

Hard to refute that statement considering how absolute it is. I don't believe I know of a living human that is completely honest with everyone about everything. In the context of this discussion I'd be concerned not only with honesty on the part of an expert, but equal with cognitive bias.

"We could greatly benefit from better ways to determine who is really an expert on a topic. Prediction markets are one possibility."

Finally something we can agree on.

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Actually Phil, I'm pretty sure that many theologians don't differ detectably on how their beliefs cash in from most atheists.

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Expert at baseball: Plays well.Expert on baseball: Knows lots of statistics.

Expert at religion: A theologian.Expert on religion: An atheist.

Expert on animal behavior: An ethologist.Expert at animal behavior: A cat.

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I don&#39t agree that experts at are the ones usually consulted. It varies from field to field. It is the lack of balance that is the problem.

For example in the fields Innovation and Entrepreneurship, experts on predominate. And this limits effective policy making.

We need a balance of advice from both experts at and experts on - both have their merits.

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I suggest a third alternative.

- Expert on: Knows all about it.- Expert at: Can do it really well.- Expert in: Has a lot of success while doing it.

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If the people who picked sports commentators understood this difference the world would be a much better place.

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I don't think lying/marketing is the best explanation for a gap between experts at and experts on in most situations, including plumbers. I know something about plumbing, just because I'm mechanical and interested, though I would not consider myself anywhere near an expert on it. But my expertise *at* it is far smaller still, because I while I understand the principles of how plumbing works, I've never attempted any more than minor fixes. I'm also large and have fairly average finger dexterity and arm strength for a person my size, and probably less patience than average. In attempting to do a few plumbing jobs myself, I've discovered that while I knew what to do, actually getting various pieces apart without breaking them was big fat PITA. I mostly don't do that anymore. My point is not that I know more than a random professional plumber (I don't), merely that it is obvious to me that many of the skills necessary for them to succeed are incidental to the topic, and to decision such as whether your pipes need to be completely replaced. Someone who is physically disabled could well be the best person to make the latter decision, but they won't be the best person to actually replace your pipes.

Let's take another subject I know even more about. I'm an owner of a print shop. I know a lot about the capabilities of presses, and about the chemistry and mechanics involved in making them work. I can often make correct decisions about the effect of an unusual adjustment that skilled operators cannot. In some ways I'm more of an expert *on* presses than they are. But if I tried to actually run the press tomorrow, I'd be lucky to produce 20% of the work that my best operators do. They not only have some physical skills that are superior to mine, they have practice at doing the work every single day, and have developed a rhythm. Lying or marketing is not a significant part of their success (except to the extent that they might get me to believe that some PITA job is actually impossible), but there's still a pretty big gulf between their expertise at, and my expertise on.

Coaching sports would be another good example. Plenty of the best coaches never played their sport at the highest levels, because they simply did not have the physical gifts required.

In any case I don't think this is purely a distinction of successful vs. skilled, although that may be one dimension. I think it's also about two different skills, one which involves immediate performance and is easier to measure, and one which involves pure knowledge and is harder to measure.

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So, is there a good generic way to distinguish between experts at and on? Most externally-available measures (length of publication list, credentials, position, honors received) are meaningful, but are also subject to being gamed--we probably all know people in our fields who publish a lot of papers relative to their actual contribution in the field, and people who publish few papers, but with a lot of value per paper. Similarly, credentials (PhD from NameDroppingUniversity) tell you something, but maybe not as much as you'd like to know. And position might be a matter of good connections or networking skills or even nepotism.

Sometimes, evaluations from other experts who're familiar with their work are the best solution. Other times, there's some objective measure that can be used, though probably any measure will have a certain susceptibility to be gamed.

It seems like prediction markets could help here if there were some people who knew enough to do a good job with the evaluation, and if they knew who they were. (That is, if you're the assistant of the cardiologist with a steller reputation and a graveyard full of mistakes nobody knows about, you could make lots of money predicting future failure.) But this clearly is a hard kind of thing to evaluate, even for relative insiders--look at how tenure decisions sometimes get made!

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Sorry about the misattribution, I looked at the name above instead of the name below the comment.

I think I now have a better idea of what Robin means by "expert at" and "expert on". The distinction seems to be between those that are successful and those that are skilled. That wasn't (and isn't) my intuitive interpretation of his terms, but the original post makes more sense to me in that light.

I took exception to the terms expert at and expert on perhaps because it reminded me of the opinion some people have in my field (physics) that theorists are somehow more "pure" than experimentalists.

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"The gulf between experts on and experts at for a particular field may tell us about the level of (dis-)honesty needed to succeed in that field."

I'm not sure what you mean by this statement, could you clarify please?

Yes! Robin said that experts "at" would be those successful in the field. If the experts "on" are not very successful (which would be the case if the "at" and "on" were very different) that means that there is a set of additional skills that experts "at" have, beyond knowledge of the field.

The most obvious skills to explain the gulf are people skills, or the ability to lie/market well. If we have a profession where a good lie helps the expert "at" (say, plumbing or real estate) and if the gulf between them and experts "on" is wide, then we can suspect that lying plays a big role in that separation.

Other skills that might explain the gulf - ambition, drive, lack of social snobbery, intuition - are not quite so convincing, as there should be many experts "on" who could acquire them easily, if the incentive is there. But lying is a skill you will not acquire unless you practice it, so is the best candidate if the gulf is large.

PS: I did not write the "pipes" comment, but your response seems quite close to Robin's initial point: those who are good "at" a subject are not the ones you want to call, unless you can use incentives to get them closer to experts "on".

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"Matthew, if someone claimed you needed to replace your pipes so that they would not burst, what kind of expert would you want to evaluate that claim?"

OK, sticking to the example of plumbing.

It would depend on the context. If I got a call from a telemarketer offering me a great deal on replumbing my house, I would ignore it. If a friend of mine, who happens to be a plumber, warns me that my original plumbing was ineptly installed and it really should be redone, I'd be inclined to trust him. If I'm having minor plumbing problems (low water pressure, leaky faucet, etc) and the plumber I contact tells me that it's going to be a very expensive fix, I would probably get a second opinion. If available, I might look for reviews (there are online and offline venues for this), or I might ask for recommendations from friends or family.

"The gulf between experts on and experts at for a particular field may tell us about the level of (dis-)honesty needed to succeed in that field."

I'm not sure what you mean by this statement, could you clarify please?

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Yann Martel also seems to think he provides a vital public good. There is no cost to claiming that to be the case, an incentive to claim it regardless of whether or not it is true and no reliable method I've heard of for determining who is actually providing a "public good" in this manner (for all I know someone's output might be a negative externality on us) and to what extent.

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Nobody receives a direct private benefit from philosophers. Philosophers provide more of a public good. When an idea is good, the positive externalities are immeasurable. When an idea is wrong, the negative externalities are equally immeasurable.

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Usually I explain my distaste for e.g. academic "bioethics" by saying "ethicists write mainly for an audience of other ethicists". Thanks to this post, I can now put it more clearly: Practicing engineers who care about people tend to become experts at the ethics of their profession, but ethicists who publish papers for other ethicists merely become expert at sounding wise. And what the Singularity Institute would like to see is experts at AI ethics, who will probably not go by the job title of "AI ethicist".

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