Bias in the Classroom

Imagine I’m a professor who is going to lecture my students on global warming. Further assume that after carefully looking at the evidence I conclude that there is a 60% chance that global warming is true. So if I was the only one to lecture on global warming I would devote 60% of my lecture to evidence in support of the theory and 40% to evidence opposed to it.


But now imagine that I know that most of my students will be taught about global warming in other classes. Further assume that all the other professors at my college are 100% certain that global warming is true. These other professors, therefore, will only present evidence in favor of global warming. To cause students to get as unbiased a view as possible of global warming (from my prospective) shouldn’t I devote my entire lecture to criticizing global warming theory?


Imagine a professor has some ideology such as libertarianism or Marxism that is unusual at his college.  The professor has this view because after looking at the evidence he decides it provides the best explanation of how the world works.  The professor thinks that 20% of an unbiased education would consist of learning his ideology.  But the professor knows that students won’t encounter his ideology outside of his classroom.  Doesn’t this mean that to help the students get what the professor believes is an unbiased education the professor should devote far more than 20% of his lecture time to discussing his ideology?

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  • Barkley Rosser

    Presumably we are dealing with a tenured professor here who has the luxury, more or less (as there are still questions of merit pay, not to mention perks or lack thereof), so that the prof can contemplate the question from the standpoint of a high-minded pursuit of inculcating true (and “unbiased”) thinking in students.

    Given that, the general question is interesting. Unfortunately, I have problems with the examples. Thus, there are many degrees, so to speak, and shades of belief regarding global warming. Very few now argue that there is no global warming at all. Some others say, yes, there is global warming, but humans are a relatively unimportant part of causing it. Still others say, yes, humans are a part of causing it, but it is not necessarily a bad thing, might even be a good thing (lower winter heating bills and all that), so nothing needs to be done. Yet others say, yes, it is happening, and humans are probably a significant input to it, and, yes, it will be harmful, but given some sets of possible estimates of effects and discount rates, not too much should be done about it, or maybe we should work to adapt to it. And finally we have all the various groups who think that much should be done about it, with this varying substantially.

    And, regarding libertarianism or Marxism, these are hardly the only alternative, heterodox schools of economic thought besides mainstream neoclassicism. Should one not present all the heterodox schools that are not receiving representation from one’s colleagues, or only push the one that one is particularly convinced of?

  • Daniel Janzon

    By going 100 % on one view to compensate for the other professors 100 % bias it seems to me you lose your credibility. If you think the probabilities are 60/40 in favor and want to transmit this impression to the student, you should devote 60 % in favor and 40 % against. Maybe it boils down to the question “is it most important to ensure that the students have a 60/40 proportion of facts, or a 60/40 estimate of the truth values?”.

    By the way, your posts exemplifies the discussion in the Feb 18 post Politics is the Mind-Killer 🙂

  • Matthew


    I’m not sure if your “mind killer” comment was intended tongue-in-cheek or not. I find this particular post by James Miller to be extremely interesting and relevant. The question of how heavily to argue for particular positions based on a perception of bias in the overall discussion is quite important, in my view.

  • Robin Hanson

    Each side biases their presentation of an issue and justifies it as correcting for the biased presentations of the other side.
    1) On average each side is biased to not listen enough to the other sides, and so assumes its position is the only “unbiased” one.
    2) Each side assumes that the students will just believe whatever they are told, instead of critically evaluating the arguments.
    3) Each side ignores the preferences of those paying their salary, and assumes they can make this choice based on their personal preferences.

  • Hal Finney

    Ideally, teachers would try to give their students some exposure to the arguments on both sides, even if they personally favor one side or the other. They should know that in the larger world, students will eventually hear about arguments on the other side, and it would be better to provide them with as much relevant information as possible within the classroom environment, where issues can be discussed in detail.

    If however you believe that students are getting a erroneous, one-sided presentation, then I think it would be appropriate to make an effort to present the other side. But you should explain to the students that you are doing this. Tell them that you do see value in the orthodox view being presented at the college, but that on balance you disagree, so you will devote your efforts to presenting the other side so that students will be exposed to these other arguments. Then if a student asks you, professor, which arguments from the orthodoxy do you support? You can answer honestly, albeit perhaps briefly, and explain your own views on the balance between the sides.

  • Barkley Rosser

    There is a rather curious thing that can go on here also. It may be that in a world of multiple heterodoxies or heresies, a heterodox individual might give more attention to another heterodoxy that is in some dialectically related to their own as its opposite. Thus, I have a suspicion that the Austrian School group of economists at George Mason probably spend much more time talking about the views of their extreme ideological opposites, the Marxists, than do most conventional, mainstream economists, for many of whom Marxism is a dead irrelevancy. But important elements of Austrian thought, buy von Mises and Hayek in particular, were developed out of the “socialist controversy” in very specific battles with various Marxist opponents. And, Austrians like to point out their role in the intellectual/ideological triumph over the Marxists.

    It is a bit like how until various Gnostic texts were found in deserts during the last century or so, many of the officially heretical Christian doctrines were only known by the writings of those who criticized them.

  • Eliezer Yudkowsky

    “Each side biases their presentation of an issue and justifies it as correcting for the biased presentations of the other side.” Yeah, that pretty much sums it up. I think that “There’s no excuse for bias” is a good general heuristic. People need to learn to be passionate about things that are only 80% certain.

  • EthanJ

    If the other professors at the school think global warming is merely 75% true, but they cover it exclusively (100%), then your contrarian professor would be appropriate to over-weight his own classroom discussions the opposite direction.

    But as the post is presented, the other professors accept global warming 100%. They are not over-weighting their presentations by exclusively covering global warming. So our professor should limit his presentations to his own 60%-40% assessment. If the distribution of opinions on global warming among relevant faculty at this university is sufficiently large that the collective assessment would be highly accurate, then students are best served by an education that reflects that assessment. Being the only person on the faculty to skew their coverage of the issue would skew the result.

    Part of the problem is that our hypothetical professor is over-confident. He assumes, without reason, that his own assessment of global warming is more accurate than that of his peers, when in truth he is just as human. He prefers to substitute his own judgment for that of the larger university community.

  • Gordon Worley

    This reminds me of what I find to be the main fault of adversarial courts: it’s the job of plaintiff and defendant to be as biased as possible in their own favor, and the judge or jury must pick out the truth from the arguments. It’s not about unbiased truth finding, but passionate arguing towards one’s biases.

  • Phil

    >it’s the job of plaintiff and defendant to be as biased as possible in their own favor …

    That’s not a fault, that’s a virtue. A lawyer might believe that an argument in his client’s favor is biased or untrue — but he might be wrong, to the detriment of his client.

    Suppose the lawyer, believing argument X to be a bad one, advances it anyway, and it convinces the judge. Should the lawyer not have advanced it? Why should he have assumed that his reasoning was better than the judge’s?

    The system we have now rewards a lawyer for advancing a subtly-wrong argument, but punishes him for an argument that’s so obviously wrong and biased that it peeves off the judge or jury. That seems to me to be quite reasonable.

    The “unbiased truth finding” should be left to the judge and jury, and not the lawyers.

  • Alex Linhares

    Personally, I favor the fruitcake approach: be honest with yourself, present what you believe–but only after due mention of those nasty imbecils that are obviously dead wrong.

    And, of course, prepare for the worse in your teaching career.

    Here’s to the fruitcakes!