From this quote, it's clear the ground of our representations, all of phenomena, can't be an object of phenomena. It must be an object in the realm of noumena & it must exist in order for empirical realism to be true. — Sirius

Further, we are now also able to determine our concepts of an object in general more correctly. All representations, as representations, have their object, and can themselves be objects of other representations in turn. Appearances are the only objects that can be given to us immediately, and that in them which is immediately related to the object is called intuition. However, these appearances are not things in themselves, but themselves only representations, which in turn have their object, which therefore cannot be further intuited by us, and that may therefore be called the non-empirical, i.e., transcendental object = X.
The pure concept of this transcendental object (which in all of our cognitions is really always one and the same = X) is that which in all of our empirical concepts in general can provide relation to an object, i.e., objective reality. Now this concept cannot contain any determinate intuition at all, and therefore concerns nothing but that unity which must be encountered in a manifold of cognition insofar as it stands in relation to an object. This relation, however, is nothing other than the necessary unity of consciousness, thus also of the synthesis of the manifold through a common function of the mind for combining it in one representation. — Critique of Pure Reason, A109

All our representations are in fact related to some object through the understanding, and, since appearances are nothing but representations, the understanding thus relates them to a something, as the object of sensible intuition: but this something a is to that extent only the transcendental object. This signifies, however a something = X, of which we know nothing at all nor can know anything in general (in accordance with the current constitution of our understanding), but is rather something that can serve only as a correlate of the unity of apperception for the unity of the manifold in sensible intuition, by means of which the understanding unifies that in the concept of an object. This transcendental object cannot even be separated from the sensible data, for then nothing would remain through which it would be thought. It is therefore no object of cognition in itself, but only the representation of appearances under the concept of an object in general, which is determinable through the manifold of those appearances, Just for this reason, then, the categories do not represent any special object given to the understanding alone, but rather serve only to determine the transcendental object (the concept of something in general) through that which is given in sensibility, in order thereby to cognize appearances empirically under concepts of objects. — ibid. A250/B305

The object to which I relate appearance in general is the transcendental object, i.e., the entirely undetermined thought of something in general. This cannot be called the noumenon, for I do not know anything about what it is in itself, and have no concept of it except merely that of the object of a sensible intuition in general, which is therefore the same for all appearances. I cannot think it through any categories; for these hold of empirical intuition, in order to bring it under a concept of the object in general. To be sure, a pure use of the category is possible/ i.e., without contradiction, but it has no objective validity, since it pertains to no intuition that would thereby acquire unity of the object for the category is a mere function of thinking, through which no object is given to me, but rather only that through which what may be given in intuition is thought. — ibid. A253/B308

What do you think Descartes’ solipsism problem was? — Mww

From all this one sees that rational psychology has its origin in a mere misunderstanding. The unity of consciousness, which grounds the categories, is here taken for an intuition of the subject as an object, and the category of substance is applied to it. But this unity is only the unity of thinking, through which no object is given; and thus the category of substance, which always presupposes a given intuition, cannot be applied to it, and hence this subject cannot be cognized at all. — ibid. B420

Well, it would be quite misguided to think that one gains insight into what the word 'thehousenextdoor' means by reading the original work that gave the world the word, for then one would believe it is exclusively about what a particular house is made of, plus about its appearance. — Clarendon

The only thing I can really call a supplement, and that only in the way of proof, is what I have said at B 273 in the form of a new refutation of psychological idealism, and a strict proof (the only possible one, I believe) of the objective reality of outer intuition. No matter how innocent idealism may be held to be as regards the essential ends of metaphysics (though in fact it is not so innocent), it always remains a scandal of philosophy and universal human reason that the existence of things outside us (from which we after all get the whole matter for our cognitions, even for our inner sense) should have to be assumed merely on faith, and that if it occurs to anyone to doubt it, we should be unable to answer him with a satisfactory proof. — C Pure R, Preface B XXXIX

The proof that is demanded must therefore establish that we have experience and not merely imagination of outer things, which cannot be accomplished unless one can prove that even our inner experience, undoubted by Descartes, is possible only under the presupposition of outer experience. — ibid. B275

You, on the other hand, take a bit of text and use it as the basis for what ends up being self reflection. You want every philosopher to be something like a materialist, and you take one word and draw out a materialist outlook. — frank

I have a much broader outlook. — frank

The mere, but empirically determined, consciousness of my own
existence proves the existence of objects in space outside me. — Critique of Pure Reason, B275

He's just saying that consciousness of my own existence requires something to compare and contrast with me. The use of dialectics runs through the CPR. This is a case of that. — frank

Even if I had a very intimate discussions on many topics or shared some daily life experience with someone, I would not claim I know their deep true inside feelings, thoughts and wills. — Corvus

Per Kant, we don't learn about space and time a posteriori. — frank

He's just saying that consciousness of my own existence requires something to compare and contrast with me. The use of dialectics runs through the CPR. This is a case of that. — frank

The mere, but empirically determined, consciousness of my own
existence proves the existence of objects in space outside me. — Critique of Pure Reason, B275

Now this is not a solipsism like some have been misled on the point. — Corvus

From what I've seen the main argument in the last two pages has been that Banno thinks if there are things we don't currently know, then Antirealism can't hold. — AmadeusD

I'm not all that concerned about it, I guess, otherwise I would have been doing that all along. — Janus