The Commens Dictionary

Quote from ‘Reason's Rules’


…it does not follow that because every theoretical belief is, at least indirectly, a practical belief, this is the whole meaning of the theoretical belief. Of theoretical beliefs, in so far as they are not practical, we may distinguish between those which are expectations, and those which are not even that. [—]

…there is just this difference between a practical belief and an expectation so far as it involves no purpose [or] effort; namely that the former is expectant of muscular sensation, the latter of sensation not muscular. The expectancy consists in the stamp of approval, the act of recognition as one’s own, being placed by a deed of the soul upon an imaginary anticipation of experience; so that, if it be fulfilled, though the actual experience will, at all events, contain enough of the unexpected to be recognized as external, yet the person who stands in expectancy will almost claim the event as his due, his triumphant “I told you so” implying a right to expect as much from a justly-regulated world. A man who goes among a barbarous tribe and announces a total eclipse of the sun next day, will expect, not only “his” eclipse from Nature, but due credit for it from that People. In all this, I am endeavoring so to shape what I have to say as to exhibit, besides, the close alliance, the family identity, of the ideas of externality and unexpectedness.

As to purely theoretical beliefs not expectacious, if they are to mean anything, they must be somehow expectative. The word “expect” is now and then applied by careless and ignorant speakers, especially the English, to what is surmised in regard to the past. It is not illogical language: it is only elliptical. “I expect that Adam must have felt a little sore over the extraction of his rib,” may be interpreted as meaning that the expectation is, that so it will be found when the secrets of all hearts are laid bare. History would not have the character of a true science if it were not permissible to hope that further evidences may be forthcoming in the future by which the hypotheses of the critics may be tested. A theory which should be capable of being absolutely demonstrated in its entirety by future events, would be no scientific theory but a mere piece of fortune telling. On the other hand, a theory, which goes beyond what may be verified to any degree of approximation by future discoveries is, in so far, metaphysical gabble. To say that a quadratic equation which has no real root has two different imaginary roots does not sound as if it could have any relation to experience. Yet it is strictly expectative. It states what would be expectable if we had to deal with quantities expressing the relations between objects, related to one another like the points of the plane of imaginary quantity.

1902-03 [c.]
CP 5.539-41
‘Theoretical Belief’ (pub. 25.10.15-12:21). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from
Oct 25, 2015, 12:21 by Mats Bergman
Last revised: 
Oct 25, 2015, 12:23 by Mats Bergman