Assertion and the Force–Content Distinction

Описание: The force-content distinction is one of the most important ideas in logic. Compare the following two sentences:

"You are in France"
"You are in France...IF you're in Paris"

The second is true, no matter what; the first is not. Yet "You are in France" has the same meaning in both instances, both as a stand-alone sentence and as the antecedent of a conditional: it has, as we say, the same *content*. The difference is, the first claims (asserts) that you are in France, whereas the second one makes no such claim. Thus the first attaches assertive force to the sentence "You are in France".

Distinguishing the meaning/content from the force of a sentence was one of the proudest accomplishments of the greatest logician of the modern age, Gottlob Frege (1848-1925).

How many kinds of force are there? The Fregeans commonly recognize three: assertion, interrogative force (asking a question—"are you in France?") and imperative force ("Go be in France!").

Now this distinction in terms of what we do in speech has a parallel distinction on the level of mind: assertion is an outward display of mental JUDGMENT, whereas non-assertive sentences are outward displays of acts of ENTERTAINMENT. (Entertainment is what I am doing when I ask myself, for example, "What would it be like if I were in France?").

Now here is a question: is entertainment prior to judgment, or is judgment prior to entertainment? Do we first think about what it would be like to be in Paris, and then judge it to be true? Or do we have the thought of being in Paris, then remove the judgment (that it is true) from the thought?

Frege seems to think of judgment/assertion as something added on to an entertained thought. But Gilbert Ryle (1900-1976) argues in "The Concept of Mind" (1949) that actually, entertainment is a more complicated mental operation than mere judgment. More recently, Peter Hanks has argued, in "Propositional Content" (2015) that assertion is basic, and assertive force is cancelled in specific contexts—conditional sentences, assumptions in indirect proof, and so forth.

For my part, I like to think of these views in terms of switches: Frege's view treats assertion like a toggle switch: it is just as well on as it is off. Hanks's view treats assertion like a kill switch: on, unless—in certain circumstances—it is shut off.

Now even though Frege considered this one of his own most important discoveries, the central insight is actually much older: it's present in Avicenna (980-1037), Abelard (1079-1142), and Buridan (1300-1360). But Abelard, for instance, recognized more kinds of "force" than contemporary Fregeans do: he also recognized optatives ("If only I were in Paris") and vocatives, ("Hey you in Paris!"), in addition to assertion, interrogatives, and imperatives.

So this is just one of those perennial problems in logic, which will keep coming up again and again.

CHAPTERS
00:00 Frege on force-content
00:16 How the force-content distinction works
1:02 Imperative and interrogative force
1:37 The assertion sign ('⊢')
2:04 Judgment vs. entertainment
2:35 Gilbert Ryle and Peter Hanks
3:45 Avicenna, Abelard, and Buridan

Special thanks to Patrick Robert Coppola for his help with the camera work!

This video is brought to you by the FWO, as a part of a project on indirect proof and assertion. You can see a brief overview of the project here: https://research.kuleuven.be/portal/e...

For information about the FWO, see: https://www.fwo.be/en/
For information about the FWO's junior postdoc (the one that I hold), see: https://www.fwo.be/en/support-program...

Photo credits:
Photo of Paris:
LagrangeHervé (https://pixabay.com/photos/city-urban...)
Kill switch: planet_fox (https://pixabay.com/photos/heating-em...)
Toggle switch: PublicDomainPictures (https://pixabay.com/photos/switch-pan...)
Peter Abelard (unaltered, original, under a Creative Commons 3.0 license): Jastrow
(link: https://commons.wikimedia.org/wiki/Fi...)