argument Status: checked Produced by claude-fable-5-1, 2026-10-06 Verified by nobody yet

We must be able to think the same objects as things in themselves, or there would be appearance without anything that appears

If we could not think the objects given to us as appearances also as things in themselves, there would be appearance without anything that appears; that is absurd; so we must at least be able to think them as things in themselves.

The argument

Form

w there is no appearance without something that appears
t we must at least be able to think the same objects also as things in themselves

P1w
P2(¬t → ¬w)
Ct

Machine check, truth table: valid: the conclusion holds in all 1 assignments of t, w that satisfy the premises. The check says nothing about whether the premises are true or faithful to the passage; only a named human can (DISPUTES.md).

The argument is two sentences at B xxvi–xxvii: it is "always reserved that we must at least be able to think, even if we cannot cognize, these same objects also as things in themselves. For otherwise the absurd proposition would follow that there is appearance without anything that appears" (AA 3:17.02–07). The second sentence is the conditional (premise 2); that its consequent is absurd gives premise 1; the conclusion follows by modus tollens. The context, that we cognize objects only as appearances (AA 3:16.34–36), is what "these same objects" refers to and is not a premise of the step.

What is unstated is why denying the reservation would leave appearance without anything that appears; the text asserts the conditional and does not argue it. Prolegomena §32 states a stronger form of the inference: by admitting appearances the understanding admits the existence of things in themselves, and the representation of such beings is unavoidable (AA 4:315.02–06). The form's conclusion is the "must be able to think"; the concessive "even if we cannot cognize" (AA 3:17.04) is carried by the separate claim that we cognize objects only as appearances.

Depends on

c-kant-appearance-presupposes-something-appearingAn appearance presupposes something that appears
c-kant-without-things-in-themselves-appearance-without-appearingIf the same objects could not be thought as things in themselves, there would be appearance without anything that appears

Supports

c-kant-things-in-themselves-thinkable-not-knowableThe same objects must be thinkable, though not knowable, as things in themselves

Permanent address: /a/kant-appearance-requires-thing-in-itself/ · Produced by claude-fable-5-1, 2026-10-06 · Disputes: none

Kritik der reinen Vernunft B xxvi–xxvii (AA 3:16.30–17.07)korpora.org, AA III 16–17

Daß Raum und Zeit nur Formen der sinnlichen Anschauung, also nur Bedingungen der Existenz der Dinge als Erscheinungen sind, daß wir ferner keine Verstandesbegriffe, mithin auch gar keine Elemente zur Erkenntniß der Dinge haben, als so fern diesen Begriffen correspondirende Anschauung gegeben werden kann, folglich wir von keinem Gegenstande als Dinge an sich selbst, sondern nur so fern es Object der sinnlichen Anschauung ist, d. i. als Erscheinung, Erkenntniß haben können, wird im analytischen Theile der Kritik bewiesen; woraus denn freilich die Einschränkung aller nur möglichen speculativen Erkenntniß der Vernunft auf bloße Gegenstände der Erfahrung folgt. Gleichwohl wird, welches wohl gemerkt werden muß, doch dabei immer vorbehalten, daß wir eben dieselben Gegenstände auch als Dinge an sich selbst, wenn gleich nicht erkennen, doch wenigstens müssen denken können. Denn sonst würde der ungereimte Satz daraus folgen, daß Erscheinung ohne etwas wäre, was da erscheint.

That space and time are only forms of sensible intuition, hence only conditions of the existence of things as appearances; that further we have no concepts of the understanding, and so no elements at all for the cognition of things, except insofar as intuition corresponding to these concepts can be given; and consequently that we can have cognition of no object as a thing in itself, but only insofar as it is an object of sensible intuition, that is, as appearance: this is proved in the analytical part of the Critique. From this there follows, to be sure, the restriction of all possible speculative cognition of reason to mere objects of experience. Nevertheless, and this must be well noted, it is always reserved that we must at least be able to think, even if we cannot cognize, these same objects also as things in themselves. For otherwise the absurd proposition would follow that there is appearance without anything that appears. — the project

Prolegomena zu einer jeden künftigen Metaphysik, die als Wissenschaft wird auftreten können §32 (AA 4:314.33–315.06)korpora.org, AA IV 314–315

In der That, wenn wir die Gegenstände der Sinne wie billig als bloße Erscheinungen ansehen, so gestehen wir hiedurch doch zugleich, daß ihnen ein Ding an sich selbst zum Grunde liege, ob wir dasselbe gleich nicht, wie es an sich beschaffen sei, sondern nur seine Erscheinung, d. i. die Art, wie unsre Sinnen von diesem unbekannten Etwas afficirt werden, kennen. Der Verstand also, eben dadurch daß er Erscheinungen annimmt, gesteht auch das Dasein von Dingen an sich selbst zu, und so fern können wir sagen, daß die Vorstellung solcher Wesen, die den Erscheinungen zum Grunde liegen, mithin bloßer Verstandeswesen nicht allein zulässig, sondern auch unvermeidlich sei.

Indeed, if we regard the objects of the senses, as is proper, as mere appearances, we thereby at the same time grant that a thing in itself underlies them, even though we do not know it as it is constituted in itself but only its appearance, that is, the way our senses are affected by this unknown something. The understanding, then, precisely by admitting appearances, also admits the existence of things in themselves, and to that extent we can say that the representation of such beings as underlie the appearances, hence of mere beings of the understanding, is not only admissible but also unavoidable. — the project

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