Things-in-them-selves...

Things-in-them-selves, which are the causes of sensations, are unknowable; they are not in space or time, nor are they substances. In addition to the subjectivity of space and time, Kant believes in the subjectivity of these twelve categories divided into four sets of three: (1) of quantity.

unity, plurality, totality, (2) of quality: reality, negation, limitation, (3) of relation: substance-and-accident, cause-and-effect, reciprocity, (4) of modality: possibility, existence, necessity (of these, al-Sadr mentions only causality). These, like time and space, are subjective. i.e. our mental constitution is such that they are applicable to whatever we experience, but there is no reason to suppose them applicable to things-in-themselves. Mathematical propositions are all a priori.

These are the only synthetic judgements which are a priori, because they rest not upon the variable and contingent content of experience but upon the unchanging forms of space and time in which all experience is given. The statements of natural science, which are empirical and synthetic, are composed of two elements, one of which is empirical and the other rational.

The empirical aspect relates to the content or stuff of experience, whereas the rational element relates to mind and its forms and categories. The natural sciences, according to Kant, do not describe the external order of things-in-themselves, but are valid and trustworthy within the realm of experience, i.e. the experienced order of 'things-in-us'.

Here al-Sadr does not appear to appreciate the depth of Kant's skepticism regarding the knowledge of the external world, which he interprets as a kind of relativism.

Hence these statements of his: "Knowledge (in Kant's philosophy), therefore, is a mixture of subjectivity and objectivity", and "That is why relativity is imposed on every truth representing external things in our knowledge, in the sense that our knowledge indicates to us the thing's reality in us, and not the thing's reality in itself".

He does not seem to notice that Kant's extreme subjectivism makes not only metaphysics impossible but so also natural science, which is reduced to some kind of phenomenology. Kant's subjectivism makes his realism altogether ineffectual. The things-in-themselves are shadows that lurk on the boundaries of his system, which is idealist and subjective through and through. His realism is as useless for science as his rationalism is useless for metaphysics and theology.