In Kant's famous division between a priori vs a postriori, and synthetic vs analytic, Kant's example for a priori analytic proposition is:

All bodies are extended.

Without immediately delving into the proposition itself, I'd like to ask why (if at all) Kant considers extendedness to be an a priori trait. I'll give a bit more context-

In later chapters Kant discuss one of the only a priori metaphysical objects (or subject?) - space (spatiality? Not sure about the proper English term). The proposition is quite simple: in order to think of anything we'd first need to contain it inside something, no matter if it's a thought or "physical" object (not sure if Kant would agree exactly to that sentencing, as it's more of a Spinozanian metaphysical space) - we always "imagine" it contained within some container, and even if we try to "get out" of that container -- we're simply ending up in a bigger container.

After taking space as an a priori metaphysical object, we need to discuss if extendedness (the ontology of physique, or "being in space") is also a priori metaphysical or a postriori (or maybe more precisely, analytic a priori or synthetic a priori). If we go to the direction that says extendedness is analytic a priori, I think it takes us more to a Leibnizian metaphysics rather than Kantian, so I'd have to assume Kant take extendedness to be synthetic a priori. But if extendedness is synthetic a priori, what does it mean to the quote above, as Kant gives it as analytic a priori? Or maybe the judgment itself on the link between body and extendedness is analytic a priori, but extendedness itself is really synthetic a priori?

I hope this isn't too convoluted.

  • Bodies are extended by definition - hence its analytic. Where does Kant actually say this proposition is a priori? Jul 8, 2018 at 11:44
  • @MoziburUllah correct, Kant doesn't specify the proposition by its a priori-ty, only by its analyticity. But when Kant define the 4 possible combinations of analytic-synthetic and a priori-a postriori, it's quite obvious that the proposition falls under "analytic a priori". Jul 8, 2018 at 15:54
  • 1
    Kant isn’t saying that ‘body’ or ‘extended’ is an a priori representation, he’s saying that the proposition ‘all bodies are extended’ is true by definition, i.e. independently of experience. The empty example here is ‘A is A.’ Subject A already contains predicate A, hence is true by definition, independent of confirmation or confutation by experience. The representation ‘body’ comes from experience, but the analytic proposition involved simply draws out what is implicit in the representation in accordance with the principle of contradiction. Because we cannot conceive of an unextended body. Jul 8, 2018 at 16:10
  • 1
    @WolandBarthes agreed until the last couple lines. And this is where I'm not sure about my wordings and I get a bit convoluted. If Kant considers "space" to be metaphysically a priori, is "extendedness" a synthetic or analytic a priori (or even a postriori?) term in relation to "space"? Jul 8, 2018 at 16:13
  • 1
    In what way do space and extendedness relate? Space is an a priori presentation, that is, a pure form of intuition. The application of space as an a priori presentation is a precondition for our perception of objects at all: objects appear in time and space. We recognize an object as extended definitionally, because we can perceive objects—and we are able to perceive objects in the first place only because we structure them in space-time as a condition of perception. This is my understanding, at least: we are in very difficult territory now. Jul 8, 2018 at 17:07


You must log in to answer this question.

Browse other questions tagged .