Clifford’s razor
William of Ockham (sketch) 1341
William of Ockham was a 14th century English Franciscan friar famous for not quite saying entia non sunt multiplicanda praeter necessitatem (‘entities must not be multiplied beyond necessity’). This is perhaps the most common formulation of what has become known as ‘Ockham’s razor’ or the ‘law of parsimony’. He did however say (ie write) numquam ponenda est pluralitas sine necessitate (‘plurality is never to be posited without necessity’) and frustra fit per plura quod potest fieri per pauciora (‘it is futile to do with more things that which can be done with fewer’) – which are pretty close.
So it is perhaps ironic that the Franciscan friar himself interpreted it as meaning that ‘no plurality should be assumed unless it can be proved by reason, or by experience, or by some infallible authority’ (emphasis added) – like the Bible & other Christian sources.
William Clifford (1845-1879)
Five hundred or so years later another William applied another razor to the kind of belief which infallible authority thrives on. William Clifford’s 1877 essay The ethics of belief declared that it is wrong always, everywhere, and for anyone, to believe anything upon insufficient evidence. By ‘wrong’ Clifford clearly meant ‘morally wrong’.
He tells the story of a ship-owner who suspected his ship might not be seaworthy, but managed to overcome his doubts – not by having her overhauled and refitted, but by trusting in Providence. He let her sail and she sank in mid-ocean. Was he guilty of the death of the crew? Undoubtedly. He sincerely believed his ship was safe, but he had acquired his belief not by honestly earning it in patient investigation, but by stifling his doubts.
What if the ship had actually been sound? Clifford argues the ship-owner would have been just as guilty – not of manslaughter of course, but just as guilty of believing something he had no right to believe, because the origin of his belief was unsound. So he would have been just as guilty of endangering the lives of his crew.
Clifford also argues that guilt accrues not just from any action arising from an unjustified belief, but from the belief itself. In practice it is impossible for a belief to be entertained without having any effect in the world, if only because each unjustified belief makes it easier to believe the next one. Unjustified belief is insidiously corrupting:
Every time we let ourselves believe for unworthy reasons, we weaken our powers of self-control, of doubting, of judicially and fairly weighing evidence. We all suffer severely enough from the maintenance and support of false beliefs and the fatally wrong actions which they lead to, and the evil born when one such belief is entertained is great and wide. But a greater and wider evil arises when the credulous character is maintained and supported, when a habit of believing for unworthy reasons is fostered and made permanent. If I steal money from any person, there may be no harm done from the mere transfer of possession; he may not feel the loss, or it may prevent him from using the money badly. But I cannot help doing this great wrong towards Man, that I make myself dishonest. What hurts society is not that it should lose its property, but that it should become a den of thieves, for then it must cease to be society. This is why we ought not to do evil, that good may come; for at any rate this great evil has come, that we have done evil and are made wicked thereby. In like manner, if I let myself believe anything on insufficient evidence, there may be no great harm done by the mere belief; it may be true after all, or I may never have occasion to exhibit it in outward acts. But I cannot help doing this great wrong towards Man, that I make myself credulous. The danger to society is not merely that it should believe wrong things, though that is great enough; but that it should become credulous, and lose the habit of testing things and inquiring into them; for then it must sink back into savagery.
The harm which is done by credulity in a man is not confined to the fostering of a credulous character in others, and consequent support of false beliefs. Habitual want of care about what I believe leads to habitual want of care in others about the truth of what is told to me. Men speak the truth of one another when each reveres the truth in his own mind and in the other’s mind; but how shall my friend revere the truth in my mind when I myself am careless about it, when I believe things because I want to believe them, and because they are comforting and pleasant? … It may matter little to me, in my cloud-castle of sweet illusions and darling lies; but it matters much to Man that I have made my neighbours ready to deceive. The credulous man is father to the liar and the cheat; he lives in the bosom of this his family, and it is no marvel if he should become even as they are. So closely are our duties knit together, that whoso shall keep the whole law, and yet offend in one point, he is guilty of all.
He defends his thesis against a number of potential objections, clarifying when it is sound or unsound to believe something on someone else’s authority, and establishing principles for avoiding systematic scepticism for example about the future or the past. He sums up as follows:
We may believe what goes beyond our experience, only when it is inferred from that experience by the assumption that what we do not know is like what we know.
We may believe the statement of another person, when there is reasonable ground for supposing that he knows the matter of which he speaks, and that he is speaking the truth so far as he knows it.
It is wrong in all cases to believe on insufficient evidence; and where it is presumption to doubt and to investigate, there it is worse than presumption to believe.
It is worth considering why Clifford sees it as not just unsound or unwise to believe on insufficient evidence, but as morally wrong. There is a ‘sin’ which, depending on the context, could be one of commission or of omission. The ship-owner has either deliberately misled the crew into believing he had done everything he should have done to ensure the ship was seaworthy; or failed in a duty of care. In his position he should have been aware of the possible consequences of suppressing his doubts, including the false beliefs he could have created in people he was exposing to danger.
Perhaps the most celebrated attack on Clifford’s thinking came from yet another William – William James (1842-1910): psychologist, pragmatist philosopher, and brother to novelist Henry James. So it is to William the third that we now turn.
© Chris Lawrence 2008
thinking makes it so 
dear Chris,
I just read your fine summary of Clifford’s argument. I believe his position is far too monolithic and would stop life in its tracks, especially when you realize that belief can be taken in two senses.
One is for the credulity of a proposition or the evidence for a hypothesis making a theory scientifically acceptable. Perhaps this sense is also right in terms of laws that are broken and evidence for guilt pronounced for the likes of that ship-owner. Clifford is completely right in such cases.
But the second sense of the word “belief” is closer to trust, which is the human capital that makes society itself possible, let alone the good faith that under-girds morality.
Without trust the most basic economic transaction would break down. How could I believe that you would hand me an article after I gave you the money for it? Should I first ask for the article and then pay you because of a lack of trust? Look at the number Osama Bin Laden has done on us in the airports. Billions of dollars have to be spent and millions of hours of productive time wasted because we now cannot trust each other.
Clifford makes a categorical mistake when he uses belief in the second sense to undermine human responsibility. A matter of faith, the source of being trust-worthy and responsible (for the crew of a ship one owns) is used immorally and selfishly, to not check the sea-worthiness of the vessel. The ship-owner values his money more than the lives of his crew, a good indication why regulation is necessary. Clifford uses a category of knowledge in a moral relational situation, where responsibility and trust-worthiness are required.
Clifford makes an analogy between stealing something and believing something without evidence, making both equally evil. With that he equates faith, a source of morality, with an immoral act.
In that latter situation, when someone says, “Trust me” our suspicions should immediately be aroused and verification should be sought. This kind of social capital called trust is mostly unconscious.
I think when William James presents his three kinds of decisions living, forced, and momentous, he is also getting at the fact that trust is the social capital that makes life, love, and even thought possible.
To turn Clifford’s argument against him: how can someone not believe in God, when the whole universe exists as evidence. You and I certainly did not create it. It is a gift we have received from above.
peterkrey
2 March 2011 at 7:45 pm
Dear Peter,
Thank you so much for responding in such depth. You may not be surprised though that I do not 100% agree with what you say.
I agree with the distinction you refer to between the two senses of ‘belief’ – or at least between belief and trust. But I do not think Clifford conflates the two senses, as I think his arguments principally apply to belief in the first sense. And are we really dealing with three concepts here or just two?
If there are three they might be:
(1) Belief in the first sense, epitomised by a scientific hypothesis backed (or not) by evidence.
(2) Belief in the second sense, which is closer to trust.
(3) Trust itself.
But I am not sure I can see any real distinction between (2) and (3).
I accept what you say about trust as the human capital which makes society possible, but I see this as trust (3), not a kind of belief (2) which is significantly different from trust (3).
So I don’t think Clifford is making a category mistake, because in the case of the ship-owner he is principally talking about belief (1), not belief (2) or trust (3). The ship-owner believes (1) the ship is sea-worthy in spite of having insufficient evidence for that belief. Yes he may be abusing the trust (3) his crew is placing in him, but that is not the main point Clifford is making. Clifford is saying the ship-owner is (morally) wrong to believe (1) the ship is sea-worthy. He is not saying (what may also be justifiable) that the ship-owner is (morally) wrong to abuse the trust (3) the crew place in him to ensure the ship is sea-worthy. I am not saying he would deny this. But he seems to me to be saying something rather more interesting than that – something which James, for all his rhetoric, seems to miss. (See Which Will to believe?, Getting pragmatic, Better believe it, As if, as if etc.)
As for your final point, I do not see how the rhetorical question about belief in God turns Clifford’s argument against him. I think I can see how someone who already believes (1) in God’s existence can then go on to believe (1) that God created the universe. But I would be surprised if someone who does not already believe (1) in God’s existence, would seriously consider the existence of the universe as evidence in support of a belief (1) in God.
Your point about Osama bin Laden is interesting. I too lament what the destruction of trust has done to air travel. But I also wonder if the world would have become such a dangerous place if he and his followers had considered applying Clifford’s principle to their own beliefs.
Thank you again for the conversation.
Chris.
Chris Lawrence
7 March 2011 at 2:49 pm
Oops. I missed out a phrase from the middle of that quote, but you get the idea…
Jordan Pickering
20 October 2008 at 10:45 am
Hmm. As Lewis points out, the philosophical question (whether miracle is a possibility) needs to be settled first. Our senses are not infallible, and so even immediate experience can be illusion. If our philosophy excludes the supernatural, then any alternative natural explanation (even highly unlikely ones) will do. He says:
“Many people think one can decide whether a miracle occurred in the past by examining the evidence ‘according to the ordinary rules of historical enquiry.’ But the ordinary rules cannot be worked until whether miracles are possible, and if so, how probable they are. For if they are impossible, then no amount of historical evidence will convince us.” etc.
Do, if you deeply hold that miracles cannot happen, you will never be led to believe that they do or did. It’s worth a read.
Jordan Pickering
20 October 2008 at 10:38 am
Thanks again Jordan, & for the Golden Rule response.
I will add ‘Miracles’ to my reading list. My superficial take has so far been that the issue is not so much whether miracles can happen but whether they do happen. So a bit more depth would be good.
Chris.
Chris Lawrence
19 October 2008 at 9:22 am
The Lewis quote comes from a chapter that follows much careful preparatory work, including an argument that Hume’s invocation of probability in ruling out miracles begs the question. [For probability to be a meaningful idea, it needs to depend upon the uniformity of nature. Miracles are by definition suspensions of uniformity. So asking whether miracles can happen is the same question as whether or not nature is uniform. One cannot therefore use a tool that presupposes uniform nature to answer a question about uniformity of nature itself].
Well, I won’t do him any justice by brutalising his arguments here, but ‘Miracles’ is a thoroughly wonderful book, and well worth a read, even just for his writing craft. You may not (and need not) find his demonstration of the necessity of the supernatural convincing (although I’d love to hear your views on his argument). You can derive much that is useful from the book by viewing the world from a thoughtful supernaturalist’s eyes, to see how the picture hangs together. He is a must-read Christian author, not least because he used to be an atheist, and so is less prone to the inevitable straw-manning that comes from being an outsider to your ‘opponent’s’ world.
Jordan Pickering
18 October 2008 at 9:49 pm
Thank you for taking the time to respond, & for the response itself. Lots to think about.
I agree the question of what constitutes sufficient & insufficient evidence is very important, & it’s one I want to address at some point. At the moment I’m focusing on the nub of William James’s objection – trying to work out to what extent I agree & to what extent I don’t.
I must confess to not having read much CS Lewis beyond the gates of Narnia, so I’ll probably miss crucial context. But my immediate response to your first quote is that I’m not yet sure I’d accept his special pleading. I am quite surprised he doesn’t see the incarnation as ‘intrinsically improbable’ (if I’m reading correctly); and very surprised that an explanation that ties together disparate phenomena like laughter, logic, fear of the dead and ‘our knowledge that it is somehow good to die’ should for that very reason warrant a lower level of justification. It suggests that Lewis must have independent prior reasons for thinking phenomena like these are somehow connected, and that therefore an explanation that covers all of them is, other things being equal, to be favoured.
Your second point, about the ‘gravity of the moral action’, gets pretty close to one of my principal reasons for starting this thread. It’s the question whether one can really justify believing that something is the case, purely on the basis that good comes as a result of that belief. That’s not the whole of James’s objection to Clifford’s principle, but it is part of it. By ‘believing that something is the case’ I don’t mean something like believing we should behave in such and such a way. I mean literally believing that something is true about the universe – eg that there is a god, rather than believing there isn’t. James argues that there is a kind of good which accrues from sincere belief in the ‘religious hypothesis’ which is not achievable without it.
My current hunch (& I mean hunch – I’m nowhere near an answer yet!) is that it would be difficult to claim that it was ultimately morally wrong to believe something on the sole justification that greater good came from believing it than from not believing it – if this was really true. On the other hand I do not understand yet how it can be really true that there is a ‘better’ good that can only come this way, and so for that reason I remain sceptical about James’s objection.
As for your ‘cavalier’ point – of course I agree: ‘Tread softly, because you tread on my dreams’. But the kind of beliefs I’m talking about claim an element of universality, so they exclude for example private spiritual experiences understood as such.
Thank you again for some very valuable feedback. I hope it’s not the last.
Chris.
Chris Lawrence
17 October 2008 at 8:25 pm
Chris
This is a good piece, and while I am yet to read William’s response, my own response is this:
I agree in principle with what he puts forward, but with the acknowledgement that the word ‘insufficient’ must bear a lot of weight. The quality of the evidence that we provide is important, but what is ‘sufficient’ also depends on the gravity of the moral action that we plan to perform on the basis of the belief in question.
Firstly, in regard to quality of evidence: At the end of CS Lewis’ chapter on ‘The Grand Miracle’ (i.e. the incarnation as the key to understanding all the others) in his book ‘Miracles’ he demonstrates how the historical event of the incarnation serves to explain and interpret a number of key experiences in nature (such as principles and patterns of descent and reascent, selectiveness, vicariousness, etc.). He says:
“Whether the thing really happened is a historical question. But when you turn to history, you will not demand for it the kind and degree of evidence which you would rightly demand for something intrinsically improbable; only that kind and degree which you demand for something which, if accepted, illuminates and orders all other phenomena, explains our laughter and our logic, our fear of the dead and our knowledge that it is somehow good to die, and at one stroke covers what multitudes of separate theories will hardly cover for us if this is rejected.”
So, the question of what is sufficient in terms of evidence is all important, but often complicated.
Secondly, in terms of the gravity of the proposed action, it has long been my view that there is much in the Christian faith that should be believed with a high degree of certainty, but other things that can not be so securely believed. We all must believe things as true although we cannot know for certain. Even a scientism that denies all metaphysics must do so on metaphysical grounds. As long as we recognise the degree of doubtfulness that adheres to our various beliefs, we are able to temper our actions accordingly.
So, although I agree with Clifford in many respects, it would be foolish if we are too cavalier with his razor. It is always easier to perform surgery on someone else’s body than your own (to over labour the razor idiom), and so we may too quickly cut away at other people’s beliefs without fully understanding their basis.
Jordan Pickering
17 October 2008 at 2:39 pm