The Legitimacy Crisis of Arguments from Expert Opinion: Can’t We Trust Experts?


Recent disputes (Mizrahi in Inform Logic 33(1):57–79, 2013; Mizrahi in Inform Logic 36(2):238–252, 2016; Mizrahi in Argumentation 32(2):175–195, 2018; Seidel in Inform Logic 34(2):192–218, 2014; Seidel in Inform Logic 36(2):253–264, 2016; Hinton in Inform Logic 35(4):539–554, 2015) on the strength of arguments from expert opinion (AEO) give rise to a potential legitimacy crisis of it. Mizrahi (Inform Logic 33(1):57–79, 2013; Inform Logic 36(2):238–252; Argumentation 32(2):175–195, 2018) claims that AEO are weak arguments by presenting two independent arguments. The first argument (i.e., the argument of unreliable experts) is that AEO are weak arguments because empirical studies show that expert opinions p do not make p significantly more likely to be true. The second argument (i.e., the argument of biased experts) is that AEO are weak arguments because empirical studies show that expert opinions are susceptible to the kinds of cognitive biases that novice opinions are susceptible to. In this paper, I intend to argue that Mizrahi’s two arguments both fail because of inconsistency, irrelevance, and insufficiency. Nevertheless, Mizrahi’s arguments help to evaluate AEO better by expanding the relevant critical questions.

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  1. 1.

    For more examples, see also Mizrahi (2013, pp. 57–58).

  2. 2.

    Presumptive arguments are also recognized as plausible arguments by Rescher (1976) that are provisionally acceptable, but defeasible, subject to new incoming information in a case.

  3. 3.

    “Critical questions” are a tool for evaluation of an argument fitting an argument scheme. According to Walton (1997, pp. 208–213; 2008, pp. 92–93), there are six general critical questions of AEO: expertise question, field question, opinion question, trustworthiness question, consistency question, and backup evidence question.

  4. 4.

    Some might raise an objection like this: the standard view of the strength of AEO is that AEO are just potentially acceptable or strong arguments. Some AEO might be weak (i.e., fallacious); some AEO might be acceptable or even strong. In other words, the strength of AEO varies on a case by case basis and is evaluated by means of critical questions. Therefore, the debate of AEO presented by this paper is a pseudo-debate, which means that it would be unimportant to take part in this debate. In reply to this potential objection, I would like to make some points. First, the standard view presented by this paper is based on many textbooks mentioned above, while the standard view of the strength of AEO raised by this objection seems to need more justification. Second, it would not be a practical choice for people to accept the standard view raised by this objection, because it means that people should not even provisionally accept any AEO until the argument is carefully evaluated. Third, even if the standard view raised by this objection could be justified, it is still important to pay close attention to the debate presented in this paper. Because even for some AEO, which can be evaluated as strong arguments by means of critical questions, Mizrahi does not think that they are really strong and argues that there is a dilemma in the evaluation of AEO (2013, pp. 67–72). In this sense, Mizrahi challenges the very foundation of the evaluation of AEO established by theorists (e.g., Walton 1997; Wagemans 2011), and that is also why this paper says that there is a potential legitimacy crisis of AEO. To sum up, this debate is not a pseudo-debate, and it is worth participating in it if you are concerned about the legitimacy of AEO.

  5. 5.

    The research Mizrahi cites is about expert political predictions, such as forecasts regarding national security or trade, international relations, welfare policy (see Tetlock 2005).

  6. 6.

    In Mizrahi’s usage, “expert judgments” and “expert opinions” seem to be interchangeable and synonyms.

  7. 7.

    For more examples, see Mizrahi (2018, pp. 180–183).

  8. 8.

    I understand that many scholars use ARS (i.e., acceptability, relevance, and sufficiency) to evaluate arguments, but in this paper, I will use CRS (i.e., consistency, relevance, and sufficiency) instead. In some usages, one of the conditions of unacceptability is that premises are explicitly or implicitly inconsistent, which means that consistency is a sub-concept of acceptability. In other words, if an argument is inconsistent, its premises would be unacceptable. Mizrahi’s argument is arguably inconsistent, I think that the term “inconsistency” can point out the problem more explicitly.

  9. 9.

    The argument reconstruction presented by Seidel (2014, p. 213) is slightly different from the version here, but I think they both correctly characterize Mizrahi’s argument.

  10. 10.

    Seidel argues that Mizrahi does subscribe to (A4) by analyzing one of Mizrahi's examples in detail (2013, pp. 213–216). Besides, even if Mizrahi tries to do all scientific and empirical research by himself, he will also need to rely on AEO. Modern science is cooperative work, because scientists have to build on the work of those who have preceded them, and research has been increasingly done by teamwork. For more discussion, see Hardwig (1991).

  11. 11.

    If Mizrahi does not agree with this point, he will have the responsibility to convince people that experts tend to form their opinions arbitrarily.

  12. 12.

    After all, the purpose of scientific research is not purely following procedures but obtaining meaningful findings.

  13. 13.

    In fact, Mizrahi (2013, pp. 73–74) has emphasized that AEO are not only defeasible but also weak (i.e., fallacious).

  14. 14.

    Note that Mizrahi also argues that there is a “dilemma” in the evaluation of AEO by presenting a distinction between AEO and arguments from evidence. One of the critical questions about AEO is the “backup evidence question”: is the expert’s assertion based on evidence? And the so-called dilemma is: if the answer to this question is “yes,” then the argument is not AEO but an argument from evidence; if the answer is “no,” this argument is likely to be weak. See Mizrahi (2013, pp. 67–71).

  15. 15.

    I admit that when experts “present” their predictions or therapy under some circumstances, they may simply give the results without elaborating the supporting evidence (e.g., they are asked to introduce their findings briefly in a short conversation or interview), which seems like just presenting mere opinions. However, it does not mean that experts “make” their predictions or perform (i.e., their thinking processes) without appealing to evidence.

  16. 16.

    The structure of my criticism here is slightly different from the structure of my criticism on Mizrahi’s first argument in Sect. 3. The former shows that the “overall argument” of Mizrahi’s second argument is arguably irrelevant, while the latter shows that the “sub-argument” of Mizrahi’s first argument is arguably irrelevant.

  17. 17.

    It would be unconvincing to say that when people use AEO in everyday life, they tend to invoke expert opinions answered to some psychological tests.

  18. 18.

    Are expert opinions 2 biased like expert opinions 1? In other words, are experts during their own research vulnerable to pretty much the same cognitive biases that experts participating in experiments are vulnerable to? It depends on the findings of further studies. Here I just emphasize the difference between expert opinions 1 and expert opinions 2.


  1. Bolger, F., and G. Wright. 1992. Reliability and validity in expert judgment. In Expertise and Decision Support, ed. F. Bolger and G. Wright, 47–71. New York, NY: Plenum Press.

    Google Scholar 

  2. Cavender, N.M., and H. Kahane. 2009. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life, 11th ed. Belmont, CA: Wadsworth.

    Google Scholar 

  3. Chen, A. 2016. Seeing Into the Future: Does Philip Tetlock Hold the Key to Accurate Predictions? The Chronicle of Higher Education.

  4. Copi, I.M., C. Cohen, and K. McMahon. 2014. Introduction to Logic, 14th ed. London: Pearson Higher Education.

    Google Scholar 

  5. Fanelli, D. 2010. “Positive” Results Increase down the Hierarchy of the Sciences. PLoS One 5 (4): e10068.

    Article  Google Scholar 

  6. Fanelli, D., and W. Glänzel. 2013. Bibliometric Evidence for a Hierarchy of the Sciences. PLoS One 8 (6): e66938.

    Article  Google Scholar 

  7. Goodwin, J. 2011. Accounting for the Appeal to the Authority of Experts. Argumentation 25: 285–296.

    Article  Google Scholar 

  8. Govier, T. 2014. A Practical Study of Argument (Enhanced, 7th ed. Boston, MA: Wadsworth.

    Google Scholar 

  9. Hardwig, J. 1991. The Role of Trust in Knowledge. The Journal of Philosophy 88 (12): 693–708.

    Article  Google Scholar 

  10. Hargens, L.L. 1975. Patterns of Scientific Research. Washington, DC: American Sociological Association.

    Google Scholar 

  11. Hinton, M.D. 2015. Mizrahi and Seidel: Experts in Confusion. Informal Logic 35 (4): 539–554.

    Article  Google Scholar 

  12. Mizrahi, M. 2013. Why Arguments from Expert Opinion are Weak Arguments. Informal Logic 33 (1): 57–79.

    Article  Google Scholar 

  13. Mizrahi, M. 2016. Why Arguments from Expert Opinion are Still Weak: A Reply to Seidel. Informal Logic 36 (2): 238–252.

    Article  Google Scholar 

  14. Mizrahi, M. 2018. Arguments from Expert Opinion and Persistent Bias. Argumentation 32 (2): 175–195.

    Article  Google Scholar 

  15. Rachlinski, J.J., C. Guthrie, and A.J. Wistrich. 2011. Probable Cause, Probability, and Hindsight. Journal of Empirical Legal Studies 8: 72–98.

    Article  Google Scholar 

  16. Rescher, Nicholas. 1976. Plausible Reasoning. Assen-Amsterdam: Van Gorcum.

    Google Scholar 

  17. Seidel, M. 2014. Throwing the Baby Out with the Water: From Reasonably Scrutinizing Authorities to Rampant Scepticism about Expertise. Informal Logic 34 (2): 192–218.

    Article  Google Scholar 

  18. Seidel, M. 2016. The Real Struggle: An Objective Notion of Expertise? Informal Logic 36 (2): 253–264.

    Article  Google Scholar 

  19. Tetlock, P.E. 2005. Expert Political Judgment. Princeton, NJ: Princeton University Press.

    Google Scholar 

  20. Tetlock, P.E., and D. Gardner. 2015. Superforecasting: The Art and Science of Prediction. New York, NY: Crown Publishing.

    Google Scholar 

  21. Wagemans, J.H.M. 2011. The Assessment of Argumentation from Expert Opinion. Argumentation 25: 329–339.

    Article  Google Scholar 

  22. Walton, D. 1997. Appeal to Expert Opinion. University Park, PA: Pennsylvania State University Press.

    Google Scholar 

  23. Walton, D., C. Reed, and F. Macagno. 2008. Argumentation Schemes. New York, NY: Cambridge University Press.

    Google Scholar 

  24. Walton, D., & Koszowy, M. 2014. Two Kinds of Arguments from Authority in the Ad Verecundiam Fallacy. Paper Presented at the 8th Conference of the International Society for the Study of Argumentation (8th ISSA), Amsterdam, Netherlands.

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This work was supported by the Major Program of National Social Science Foundation of China (Grant No. 18ZDA031). As a visiting Ph.D. student fellow (September 2018–September 2019) at the Centre for Research in Reasoning, Argumentation and Rhetoric (CRRAR) at the University of Windsor, I would like to express my great appreciation to Prof. Douglas Walton, Prof. Hans Hansen, Prof. J. Anthony Blair, Prof. Jianjun Zhang and CRRAR Student Fellow Michael Andrew Yong-Set for their valuable suggestions during the development of this research work. I would like to thank Prof. Yun Xie, Dr. Wai-man Kwok, and the anonymous reviewers for their helpful feedback on earlier drafts of this paper. I also would like to thank Prof. Christopher Tindale, Waleed Mebane, Harmony Peach for their useful comments on my presentation about this paper at CRRAR. Finally, I would like to offer special thanks to my supervisor at CRRAR—Prof. Douglas Walton (1942–2020). He is no longer with us, but continues to inspire me with his passion and dedication in the field of argumentation. 

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Liao, Y. The Legitimacy Crisis of Arguments from Expert Opinion: Can’t We Trust Experts?. Argumentation (2020).

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  • Arguments from authority
  • Arguments from expertise
  • Arguments from expert opinion
  • Expert opinions
  • Expert judgments