The Illicit Process from
Possibility to Actuality
Excerpt from: An Atheist's Values
by Richard Robinson

[Page 212-3]:

... People sometimes think that the proposition that 'we are fallible' entails its own contradictory in the following way: 'Assume that we are fallible; it follows that we may be wrong in saying that we are fallible; and from this in turn it follows that we are infallible.'

The flaw here is that it is false that the second consequence follows. From 'we may be wrong in saying that we are fallible' it does not follow that 'we are infallible'. 'Are' never follows from 'may be'. From possibilities alone one cannot rightly conclude to facts. We may call this fallacy the illicit process from possibility to actuality....

... But I want before leaving the topic to warn you against a certain misuse of this doctrine, a misuse which was perhaps committed by Oliver Cromwell on a famous occasion. In his letter of 3 August 1650 to the General Assembly of the Kirk of Scotland, Cromwell wrote: 'I beseech you, in the bowels of Christ, think it possible you may be mistaken.' What was his purpose in thus reminding his opponents of the fallibility of man? One good reason for doing this is to persuade your adversary not to suppress the publication of views opposed to his own; and that Cromwell had this purpose in mind is suggested by his mentioning, elsewhere in the letter, that the Kirk had been suppressing his papers whereas he had been publishing the Kirk's letters to him. On the other hand, the letter never unequivocally says that this is the purpose of the famous reminder; and some parts of it suggest that he was using it in another way, namely to insinuate that 'since you may be wrong, you are wrong and I am right'. One part of it implies that he knows he is right because he feels the grace of God upon him, and that way of thinking seems more typical of the man. Anyhow, the argument that 'since you may be wrong, you are wrong and I am right', whether or not Cromwell was guilty of it, is utterly fallacious and a damnable misuse of the doctrine of human fallibility. It is another case of the illicit process from the 'may be' to the 'are'. The undoubted fact that you may be wrong is an excellent reason for your allowing free speech to your opponents. But it is no reason for them to claim that you are wrong; for, from the truth that all men are fallible, nothing follows about who is in the right in any particular controversy. It would be better to say: 'I beseech Christ to make me think it possible that I am mistaken.' The fallibility principle should make us not merely patient of criticism, but eager for it.

This fallacy is often committed by lawyers crossexamining witnesses. 'But you could be mistaken, could you not?', they ask. Of course he could be mistaken, because he is fallible; but it does not follow that he is mistaken. It is a hard question to reply to. If you say 'No, I could not be mistaken', you appear to claim infallibility. But if you say 'Yes, I could be', you appear to withdraw your statement, or at least some of the force of it. Perhaps the best reply is 'One always can be mistaken, but one sometimes is not', or simply 'I could be, but I'm not'.

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