Wednesday, January 30, 2019

Justification and units of assertion

It’s clear to me that each of two assertions could individually meet the evidential bar for assertibility, but that their conjunction, being typically less probable than either conjucnt, might not. But then there is something very strange about the idea that one could justifiably assert “S1. S2.” but not “S1 and S2.” After all, is there really a difference in what one is saying when one inserts a period and when one inserts an “and”?

Perhaps the thing to say is that the units of assertion are in practice not single sentences, but larger units. How large? Well, not whole books. Plainly, as the preface paradox notes, one can be justified in producing a book while thinking there is an error somewhere in it (as long as one does not know where the error lies). I think not whole articles, either. Again, we expect to be mistaken somewhere in a complex article. Perhaps the unit of assertion is something more of the order of a paragraph or less, but more than a sentence.

If so, then in typical cases “S1. S2.” will be a single unit of assertion, and to be justified in asserting the unit, one needs to be justified in the conjunction. This gives us a pretty precise definition of a unit of assertion: a unit of assertion is an assertoric locution that is lengthwise maximal with respect to needing to be justified.

What in practice determines the unit of assertion is probably determined by a mix of content, context, intonation, length of pauses, etc. For instance, a topic switch is apt to end a unit of assertion, and it may sometimes make a difference how long the pause between the sentences in “S1. S2.” with respect to whether the sentences form a single unit of assertion.

Surely people have written on this.

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