Not only in judgements, however, but even in conceptions, is an a priori origin manifest. For example, if we take away by degrees from our conceptions of a body all that can be referred to mere sensuous experience — colour, hardness or softness, weight, even impenetrability — the body will then vanish; but the space which it occupied still remains, and this it is utterly impossible to annihilate in thought. Again, if we take away, in like manner, from our empirical conception of any object, corporeal or incorporeal, all properties which mere experience has taught us to connect with it, still we cannot think away those through which we cogitate it as substance, or adhering to substance, al: that though our conception of substance is more determined than that of an object. Compelled, therefore, by that necessity with which the conception of substance forces itself upon us, we must confess that it has its seat in our faculty of cognition a priori.

Kant's Preface to the Critique of Pure Reason.

He seems to be saying that our empirical conception of a visual sense object necessarily takes up some space: that we can only see things that take up space.

And when Wittgenstein says that:

our visual field has no limits

that we cannot represent the horizon of what we see, is he talking about the same phenomena?

If the limits of the visual field cannot be defined then must it always have the same extent? Is it impossible to "annihilate in thought" our visual field - because it has no limits?

  • I just ask cos I'm fascinated by questions like that.
    – user6917
    Commented Aug 15, 2014 at 18:46

1 Answer 1


For Kant, we can only see objects that take up space because space is an a priori condition of all human experience of the external world[1]. For Kant, space does not exist independently of human experience. We might say space is the medium of our experience of the external world. Experience of the external world without space is as sound in a vacuum, for Kant it doesn't exist.

Kant's point is metaphysical (and perhaps psychological).

Wittgenstein's point is about language. Pictures have borders, we are only confusing ourselves and perhaps others if we talk about the part of a picture that isn't on the canvas.

[1] For Kant, time is the a priori condition of all inner experience.

  • I think this is a great answer overall so +1. My only comment would be that it's an open question among Kant scholars whether Kant's view entails the denial of mind-independent space. I believe the dominant opinion called the epistemic interpretation is that it does not but our mode of knowing makes it so that what we call "space" is an a priori pre-condition of our cognition and knowledge. The opposite (minority) view is the metaphysical interpretation which entails Kant believe space is only the cognitive a priori tool.
    – virmaior
    Commented Aug 18, 2014 at 8:14
  • @virmaior Well someone will always be inclined to claim space as a din an sich in order to support claims that scientific enquiries can return results independent of human psychology. The further Kant's days differ from our own the more attractive doing so becomes and the less friction it creates. Short of anachronism, it is hard to reconcile objective space with its synthetic a priori derivation or within the larger context of Kant's corpus as an investigation of moral knowledge. Commented Aug 18, 2014 at 13:06
  • What you're supposing is different than the epistemic interpretation. I'm not claiming (nor is anyone offering the epistemic interpretation) that anything humans do gets out of using time and space as the joint conditions of all of the objects of our experience -- nor am I claiming space is a ding-an-sich (note the g). The claim is not that there is objective space but that Kant is not talking about "objective space" (by which I assume you mean unconditioned real space -- since objective Gegenstandlich or Objektiv refers to that which is rendered under the categories for Kant).
    – virmaior
    Commented Aug 18, 2014 at 13:19
  • For a brief list of major Kant scholars who use the epistemic interpretation, here's Henry Allison [ndpr.nd.edu/news/…, Karl Amerkis [ndpr.nd.edu/news/23771-interpreting-kant-s-critiques/], Michael Rolf's SEP article [plato.stanford.edu/entries/kant/] and Theodore Plantinga [calvin.edu/academic/philosophy/virtual_library/articles/….
    – virmaior
    Commented Aug 18, 2014 at 13:21
  • Btw, moral knowledge in Kant was actually the topic of my doctoral dissertation... The need for a epistemological interpretation has more to do with what's happened after Kant than Kant himself who leaves several of his largest problems as exercises for the reader.
    – virmaior
    Commented Aug 18, 2014 at 13:22

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