Many historically-influential philosophers had profoundly wrong moral views or behaved very badly. Aristotle thought women were “deformed men” and that some people were slaves “by nature.” Descartes had disturbing views about non-human animals. Hume and Kant were racists. Hegel disparaged Africans. Nietzsche despised sick people. Mill condoned colonialism. Fanon was homophobic. Frege was anti-Semitic; Heidegger was a Nazi. Schopenhauer was sexist. Rousseau abandoned his children. Wittgenstein beat his young students. Unfortunately, these examples are just a start.
These philosophers are famous for their intellectual accomplishments, yet they display serious moral or intellectual flaws in their beliefs or actions. At least, some of their views were false, ultimately unjustified and, perhaps, harmful.
How should we respond to brilliant-but-flawed philosophers from the past? Here we explore the issues, asking questions and offering few answers. Any insights gained here might be applicable to contemporary imperfect philosophers, scholars in other fields, and people in general.
The question raises general concerns:
A. People versus Propositions:
Philosophers are distinct from philosophies: people are not their propositions. But thoughts say something about the thinker. Which then might be of greater concern, the person or their writings?
B. Ad hominem concerns:
Some responses to flawed philosophers seem to be attacks on the person, not on their ideas. Ad hominem attacks are often irresponsible, but are they ever appropriate? Are they appropriate if a person’s character affects their writings? Might personal moral vice relevantly impact moral philosophizing? Can it impact non-moral philosophizing?
C. Major versus Minor ideas:
Philosophers are typically known for what has come to be considered their “major” ideas. Their flaws, however, are sometimes displayed in what’s considered their “minor” writings. But what determines what’s major or minor? Quantity? Quality? Influence? That philosopher’s judgment? Moral evaluation? Is this ‘subjective,’ depending on readers’ perspectives?
D. Counterfactual correction:
Philosophies are sometimes developed from, or based on, false (empirical) information. If the thinker had better information, would their philosophy have been better?
E. Apology and Forgiveness:
Living people can apologize, pledge to do better and seek to make amends with the hope of forgiveness. Is there any way flawed (dead) philosophers can somehow “make it up” to the present or be “forgiven,” especially if their views eventually improved?
There surely are other potentially-relevant general concerns to be identified and applied.
Let’s turn to some general responses.
A. Acceptance: Take the Good, Ignore the Bad
One response is that we are all flawed, in thought and deed, and so we should focus on interesting and good aspects of flawed historical philosophers’ thought. This is especially appropriate if their writings have no apparent connection to their bad claims or behavior. We also often don’t know much about philosophers’ personal circumstances and inner life: this might make what they said or did understandable, if not excusable.
However, unless we make it clear to readers that there are bad elements and that we are ignoring them, we risk misleading or deceiving them into believing the philosopher was not flawed: e.g., students may admire a philosopher and think he must have been a paragon of virtue, when he surely was not.
The “take the good, ignore the bad” response has limits: our own flaws, if too serious, should not be overlooked (even if we wish they would), and neither should anyone else’s. What then is too serious?
B. Complete Dismissal: Boycott & Excommunication
Another response is that we just stop reading, researching and teaching offending philosophers’ writings: we boycott.
‘Zero tolerance’ policies are sometimes invoked for contemporaries, with great confidence. It’s comparable to ‘we won’t watch (or sell) any of his movies again, given what he did.’ If that has merits, so might this.
We might wonder though, what the point would be. For dead philosophers, this “punishment” is symbolic, at best. But, removing them from “the canon” might show concern for people disrespected by that philosopher: prejudice won’t be tolerated anymore.
“Ex-communication” might be too much though. Future philosophers and students won’t benefit from that philosopher’s insights, and his legacy may be ruined. It also creates a hole in the history of thought, a less-complete and sanitized version of history. This makes it more likely that offenses would be forgotten and disrupts our understanding of later thinkers who were influenced by that flawed philosopher. We might also be left with very few philosophers!
C. Historical Apologism: Judge by Past Standards
It may be unfair to hold a past thinker to present standards. Nobody can be expected to challenge all the (moral) assumptions that later generations come to regard as indefensible. Perhaps then we should partially or completely forgive these thinkers. Maybe they weren’t blameworthy for their views: given the standards of their times, they simply didn’t know any better.
This response really only works when flawed philosophers really didn’t know better. Even then, though, we might think that they should have known better. Philosophers tend to encourage critical thinking and challenging assumptions: they should better live up to that in their own lives, right?
D. Redemption: Using the Good to Defeat the Bad
This response, like (A) above, involves acceptance, but instead of overlooking the bad, we display it and try to use the good aspects of a philosopher’s thought to diagnose and correct it. Concealing the bad is misleading and potentially deceptive to people not familiar with that philosopher: they might think he was like a saint, when he was really often a scoundrel. Had the philosopher realized his good claims were in tension with his bad claims, he might have rejected the bad in favor of the good. But he might not have: he could have favored the bad over the good., Or he could have just ignored the tension. We can only speculate about how some philosopher would have responded to criticisms he maybe never encountered.
But there are not always positive elements within a philosophers’ writings to critique bad claims, so optimism isn’t appropriate for all flawed philosophers.
Redemption also has opportunity costs. Lesser-known philosophers (especially minorities) who have ideas comparable to (or perhaps better than) famous philosophers may be overlooked in our efforts to redeem them.
There are surely other possible responses; some might overlap with those discussed. Responsibly applying any of these responses requires detailed knowledge of a philosopher’s life and philosophy, as well as the application of general ethical concerns.
 For a Kant-focused discussion of the issues of this essay, see Victor Fabian Abundez-Guerra’s “How to Deal with Kant’s Racism — In and Out of the Classroom,” Teaching Philosophy, 41, 2. May 19, 2018, pp 117-135. His article inspired this more general discussion here.
 Of related interest is comparable concerns in responding to any bad behavior and claims of scholars and researchers in other fields, past and present. Some of our discussion below is potentially applicable: e.g., if the wrongdoing is totally unrelated to the area of research, this is likely of a lesser concern – and wouldn’t give rise to the question of whether we should use that research – than, say, social scientists developing factual information about some social problems, yet wrongfully act in ways that contributes to those social problems or privately disparage the people affected by those problems. When empirical or scientific issues have moral dimensions, their researchers and scholars can be seen as likely having moral motivations for their factual investigations. In that way, they approach having philosophical perspectives on the issues, and so their flaws raise similar concerns to philosophers’ flaws.
 It may be tempting to create a sharp division between philosophers and their writings, adopting the maxim “the author is dead,” that is, that we should treat the author’s background and intentions as irrelevant when deciding the merits of their work. But if Nietzsche is correct in viewing philosophy as an author’s autobiographical memoirs, this division may be wrongheaded. See §6 in Friedrich Nietzsche’s Beyond Good and Evil, Walter Kaufman (trans.), Vintage Books,  1989.
 Charges of “hypocrisy” are sometimes ad hominem attacks, since whether a person follows the principles he or she advocates, in itself, says nothing about whether these principles are true or reasonable: e.g., if a vocal critic of shoplifting is found to have shoplifted, that gives no reason to think that shoplifting is OK. When controversial principles or claims are advocated for, however, that might suggest that their advocates don’t really believe them, or that they don’t really think there are good reasons for their principles (and, perhaps, that there are no such reasons). Alternatively, this might merely suggest that good principles are often hard to follow, even for those who identify these principles and recognize their goodness.
 For a discussion of contemporary ethicists’ unethical behavior, see Oliver Burkeman’s, “This column will change your life: why are ethicists so unethical?” The Guardian, November 16, 2013.
 What we consider the philosophers’ main ideas may not be what those philosophers considered their major ideas, or what past generations considered their major ideas.
 Heidegger became disillusioned with Nazism later in life and some philosophers argue that Kant eventually grew out of his racist views. Should this influence our attitudes towards their earlier views? See Pauline Kleingeld’s “Kant’s Second Thoughts on Race,” The Philosophical Quarterly, 57, 229, 2007, pp. 573-592.
 This is roughly the strategy Robert Louden takes when he writes “Kant’s writings do exhibit many private prejudices … but Kant’s theory is fortunately stronger than his prejudices, and it is the theory on which philosophers should focus.” See his Kant’s Impure Ethics: From Rational Beings to Human Beings, Oxford University Press, 2000, p. 177.
 As a potential example, is there a connection between, say, Frege’s anti-Semitism and his logic? If not, then perhaps there is no good objection to studying or using his insights on logic.
 If we ignore the bad in a philosopher’s collective writings, however, it is not clear what principled ground we would have for construing that edited set of writings as that thinker’s philosophy. This is especially the case if the philosopher in question worked extensively on the bad and believed them to be of the utmost importance, even more important than what we consider their good ideas. E.g., Kant who offered over seventy courses in anthropology and geography (where many of his racist views are found), but only twenty-eight in moral philosophy. By continuing to construe the remaining work as that thinker’s philosophy, we not only potentially mislead new philosophers, but also just interpret history incorrectly: e.g., Charles Mills argues that if we cut out the bad, or “sanitize” Kant’s philosophy, then the remainder would quite simply not be Kant’s philosophy, as it is not what Kant actually thought. See his “Kant’s Untermenschen” which proposes that Kant categorized human beings not just as ‘persons’ but also as ‘subpersons.’ In Andrew Valls (ed.), Race and Racism in Modern Philosophy, Cornell University Press, 2005, pp. 169-93.
 It’s worth noting that a complete boycott is something that no individuals or groups have the power to do. At best, the offensive-to-many philosopher would remain in memory as a philosopher-who-used-to-be part-of-the-generally-accepted canon, since the philosopher would surely retain some admirers.
 See, for instance, online discussions concerning contemporary philosophers accused of sexual harassment. Jenny Saul Sheffield suggests “If you can avoid teaching/discussing [these philosophers], that may be the best strategy.” She then goes on to qualify this statement by mentioning, “If you just need a representative of some family of views, you can avoid the whole issue by choosing someone else. If you really need to discuss [the accused’s] view, then you discuss [the accused’s view].” In light of this, discussing a less known thinker in lieu of the problematic favorite may serve as a way of diversifying the philosophical canon. Some discussions are here: “How to Discuss Searle, etc.” Feminist Philosophers blog, March 28, 2017, and “John Searle may be guilty of sexual harassment…” Leiter Reports blog, March 28, 2017.
 In light of the #MeToo movement, the idea of boycotting the work of sexual predators has resurfaced. For discussions on this, see Nicole Hemmer’s “How to think about consuming art made by sexual predators,” Vox, January 9, 2018, and Chuck Klosterman’s “On Boycotting Woody Allen’s Films,” The New York Times Magazine, March 14, 2014, among other discussions.
 Habermas has a similar thought to this when engaging with the “Historian’s Debate” in Germany. Habermas however, seems to believe that in order to restore the dignity of historically oppressed populations, we should not brush aside the past, but instead keep it alive. He writes,
“There is the obligation incumbent upon us in Germany … to keep alive, without distortion, and not only in an intellectual form, the memory of the sufferings of those who were murdered by German hands … [I]f we were to brush aside this Benjaminian legacy, our fellow Jewish citizens and the sons, daughters, and grandchildren of all those who were murdered would feel themselves unable to breathe in our country.”
See his “On the Public Use of History,” The New Conservatism, 1989, p 233.
 Whether dead people can be harmed or wronged is, of course, an interesting and controversial philosophical issue.
 See note 15 above. The concern here is similar to the concern of “whitewashing” U.S. History if a teacher fails to discuss chattel slavery, segregation, genocide of Native Americans, etc.
 Recall that we are discussing thinkers that have something (indeed, a lot) positive going for them: they are a well-known thinker for good reason. For any thinkers who don’t have this going for them — nearly everything they have to say is bad and wrong — it’s fine to cut them out and ignore them. Elizabeth Barnes discusses the intellectual and moral costs of discussing offensive views that have little to nothing in their favor in her “Arguments That Harm – and Why We Need Them,” Chronicle Review, February 18, 2018.
 Concerning contemporary people, few people who are “progressive” concerning one issue are comparably “progressive” about all other important issues for which progressive positions are most reasonable: there is a general collective failure of “intersectionality.” This is not an ad hominem attack: it’s the observation that we all tend to have (true) and reasonable beliefs about some (moral) issues, but false and unreasonable beliefs about others (and that we tend to resist revising those false and unreasonable beliefs). In this way, most of us are similar to the historical philosophers discussed in this paper. How should we respond to them, and us? For discussion, see an 80,000 Hours podcast with Will MacAskill, “Our descendants will probably see us as moral monsters. What should we do about that?” January 19, 2018.
 Miranda Fricker discusses this in regards to epistemic injustice when she mentions that sexists of the past “were not culpably at fault until they were in a position to know better,” in her Epistemic Injustice: Power and the Ethics of Knowing, Oxford University Press, 2009, p. 100.
 Kant for instance, likely did know better as he “was an avid reader of travel reports of all kinds, written by explorers… He warned repeatedly on the unreliability of such sources, but rely on them he did.” See Thomas McCarthy’s Race, Empire, and the Idea of Human Development. Cambridge University Press, 2009, p. 49.
 Although not focused on epistemic or intellectual blame, see Neal Tognazzini’s and Justin D. Coates’ “Blame”, The Stanford Encyclopedia of Philosophy, Spring 2016, Edward N. Zalta (ed.). For an intellectual blame-focused discussion, see Sanford C. Goldberg’s “Should have known.” Synthese, 194, 8, 2017, pp. 2863-2894 and his To the Best of Our Knowledge: Social Expectations and Epistemic Normativity, Oxford University Press, 2018.
 For that matter, it is not obvious we should hold anyone who studies ethics professionally (e.g., priests) to the same standards as the general population. Eric Schwitzgebel discusses this question in his blog post “Should Ethics Professors Be Held to Higher Ethical Standards in Their Personal Behavior?”
 One might imagine, for instance, Kant using his Categorical Imperative in order to dismiss his racist beliefs, or Mill using his principle of utility to defeat his endorsement of colonialism.
 One can begin by looking at Charles Mills’ “Kant’s Untermenschen” in Andrew Valls (ed.), Race and Racism in Modern Philosophy, Cornell University Press, 2005, pp. 169-93. Mills’ The Racial Contract also deals with this issue. See also Emmanuel Chuckwudi Eze’s “The Color of Reason: The Idea of “Race” In Kant’s Anthropology” in Postcolonial African Philosophy: A Critical Reader,” in Emmanuel Chuckwudi Eze (ed.), Blackwell, 1997, pp. 103-140. Also Robert Bernasconi’s “Kant as an Unfamiliar Source of Racism” in Philosophers on Race: Critical Essays, Julie K. Ward and Tommy L. Lott (eds.), Blackwell, 2002, pp. 145-66.
 If the bad and good aspects of a philosopher’s thought are conceptually related, meaning that claims about one area have logical implications for claims about the other (and vice-versa), then they might be in tension. Analyzing and speculating on how philosophers reconciled this tension could help us avoid their mistakes in the future. David Livingstone Smith suggests that when populations dehumanize others there is cognitive dissonance between that population’s supposed beliefs (e.g. all people deserve respect) and their desired practice (e.g. to enslave or exterminate a minority). In which case, “the dissonance between theory and practice was resolved by denying the humanity of the oppressed” namely by attributing a less than human essence to the oppressed. See Smith’s Less Than Human: Why We Demean, Enslave, and Exterminate Others, St. Martin’s Press, 2011, p. 3.
 See note 13 for more discussion on this.
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About the Authors
Victor Fabian Abundez-Guerra is a Ph.D. student in philosophy at the University of California, Riverside. His interests are in philosophy of race, moral responsibility, and Mexican philosophy. https://victorabundezguerra.wordpress.com
Nathan Nobis, Ph.D. is an Associate Professor of Philosophy at Morehouse College, Atlanta, GA. He is the author of Animals & Ethics 101, co-author of Thinking Critically About Abortion, a co-author of Chimpanzee Rights and author or co-author of many other articles, chapters, and reviews in philosophy and ethics. www.NathanNobis.com