PROBLEM IV.
THE REFLEX THEORY.
“Si omnes patres sic, et Ego non sic.”—Abelard, Sic et Non.
“Will man bestimmen wo der Mechanismus aufhört und wo der Wille anfängt so ist die Frage überhaupt falsch gestellt. Denn man setzt hier Begriffe einander gegenüber die gar keine Gegensätze sind. Vorgebildet in den mechanischen Bedingungen des Nervensystems sind alle Bewegungen.”—Wundt, Physiologische Psychologie.
“Sollte die so durchsichtige Homologie zwischen Hirn and Rückenmark, wie solche sich schlagend in Bau und Entwicklung darthut, wesentlich andere physiologische Qualitäten bedingen?”—Luschinger in Pflüger’s Archiv, Bd. XIV. 384.
THE REFLEX THEORY.
CHAPTER I.
THE PROBLEM STATED.
1. The peculiarity of the Reflex Theory is its exclusion of Sensibility from the actions classed as reflex; in consequence of which, the actions are considered to be “purely mechanical.”
No one denies that most of the reflex actions often have conscious sensations preceding and accompanying them, but these are said not to be essential to the performance of the actions, because they may be absent and the actions still take place. It is notorious that we breathe, wink, swallow, etc., whether we are conscious of these actions or not. Our conclusion therefore is that these peculiar states of Consciousness are accessory, not essential to the performance of these actions. The fact is patent, the conclusion irresistible. But now consider the equivoque: because an action takes place without our being conscious of it, the action is said to have had no sensation determining it. This, which is a truism when we limit Consciousness to one of the special modes Of Sensibility, or limit sensation to this limited Consciousness, is a falsism when we accept Consciousness as the total of all combined sensibilities, or Sensation as the reaction of the sensory mechanism. That a reflex action is determined by the sensory mechanism, no one disputes; whether the reaction of a sensory mechanism shall be called a sensation or not, is a question of terms. I have shown why it must be so called if anything like coherence is to be preserved in physiological investigations; and I have more than once suggested that the fact of intellectual processes taking place at times with no more consciousness than reflex actions, is itself sufficient to show that a process does not lapse from the mental to the mechanical sphere simply by passing unconsciously.
Inasmuch as an organism is a complex of organs, its total function must be a complex of particular functions, each of which may analytically be treated apart. Vitality is the total of all its physiological functions, and Consciousness the total of all its psychological functions. But inasmuch as it is only in its relation to the whole that each part has functional significance, and cannot therefore be isolated in reality, as it is in theory—cannot live by itself, act by itself, independently of the organism of which it is an organ, there is strict accuracy in saying that no particular sensation can exist without involving Consciousness; for this is only saying that no sensory organ can react without at the same time involving a reaction of the general sensorium. But since this general sensorium is simultaneously affected by various excitations each of which is a force, every sensation, perception, emotion, or volition is a resultant of the composition of these forces; and as there can be only one resultant at a time, to be replaced by another in swift succession, this one represents the state of Consciousness, and this state may or may not be felt under the peculiar mode named “Consciousness,” in its special meaning. In other words, the reaction of a sensory organ is always sentient, but not always consentient.
2. Let us illustrate this by the sensation of musical tone. When we hear a tone we are affected not only by the fundamental tone, representing the vibrations of the sounding body as a whole, but also by the harmonics or overtones, representing the vibrations of the several parts of that whole. It is these latter vibrations which give the tone its timbre, or peculiar quality; and as the harmonics are variable with the variable structure of the vibrating parts, two bodies which have the same fundamental tone may have markedly different qualities. There are some tones which are almost entirely free from harmonics; that is to say, their harmonics are too faint for our ear to appreciate them, though we know that the vibrations must be present. Apply this to the excitations of the sensorium. Each excitation will have its fundamental feeling, and more or less accompanying thrills of other feelings: it is these thrills which are the harmonics, giving to each excitation its specific quality; but they may be so faint that no specific quality is discriminated. A fly settles on your hand while you are writing, the faint thrill which accompanies this excitation of your sensory nerve gives the specific sensation of tickling, and this causes you to move your hand with a jerk. If your attention is preoccupied, you are said to be unconscious of the sensation, and the jerk of your hand is called a reflex action; but if your attention is not preoccupied, or if the thrill is vivid, you are said to be conscious of the sensation, and the action is no longer reflex, but volitional. Obviously here the difference depends not on the sentient excitation by an impression on the nerve, but on the state of the general sensorium and its consequent reaction. Had not the impression been carried to the sensorium, no movement would have followed the fly’s alighting on your hand, because no sensation (sensory reaction) would have been excited; the hypothesis of a purely mechanical reflex is quite inadmissible.