MS 475-476 (1903) - Lowell Lecture VIII

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Upon this same principle, if two hypotheses present themselves, one of which can be satisfactorily tested in two or three days, while the testing of the other might occupy a month, the former should be tried first, even if its apparent likelihood is a good deal less.

It is a very grave mistake to attach much importance to the antecedent likelihood of hypotheses, except in extreme cases; because likelihoods are mostly merely subjective, and have so little real value. Every hypothesis should be put to the test by forcing it to make verifiable predictions. A hypothesis on which no

that considering the remarkable opportunities which they will cause us to miss, in the long run attention to them does not pay

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verifiable predictions can be based should never be accepted, except with some mark attached to it to show that it is regarded as a mere convenient vehicle of thought,— a mere matter of form.

In an extreme case, where the likelihood is of an unmistakably objective character, and is strongly supported by good inductions, I would allow it to cause the postponement of the testing of a hypothesis. For example, if a man came to me and pretended to be able to turn lead into gold, I should say to him, “My dear sir, I haven't time to make gold.” But even then the likelihood would not weigh with me directly, as such, but because it would become a factor in what really is in all cases the leading consideration in Abduction, which is the question of Economy,

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— Economy of money, time, thought, and energy.

It is Prof. Ernst Mach who has done the most to show the importance in logic of the consideration of Economy, although I had written a paper on the subject as early as 1878. But Mach goes altogether too far. For he allows thought no other value than that of economizing experiences. This cannot for an instant be admitted. Sensation, to my thinking, has no value whatever except as a vehicle of thought.

But Proposals for hypotheses inundate us in an overwhelming flood, while the process of verification to which each one must be subjected before it can count as at all an item even of likely knowledge is so very costly

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in time, energy, and money,— and consequently in ideas which might have been had for that time, energy, and money, that Economy here would override every other consideration even if there were any other serious considerations. In fact there are no others. For abduction commits us to nothing. It merely causes a hypothesis to be set down upon our docket of cases to be tried.

I shall be asked, Do you really mean to say that we ought not to adopt any opinion whatever as an opinion until it has sustained the ordeal of furnishing a prediction that has been verified?