Sometimes to stop arguing with someone, we say: “You have a right to your opinion.”
But is that true? May we believe whatever we want to believe?
In his essay “The Ethics of Belief,” British mathematician and philosopher W.K. Clifford (1845–1879) argues that the answer is “no.” He claims that “it is wrong always, everywhere, and for anyone, to believe anything upon insufficient evidence.”
By “evidence” Clifford seems to mean experiences and reasoning that bear on the truth of a belief: evidence is information relevant to determining whether a belief is likely true or false.
If Clifford is correct, we don’t have a right to believe whatever we want: indeed, it can be morally wrong to hold certain beliefs, if we lack good evidence for them.
This essay explains Clifford’s view.
1. The Ship Case
To make his case, Clifford first asks readers to imagine a shipowner who has evidence that his ship might need expensive repairs. He doesn’t want to pay that expense so, through wishful thinking, he convinces himself of what he wants to believe. Clifford writes:
In such ways he acquired a sincere and comfortable conviction that his vessel was thoroughly safe and seaworthy; he watched her departure with a light heart, and benevolent wishes for the success of the exiles in their strange new home that was to be; and he got his insurance-money when she went down in mid-ocean and told no tales.
If the shipowner’s belief that his vessel was seaworthy had been based on good evidence, the sinking would have been unfortunate, but he wouldn’t have been blameworthy. We blame him for this outcome, though, because his belief was formed contrary to the evidence available to him. He should have known better, or at least he should have believed better: his believing against the evidence was wrong.
2. All Beliefs Matter
The shipowner’s failure seems especially bad because the outcome was so disastrous. But Clifford thinks that the ethical principle against believing on insufficient evidence applies to all beliefs, even those that seem unimportant. He writes:
No real belief, however trifling and fragmentary it may seem, is ever truly insignificant; it prepares us to receive more of its like, confirms those which resembled it before, and weakens others; and so gradually it lays a stealthy train in our inmost thoughts, which may someday explode into overt action, and leave its stamp upon our character for ever.
No belief is isolated, Clifford argues: we’re always in the process of building our own intellectual characters. Sloppy or motivated reasoning, even about something like whether our favorite team is likely to win a game, puts us in danger of developing bad mental habits that will corrupt our thinking about more important things. So believing without or against the evidence always imposes unacceptable risks to ourselves and others.
3. True Beliefs as a Public Resource
Although we tend to think that our beliefs are our own private business, Clifford maintains that “belief… is ours not for ourselves but for humanity” in the same way that air and water are public resources.
The term “epistemic commons” (“epistemic” means related to knowledge) refers to the shared knowledge and trustworthy practices of belief formation we all collectively rely on. False and unjustified beliefs in the epistemic commons are a kind of pollution. Just as it’s wrong to dump toxic waste into a river used for drinking water, it’s wrong to degrade the epistemic commons by failing to exercise proper stewardship over our beliefs.
We might also have duties to improve the epistemic commons by learning more, and developing better reasoning habits, just as we have duties of beneficence toward those in need. And unlike air and water, which can only be made so pure, there’s no limit to how much the epistemic commons can be improved.
4. Applying the Ethics of Belief
How many of our beliefs are ethically held, according to the ethics of belief? Many people have confident beliefs about politics, religion, philosophy and science. If we’re being honest, we should probably conclude that many of these beliefs don’t satisfy Clifford’s standards: our evidence often isn’t that strong.
On the other hand, Clifford doesn’t say much about what counts as “sufficient evidence.” What he says in his essay is consistent with thinking that the available evidence sometimes leaves room for reasonable disagreements.
Does this mean that we must be frantically collecting evidence all the time? Not necessarily; according to Clifford, we’re always free to suspend judgment until we have enough evidence:
“But,” says one, “I am a busy man; I have no time for the long course of study which would be necessary to make me in any degree a competent judge of certain questions, or even able to understand the nature of the arguments.”
Then he should have no time to believe.
When we don’t know much about a topic, it’s responsible to not have firm views on it. We might learn more about it, or decide that our time is better spent some other way and continue suspending judgment until we learn more. Recognizing when we don’t have enough evidence to form an informed opinion requires discipline, but waiting until we have good evidence before forming beliefs is smart and wise.
Some say we must have confident beliefs to act on, but Clifford observes that we can “act on probabilities” even where there’s too much uncertainty to form confident beliefs; so, “…we have no reason to fear lest a habit of conscientious inquiry should paralyze the actions of our daily life.”
Beliefs are ethically significant: they influence how we behave, and serious wrongdoing can often be traced to believing without adequate evidence. If Clifford is right, then many of us, and perhaps all of us on occasion, are falling short, morally. We might all be more like the shipowner than we’d like to admit. Fortunately, we can all be better by resolving to proportion our beliefs to the evidence.
 Clifford, 1886, p. 175.
 Theories of “epistemic justification” attempt to identify what we should and should not believe, what we are justified in believing, from an epistemological point of view, where the concerns are seeking truth, reasonable beliefs and knowledge.
An influential theory of epistemic justification called evidentialism is the view that, from an epistemological point of view, we should believe what, and only what, our evidence supports.
Clifford’s “ethics of belief” claims that there is an ethical obligation that our beliefs be justified according to the evidentialist standard and so based on strong, sufficient evidence. For an introduction to evidentialism, see Thomas Metcalf’s Epistemology, or Theory of Knowledge.
 Clifford, 1886, p. 164.
 Clifford does not explicitly appeal to any particular ethical theory in arguing that it’s morally wrong to believe on insufficient evidence, but his position does fit well with the ethical theory “consequentialism” which holds that we are obligated to do what produces the best overall consequences: after all, Clifford does argue that believing on insufficient evidence tends to have bad consequences: see Shane Gronholz’s Consequentialism and Utilitarianism for an introduction to consequentialism. Clifford’s position can be supported, however, by a variety of ethical theories: theories that focus on virtue and vice are also especially applicable; see Virtue Ethics by David Merry.
 Clifford, 1886, p. 169.
 Clifford, 1886, p. 170.
 Hrishikesh Joshi develops the concept of the “epistemic commons” in his Why It’s Ok to Speak Your Mind, 2021.
 For discussion of the issue of how to respond to disagreements concerning whether some a belief is true or false, especially when the people who disagree seem to be roughly equally-informed and with equally strong evidence for their views, see Jonathan Matheson’s The Epistemology of Disagreement. The basic question is this: if we have such disagreements, should we remain confident and continue believing what we believe, lose confidence and perhaps come to accept the belief(s) of the person(s) we disagree with, lose confidence and suspend judgment on the issue (and perhaps research it more), or something else?
 Clifford, 1886, p. 176.
 Clifford, 1886, pp. 177-178.
Clifford, W. K. 1886. “The Ethics of Belief.” Originally published in Contemporary Review, 1877; reprinted in William K. Clifford, Lectures and Essays, ed. Leslie Stephen and Frederick Pollock. Macmillan. 1886, pp. 163-205. (The “Ethics of Belief,” and excerpts from it, is widely reprinted and reposted here; also here in PDF).
For Further Reading and Listening
Critical Thinking: What is it to be a Critical Thinker? by Carolina Flores
Epistemology, or Theory of Knowledge by Thomas Metcalf
Consequentialism and Utilitarianism by Shane Gronholz
Virtue Ethics by David Merry
Expertise: What is it to be an Expert? by Jamie Carlin Watson
The Epistemology of Disagreement by Jonathan Matheson
Indoctrination: What is it to Indoctrinate Someone? by Chris Ranalli
Conspiracy Theories by Jared Millson
Pascal’s Wager: A Pragmatic Argument for Belief in God by Liz Jackson
Moral Luck by Jonathan Spelman
Download this essay in PDF.
About the Author
Spencer Case has a doctorate in philosophy from the University of Colorado Boulder, where he is currently a lecturer. He hosts Micro-Digressions: A Philosophy Podcast and does a lot of writing, academic and otherwise. SpencerCasePhilosophy.com