Having read Kant's Critique of Pure Reason, and in fact just finishing a second read after some time, I've been trying to develop a suitable "worldview" about the structure of the mind.

I believe I am something of a subjective idealist when it comes to the world generally, and this is due to my inability to fully disconnect empirical from a priori experiences.

But am justified in that?

From various sources (Husserl, Levinas, etc) we find that "consciousness is consciousness of something". So, when it comes to a priori thinking (intuitions, knowledge, etc), I fail to understand how such an entity can be fully "pure". (Reflecting, I daresay Kant himself does not mention pure a prior entities).

I see it as this: A priori and a posteriori entities exist as 'gradations' against each other, wherein an empirical object can never truly be distinct from a mind, and likewise an a prior intuition (say) can never truly be distinct from a body.

Having said that, I think I can grasp a little of Transcendental Idealism, in the sense in which objects can exist within themselves, albeit distinct from experience (do I have that right?).

In short, the question is as the heading.

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    Brentano's thesis that consciousness is intentional ("of something") is accepted by the phenomenological tradition, but controversial. Anti-intentionalists contend that there are "phenomenal" mental states that are not intentional, even derivatively, see SEP. The problem with "pure a priori thinking" lies elsewhere, all proposed candidates for it were shown to surreptitiously mix in some very a posteriori (and oft mistaken) input.
    – Conifold
    Commented Aug 23, 2023 at 3:13
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    See D'Agostini, sec.5 for an interesting historical perspective on phenomenological tradition:"The wide interest in the nature of pure thought and pure theory... was partially connected to the effort made by philosophy to save its own primacy and identity... However, it was not on behalf of pure thought that the battle was won. On the contrary, the very adjective ‘pure’ soon began to fade, and the research culminated (for Heidegger since the 1923 winter courses on Faktizität) with the victory of impure existential thought."
    – Conifold
    Commented Aug 23, 2023 at 3:19
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    Or the modern neuroscientist perspective vis-a-vis Dean Buonomano, “the first thing the brain knows is the body”
    – J Kusin
    Commented Aug 23, 2023 at 4:35
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    Since you've read CPR twice you must already intuitively believe or tend to believe pure a priori thinking from somewhere contingently. Re your "an a prior intuition (say) can never truly be distinct from a body", Kant stressed pure intuition has to ground to sensibility from a body not unlike contemporary embodied cognition principle, so in this sense they never be truly distinct though utterly heterogeneous. But for your "an empirical object can never truly be distinct from a mind", Kant's thing-in-itself object surely exists but can be truly distinct and inscrutable from an arbitrary mind.. Commented Aug 23, 2023 at 6:03
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    Being conscious of thought is within pure reason, is it not? Commented Aug 23, 2023 at 6:15

2 Answers 2


Kant says that we cannot even think purely without being given an intuition. If we're speaking of a priori pure thought, this intuition is the pure intuition of time or space (cf. B161 for distinction between pure/formal intuitions and forms of intuition). We find an example of how to do that in the Analytic of Principles, especially in the Schematism chapter, where pure logical categories are applied to the pure intuitions of time producing pure time-determinations. Later, the whole of Transcendental Dialectic is a demonstration that thought cannot produce its own content, i.e. that it constitutes mere combination of already given content, which is spatio-temporal not due to nature of thinking itself, but due to contingent matters regarding the form of our sensibility. Therefore, there cannot be pure a priori thought without something given from sensibility, albeit neverthless purely, because the given is the form of sensibility.

I assume your confusion is due to the assumption that pure a priori thought would involve nothing but logical categories. But Kant insists that it is only in applying those categories to the formal intuitions of time and space that any knowledge can be acquired, in contrast with the later German Idealists, beggining already with Fichte.


I believe this answer will depend on how broad the definition of thought is.

The brain sends signals to the heart to keep it beating and lungs to enable breathing. If these qualifify as thoughts then they could be considered candidates for pure apriori thought. These occur in the earliest stages of development and start without the benefit of experience or even consciousness.

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