Trusting Experts

Over on the Google+, Robin Hanson asks a leading question:

Explain why people shouldn’t try to form their own physics opinions, but instead accept the judgements of expert physicists, but they should try to form their own opinions on economic policy, and not just accept expert opinion there.

(I suspect the thing he wants me to explain is not something he thinks is actually true.)

There are two aspects to this question, the hard part and the much-harder part. The hard part is the literal reading, comparing the levels of trust accorded to economists (and presumably also political scientists or sociologists) to the level accorded to physicists (and presumably also chemists or biologists). Why do we — or should we — accept the judgements of natural scientists more readily than those of social scientists?

Although that’s not an easy question, the basic point is not difficult to figure out: in the public imagination, natural scientists have figured out a lot more reliable and non-obvious things about the world, compared to what non-experts would guess, than social scientists have. The insights of quantum mechanics and relativity are not things that most of us can even think sensibly about without quite a bit of background study. Social scientists, meanwhile, talk about things most people are relatively familiar with. The ratio of “things that have been discovered by this discipline” to “things I could have figured out for myself” just seems much larger in natural science than in social science.

Then we stir in the matter of consensus. On the very basics of their fields (the Big Bang model, electromagnetism, natural selection), almost all natural scientists are in agreement. Social scientists seem to have trouble agreeing on the very foundations of their fields. If we cut taxes, will revenue go up or down? Does the death penalty deter crime or not? For many people, a lack of consensus gives them license to trust their own judgment as much as that of the experts. To put it another way: if we talked more about the bedrock principles of the field on which all experts agreed, and less about the contentious applications of detailed models to the real world, the public would likely be more ready to accept experts’ opinions.

None of which is to say that social scientists are less capable or knowledgable about their fields than natural scientists. Their fields are much harder! Where “hard” characterizes the difficulty of coming up with models that accurately capture important features of reality. Physics is the easiest subject of all, which is why we know enormously more about it than any other science. The social sciences deal with fantastically more complicated subjects, about which it’s very naturally more difficult to make definitive statements, especially statements that represent counterintuitive discoveries. The esoteric knowledge that social scientists undoubtedly possess, therefore, doesn’t translate directly into actionable understanding of the world, in the same way that physicists are able to help get a spacecraft to the moon.

There is a final point that is much trickier: political inclinations and other non-epistemic factors color our social-scientific judgments, for experts as well as for novices. On a liberal/conservative axis, most sociologists are to the left of most economists. (Training as an economist allegedly makes people more selfish, but there are complicated questions of causation there.) Or more basically, social scientists will often approach real-world problems from the point of view of their specific discipline, in contrast with a broader view that the non-expert might find more relevant. (Let’s say the death penalty does deter crime; is it still permissible on moral grounds?) Natural scientists are blissfully free from this source of bias, at least most of the time. Evolution would be the obvious counterexample.

The more difficult question is much more interesting: when should, in completely general terms, a non-expert simply place trust in the judgment of an expert? I don’t have a very good answer to that one.

I am a strong believer that good reasons, arguments, and evidence are what matter, not credentials. So the short answer to “when should we trust an expert simply because they are an expert?” is “never.” We should always ask for reasons before we place trust. Hannes Alfvén was a respected Nobel-prizewinning physicist; but his ideas about cosmology were completely loopy, and there was no reason for anyone to trust them. An interested outsider might verify that essentially no working cosmologists bought into his model.

But a “good reason” might reasonably take the form “look, this is very complicated and would take pages of math to make explicit, but you see that I’ve been doing this for a long time and have the respect of my peer group, which has a long track record of being right about these issues, so I’m asking you to go along this time.” In the real world we don’t have anything like the time and resources to become experts in every interesting field, so some degree of trust is simply necessary. When deciding where to place that trust, we rely on a number of factors, mostly involving the track record of the group to which the purported expert belongs, if not the individual experts themselves.

So my advice to economists who want more respect from the outside world would be: make it much more clear to the non-expert public that you have a reliable, agreed-upon set of non-obvious discoveries that your field has made about the world. People have tried to lay out such discoveries, of course — but upon closer inspection they don’t quite measure up to Newton’s Laws in terms of reliability and usefulness.

Social scientists are just as smart and knowledgable as natural scientists, and certainly have a tougher job. But trust among non-experts isn’t demanded, and shouldn’t be based on credentials; it is given on the basis of a long track record of very visible success. Everyone would be in favor of that.

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77 Responses to Trusting Experts

  1. J-Doug says:

    As a social scientist and a professor who teaches his students never to accept authority blindly (in matters of social science, at least), I think your final point is spot on (and more important than your first two). People have more of an incentive to accept or disregard authority in socio-economic and political matters–such as the Laffer Curve–whereas few people tie up their identity with supersymmetry or the germ theory of disease, for example.

    The obvious exceptions are evolution and global warming.

  2. edward hessler says:

    There is a large literature which shows that we are very active in forming our own ideas of how the world of physics works. Many of these turn out to be wrong to varying degrees and these were first termed as misconceptions/alternative explanations (plus more than a 100 other terms/phrases).

    Research on misconceptions also shows that they are extraordinarily resistant to change and physics professors who have taken time to interview their students or use any of the various conceptual inventories (e.g., The Force Concept Inventory) know these difficulties. A number of physics departments have their own programs/research groups that deal with physics education, e.g., the University of Maryland, University of Massachusetts, University of Washington, University of Colorado, University of Minnesota) and Harvard University physics professor, Eric Mazur pioneered an intervention program in large lecture conditions to deal with these (His research site has many useful papers on teaching with concept learning in mind.). And one Nobel prize winner, Carl Wieman, has turned from physics research to the improvement of physics education, especially at the college level, emphasizing the need for a scientific approach to science education.

    The K-12 education reform document, Benchmarks for Scientific Literacy (Project 2061, AAAS) had a chapter (The Research Base) documenting the most common misconceptions in science but it is very much outdated.

    An Internet search on misconceptions in physics (as well as chemistry, biology, earth science) will lead to many interesting and revealing papers as well as provide useful resources (inventories in particular) that can be used to improve teaching.

  3. Jason Dick says:

    Great post! Unfortunately, from learning about economics over the past few of years since this crisis hit, I’ve come to understand that the following statement simply isn’t possible:

    “So my advice to economists who want more respect from the outside world would be: make it much more clear to the non-expert public that you have a reliable, agreed-upon set of non-obvious discoveries that your field has made about the world.”

    This is because there simply isn’t an agreed-upon set of discoveries in economics, period, due to the splintering of the field, most significantly between the sometimes-named “saltwater” and “freshwater” schools. However, it seems to me that an interested observer can, without too much difficulty see which school, if any, better approximates reality. And you can do this by asking the following questions:

    1. Does this expert use a specific economic model? Can I understand this model, and confirm it predicts what this expert claims it predicts? (Usually, though not always, macroeconomic models are pretty simple.) If there doesn’t appear to be a model in use, just lots of ad hoc justifications, look out!
    2. Have the predictions of this expert stood up to reality? This is most easily tested by looking at easily-calculated phenomena, such as interest rates, inflation, GDP, etc.

    Using these criteria, it seems to me that economists such as Paul Krugman, Brad DeLong, and Mark Thoma are quite good (Greg Mankiw, not so much). Some examples of confirmed predictions since this crisis began:
    1. It was going to be a jobless recovery.
    2. The original stimulus package was too small, such that the economy was likely to continue to languish.
    3. Despite the large increase in government deficits, interest rates on government debt were likely to fall.
    4. Despite interest rates near zero and quantitative easing, inflation was likely to continue to fall.

    So it seems to me that there is a specific school of economics that has come through this crisis with flying colors. It is sad that so much of the economic profession has not.

  4. Low Math, Meekly Interacting says:

    It’s difficult to avoid a certain level of skepticism when considering the interminable and heated debates over the theories of John Maynard Keynes and Milton Friedman. Both won the Nobel Prize, and beyond that there’s little professional consensus, nor do I expect there to be. Study of the natural sciences lends itself to the quest for greater and greater accuracy, and defeat of bad ideas is a matter of experiment and consistency. The social sciences are in a more difficult position, but it appears to be exacerbated considerably by their practitioners, who not only lay claim to authority, but occasionally are called upon to shape social policies in profound ways. Had more of them been able to admit how tenuous their true grasp of real-world social phenomena was, they might not be in the position now of defending their very relevance. I look at economics, and I see the occasional prophetic scholar railing against the storm. But the field? I find it difficult to categorize. It’s social, to be sure. But science?

  5. Markk says:

    It’s isn’t hard, its simple. We have done the experiments in the physical sciences. Over and over. Millions of time we have tested and do test through engineering the models used by the scientists. Every time we use a computer, drive a car, use an antiseptic we ourselves do little tests and get a little more confidence in the people that designed them and the models that they used. There are millions and millions of examples of this. Basically there is nothing like civil, electrical or mechanical or chemical engineering in the social sciences that is integrated into societiy as much as traditional engineering. It is the engineering everybody sees that makes the scientific background of physics and chemistry so much more believable.

  6. Arun says:

    This is a problem – which experts to trust – that has occupied me on and off for the longest of times. I think good recipes here – there are no algorithms – are essential for an informed citizenry.

    1. Find out what the opposing experts say.

    2. Look at some of the literature, even if it is Greek to you. Trace out papers (using the Citation Index) to see reactions to what your expert wrote, look for agreement and dissent – don’t just rely on third parties. Get some idea of the weights on either side of a controversy.

    3. Take one small area of controversy, if you can, and study it in detail. Sometimes it becomes clear that the weight of logic is very lopsided. Try to see if you can spot which experts are presenting the whole truth, and which experts are “lawyering”.

    4. Beware of narratives that sound very plausible but don’t provide a wide view of the data. A recent example that happened to me – Fact: corporations have a lot of cash. The claim was – corporations are hoarding cash because banks are reluctant to lend after the financial crisis of 2008. On further examination – it turns out that corporations have been increasing their cash-to-overall asset ratio since the 1980s, doubling between 1980-2004; and the 2010-11 statistics are supposedly in accord with this long-term trend. ( Further-further examination – not yet done.) The danger I’m pointing out is that the narrative sounded so plausible that I might have blindly accepted it.

    5. Try to grasp the structure of the argument even when you can’t follow the substance. E.g. simple example, if you come across a pair of papers, the first of which says, I will assume this result which I will demonstrate in a subsequent paper, and then the second paper assumes something that was shown in the first paper, be very suspicious. Not necessarily anything wrong, but it doesn’t smell good. Good prevaricators manage to hide the handwaving much better, though 🙁

    6. Remember that verifying claims is typically a Polynomial Time problem; coming up with a good new theory is typically a NP-complete problem. Likewise checking up someone’s explanation for something is typically far easier than coming up with a good explanation for something. Your job is to find experts that you trust, not to become an expert.

    7. The side that talks in terms of a model is likely more right than the side that simply strings together a set of plausible arguments, unsupported by data.

    A good warm-up exercise is to examine for yourself the literature on something like cold fusion and see if you can arrive at the consensus opinion for yourself.

  7. Neal J. King says:

    The field of economics is at the level of scientific maturity that I would characterize as pre-Newtonian.

  8. kyle says:

    is this a joke?

  9. Philoponus says:

    Look, it’s not clear to me that I ever have to (or ought to) “trust” in the work of theoreticians of any ilk. “Sean Carroll believes that T” is never evidence that T is true (though it may be grounds that I should take seriously and inquire into his grounds for believing that T). We are not medieval Scholastics, counting the number of authorities who support T and the number who reject T, and concluding the higher number is likely right.

    The situation is very different in applied fields like medical research. If I have a parent slipping into Alzheimer’s, and Art Horwich (this year’s Lasker Prize winner) says intranasal insulin therapy looks very promising although we have only prelim data, I have to make a choice. I can’t replicate his research, I have to trust that his protocols are sound, and I have to decide whether to subject a failing parent to therapy that could do no good and possibly some harm. Here I have to trust and act.

  10. Ted Davenport says:

    Sean said: “Social scientists are just as smart and knowledgable as natural scientists, and certainly have a tougher job.”

    This is horseshit. Take your false humility and shove it.

  11. very surprised says:

    Economics is actually physics in disguise. Once one understands that most of economics is just partial derivatives of certain curves, it all comes together fairly quickly.

  12. Mike says:

    Arun @6,

    What a very useful post. I hope that I try and do all of these things. I was very interested in your point 4. What a perfect example of where people can go wrong. Again — good job!!

  13. Pingback: Another example of why economics is not a science | The Observer

  14. I think people confuse difficulty in comprehending theory with execution in practice. Economic theory can be dense to the uninitiated, but in general the basic mathematical description is fairly simple. One can do a lot in microeconomics without going further than linear algebra.

    In practice microeconomics is extraordinarily complex because it is difficult to define any notion of value that is universally agreed upon. So it becomes reasonable that those who practice economics can become a little defensive because there is a lot of art that is not readily translatable into theory.

    Certain experts can become indignant, but I don’t think most economists can make the bridge to generalizing their research in such a way that they can claim it as a science.

  15. John Emerson says:

    Mark Thoma:

    “There is no grand, unifying theoretical structure in economics. We do not have one model that rules them all. Instead, what we have are models that are good at answering some questions – the ones they were built to answer – and not so good at answering others.”

    Economics is more like a craft wisdom or a toolbox than like a theoretical science. This doesn’t mean it’s useless or meaningless, just that it shouldn’t claim to be like physics. I don’t think that it should be expected to be, or try to be, like physics. As said above, it’s a tougher job dealing with more difficult systems. Physicists who drop down to easier sciences sometimes do great things (Crick and Watson) and sometimes they mess up (most of theoretical economics, and the quants).

    A lot of times scientists seem to be trying to establish pecking orders rather than to understand other sciences. Physicists have been cited as doubting that biology is a science, since it fails to meet certain standards that physics can meet. According to Philip Anderson (Nobelist), quantum physicists even sneer at condensed matter physicists, of which he is one. Some of it is like

  16. John Emerson says:

    One problem not mentioned is that everything economists study is controversial and has major effects in the lives of human beings. Nobody really cares about [string theory or whatever the cutting edge field is in physics], and no one will get rich or have their life ruined if one theory wins out.

  17. I think there’s also the aspect of “what does this have to do with me?” bias between a physicist and sociologist. Most laypeople have no specific reason to care what new universe the next new telescope is going to find, but they have a lot of buy-in on expert policy on things like end of life care or employment benefits or taxes.

    Those are also the issues people are likely to have an a priori opinion of, thus expert testimony will not be the first exposure to the topic and thus more likely to cause distrust if the expert opinion is contrary to established beliefs.

  18. Gary says:

    Microeconomics is relatively close to being a falsifiable area, macro is a bit like alchemy was in Newton’s day – although Newton himself spent a lot of time on it!

    For example, they have a so called Nobel prize in economics and one year they gave it to Myrdal and Hayak simultaneously which is rather like giving two Fields medals out: one for supposedly proving a result and the other for finding a counterexample.
    At best Macro has rather too much phlogestin floating around inside of it, at it’ worse (as practiced by the so called fresh water guys, it is basically as if we all decided to do astrology only using really fancy non linear math to do the calculations,

  19. Pingback: Overcoming Bias : Physics vs. Economics

  20. Pingback: Trusting experts: the social and natural sciences divide « Entertaining Research

  21. Kaleberg says:

    If physicists argued that water runs uphill, if chemists argued that wood could not burn because it contains carbon, if biologists argued that fish cannot live underwater, then I’d trust them as much as I trust economists. In fact, I’ll cut anyone a little slack. Science and the world are full of surprises, but when the experts are consistently and repeatedly wrong, I will not deny them their hard earned disbelief.

  22. rgb says:

    “Explain why people shouldn’t try to form their own physics opinions, but instead accept the judgements of expert physicists, but they should try to form their own opinions on economic policy, and not just accept expert opinion there.”

    Not sure about the original question: I would have thought that people should try to form their own physics opinions among other things. Of course, forming informed opinions takes time, which people only have finite amounts of. Now, with physics, one has to be really interested (many of those probably end up as physicists anyway) because more often than not he/she’s opinions will not have much effect.

    Social science on the other hand, one has to be aware of. In order to live in society responsibly we have to make choices that affect the society (for example vote) or us personally. Therefore it is essential to decide which of the experts is right. For physics the stakes are not as high

  23. Jimbo says:

    Au Contraire, Monsieur !
    If there was ever a time when non-physicists should try to formulate their own opinions about the makeup & functioning of the physical world, it’s NOW.
    As of today, string theory, based critically upon SUSY, appears to be utterly incapable of predicting any aspects of the std. model; the LHC has excluded SUSY out to 700 Gev. Large extra dimensions, probed out to 7 Tev, have not manifested as mini-black holes or any other predicted processes. Most of the parameter space in which Higgsy might be hiding, has been excluded. Cutting edge theoretical ideas, such as Verlinde’s holographic interpretation of gravity, has been shown to be at odds with established falling neutron measmts. Most incredibly, the INTEGRAL satellite has recently found evidence that the real quantum gravity scale may lie an incredible 14 decades beyond the Planck scale at 10^- 49 meters.
    In short, all of the `established’ canon for physics signatures beyond the standard model appears to have fell on its collective face, after 40 yrs of waiting. This situation is unprecedented in modern physics, & we need bright, creative minds to throw down the gauntlet & introduce new ideas in the vacuum of failed ones conceived & nurtured by the physics establishment.

  24. Greg Ransom says:

    “a reliable, agreed-upon set of non-obvious discoveries”

    1. Economic coordination via central planning is impossible in an extended economy.

    2. The elimination of interest rates is impossible in an extended economy,

    3. Extended economic coordination without money & money prices is impossible.

    4. The determination of a “just price” is impossible.

    Generations of people have thought that all of these were possible — many non-economists still do.

  25. Greg Ransom says:

    There couldn’t be anything more useful than to disabuse people of the mistaken belief that it possible to centrally plan an extended economy, or that it is possible to determine a just price, or that it is possible to do away with private property and money and money prices, or that it is possible to do away with interest.

    Many of the greatest human tragedies of modern times were due to failures to grapes these surprising and useful discoveries, discoveries due to great scientists stretching back to the Spanish schoolmen.