A proposition is analytic if the content of the predicate-concept of the proposition is already contained within the subject-concept of that proposition. Kant further elaborates on the distinction between "analytic" and "synthetic" judgments. Knowledge gained a posteriori through the senses, Kant argues, never imparts absolute necessity and universality, because it is always possible that we might encounter an exception. A proposition is universal if it is true in all cases, and so does not admit of any exceptions. A proposition is necessary if it could not possibly be false, and so cannot be denied without contradiction. This grants the possibility of a priori knowledge, since objects as appearance "must conform to our cognition.which is to establish something about objects before they are given to us." Knowledge independent of experience Kant calls " a priori" knowledge, while knowledge obtained through experience is termed " a posteriori." According to Kant, a proposition is a priori if it is necessary and universal. Kant regards the former "as mere representations and not as things in themselves", and the latter as "only sensible forms of our intuition, but not determinations given for themselves or conditions of objects as things in themselves".
This is argued through the transcendental idealism of objects (as appearance) and their form of appearance.
He expounds new ideas on the nature of space and time, and tries to provide solutions to the skepticism of Hume regarding knowledge of the relation of cause and effect and that of René Descartes regarding knowledge of the external world. Kant builds on the work of empiricist philosophers such as John Locke and David Hume, as well as rationalist philosophers such as Gottfried Wilhelm Leibniz and Christian Wolff. In the preface to the first edition, Kant explains that by a "critique of pure reason" he means a critique "of the faculty of reason in general, in respect of all knowledge after which it may strive independently of all experience" and that he aims to reach a decision about "the possibility or impossibility of metaphysics." Also referred to as Kant's "First Critique", it was followed by his Critique of Practical Reason (1788) and Critique of Judgment (1790). Critique of Pure Reason ( German: Kritik der reinen Vernunft 1781 second edition 1787) is a book by the German philosopher Immanuel Kant, in which the author seeks to determine the limits and scope of metaphysics.