Physiological Idealism

An idealistic trend of thought in the development of physiology that emerged in the mid-19th century. At that time, when some physiologists studied the structure and function of the senses, they were unable to give a correct philosophical explanation for some major scientific findings, which often led to a transcendental idealism similar to that of Kant. This school of idealism in physiology was called "physiological idealism". German physiologist J.P. Müller (1801-1858) was its typical representative.

Although Müller's achievements in the study of the physiology of the senses were great, his explanation of these scientific findings was idealistic. According to Müller, what we know is only our sensations, not the objective things themselves. This in essence denies that cognition is a reflection of objective things.

In Müller's explanation, first of all, the external causes that produce sensations are confused and equated with the abnormal state of the sensory organs themselves. He holds that the sensations produced by the human sensory organs can be produced by external causes or not. This means that sensations can also be produced by causes internal to the senses. For example, in the case of the sensation of light, he said, "however we strongly press upon the eye in the dark, so as to give rise to the appearance of luminous flashes, these flashes, being merely sensations, are incapable of illuminating external objects.” According to him, all the reflections of the optic sensory organs produced by the stimulation of external objects can be caused by the internal stimulation of our nerves.

Müller also held that stimuli produced by external causes can cause a corresponding change in the internal state of the sensory organs, and that the sensory organs produce sensations through this corresponding change. For example, for the sensation of light, Müller lists five external stimuli that can produce the sensation of light. They are special fluctuations and emissions (such as visible light), mechanical stimuli (such as concussion, blow, etc.), electricity, chemical agents (such as narcotics), and the stimulus of the blood. So the senses do not transmit to the consciousness the nature and state of external things, but the corresponding changes and states of the sensory nerves excited by external causes. This means that we feel only the corresponding changes in our senses, not the external thing itself. From this he concludes that it is impossible for our senses to reveal to us the truth and nature of the material world. What we know when we interact with nature outside our bodies is always only our own senses. Thus, in essence, we deny that our cognition is a reflection of the objective reality. So Lenin criticized that “the idealism of this physiologist consisted in the fact that when investigating the significance of the mechanism of our sense-organs in relation to sensations, showing, for instance, that the sensation of light is produced as the result of the action of various stimuli on the eye, he was inclined to arrive from this at a denial that our sensations are images of objective reality." Lenin considered both physical idealism and physiological idealism as "a temporary deflection" in the history of scientific development, as "a transitory period of sickness", as "an ailment of growth".