Sense Experience and the Thing-in-itself

Al-Sadr here quotes Marxist texts that state that there is no basic

difference between the thing-in-itself and the phenomenon, between outward reality and the manner in which it appears to consciousness. But there is a duality here, between appearance and reality, for according to empiricism the senses perceive only the phenomena. Can Marxism eliminate this duality and prove that external reality appears to us in our percept s and ideas as it is?

The answer is, No, because knowledge according to materialism is purely a physiological act. Unlike mechanical materialists, the dialectical materialists claim that the idea of a thing is not its pure mechanical picture. Since qualitatively different forms of motion can transform from one to another, the physical motion of a thing changes into a physiological motion in our senses. Then the physiological motion changes into the psychological motion of the idea. To begin with such changes are not admissible, and even if they be admitted it means that Marxism does not succeed in revealing the relation between a thing and its idea except as a relation between a cause and its effect or at the most that of a reality and its reflected picture.

But why should we assume that this effect and cause differ from other effects and causes and are distinguished from them by a special characteristic, namely that the effect pictures its cause faithfully? Of course, there are many physiological events that are effects of external causes without having the capacity of picturing their causes. Even if such a thing were admitted, how do we know that the idea (percept) fully corresponds to the objective reality?

The Marxists answer this objection by asserting that thought is a part and product of nature; rather its highest expression. Our knowledge is nothing other than a superior product of nature; it cannot but reflect the laws of the motions of matter. The products of thought, being the products of nature, are not in contradiction but in agreement with the rest of material nature.

Yet this is not sufficient for proving the possibility of knowledge. Aren't idealist thought and theological and metaphysical thought as much part of nature and products of it as dialectical materialism?