Human automaton (gears exposed)
A human automaton, with gears exposed, a human machine example. [4]
In science, human machine, which is nearly synonymous with the "human motor", refers to the consideration or modelling of a human as a machine, views about which vary per century, from the pressure-driven automatons of ancient Greece, to comparisons humans to neurological-like watermills in the 18th century, to the late 19th century views of treating works as machines and attempting to get optimal efficiency out of them, to the computerized terminator premises of the modern day. [1]

In 1637, French natural philosopher Rene Descartes introduced the dominant version of the animal machine hypothesis. Descartes, in his Meditations (1641), gave his view as follows: [6]

“The bird or dog which we imagine as it flies or runs, that its act is conducted by thinking, willing and so on, is not so actuated. Its movements are in truth just the running of a wound-up clock. So likewise with many of our motions, yours and mine. And as a clock composed of wheels and weights observes not less exactly all the laws of nature when it is ill-made and does not tell the house as well as when it is entirely to the wish of the workman, so in like manner I regard the human body as a machine so built and put together of bone, nerve, muscle, vein, blood and skin, that still, although it had no mind, it would not fail to move in all the same ways as at present, since it does not move by the direction of its will, nor consequently by means of the mind, but only by the arrangement of its organs.”

In his post-humorous Of Men (De Homine), Descartes gives his final views on the matter: [6]

“I repeat I want you to regard these functions as taking place naturally in this machine because of the very arrangements of its parts, neither more nor less than do the movements of a clock or other automaton from the weights and wheels, so that there is no need on their account to suppose in it any soul vegetative or sensitive or any principle of life than its blood.”

French inventor Jacques Vaucanson famously made a 1737 flute player automaton and in 1738 a tambourine player and digesting duck automaton.

In 1747, French physician-philosopher Julien la Mettrie, inspired by Vaucanson's automaton's wrote, in his The Human Machine, the following: [2]

“It thus appears that there is but one type in the universe, and that man is the most perfect example. He is to the ape, and to the most intelligent animals, as the planetary pendulum of Huygens is to a watch of Julien Leroy. More instruments, more wheels, and more springs were necessary.”

In the 1850s, German physicist Gustave Hirn conducted experiments where he treated or modeled the human as a machine and attempted calculation of the mechanical equivalent of heat of humans.

In 1950, American mathematician Norbert Wiener commented the following:

“Certain analogies of behavior are observed between the machine and the living organism, the problem as to whether the machine is alive or not is, for our purposes, semantic … if we use the word ‘life’ to cover all phenomena which locally swim upstream against the current of entropy, we are at liberty to do so; however, we shall then include many astronomical phenomena … it is my opinion, therefore, best to avoid all question-begging epithets such as ‘life’, ‘soul’, ‘vitalism’, and the like, and say merely that machines [and] human beings [are] pockets of decreasing entropy in a framework in which the large entropy tends to increase.”
Human machine (Descartes)
A diagram of French natural philosopher Rene Descartes' machine view of the human.

Here one can begin to see a glimpse of the thermodynamics-based human molecule point of view, aka human chemical thermodynamics, which would eventually supplant the human machine model, namely that once one, in the post-1990s years, during which time human mass composition data sets and tables began to become readily available, begins to dig into the query of applying entropy, enthalpy, and free energy analysis to human movement, the model of a human as a reactive chemical structure comes quickly to the fore.

In 1897, Russian physiologist Ivan Pavlov published his The Work of the Digestive Glands, and soon thereafter, circa 1901, developed his “conditional reflex” stimulus response bell-ringing / salivating theory of digestive behavior in dogs. In 1913, building on Pavlov’s model, American psychologist John Watson founded the so-called behaviorism school with the publication of his “Psychology as the Behaviorist Views It”, wherein he argued that there is no dividing line between man and brute, that behaviorist psychology can be viewed as an objective experimental branch of natural science wherein structure is explained in physico-chemical terms, whereby the theoretical goal is prediction and control of behavior, and in which generally he outlined a outlined a machine-like reflex-arc model of behavior:

“That the organism is a machine is taken for granted in our work. The only point we insist upon is that the machine be made not too simple to perform the multitudinous demands which the behaviorist must take upon it. There has been a strong tendency on the part of the biologists to assume that the mechanisms are exceedingly simple.”

This is what is sometimes called machine-like deterministic behavior, according to which the human is viewed as a machine, albeit one not too simple, wherein, in Watson's view, the "findings of psychology become functional correlates of structure and lend themselves to explanation in physicochemical terms." [5]

1. (a) Schilling, Charles W. (1965). The Human Machine: Biological Sciences for the Armed Services. Navel Institute.
(b) Tucker, Abraham. (1768). The Light of Nature Pursued, Volume 1 (pgs. 61-62). T. Jones.
2. (a) La Mettrie, Julien. (1749). L’Homme Machine. Publisher.
(b) Scott, George P. (1985). Atoms of the Living Flame: an Odyssey into Ethics and the Physical Chemistry of Free Will (pg. 67). University Press of America.
3. Wiener, Norber. (1950). The Human Uses of Human Beings: Cybernetics and Society (ch. II: Progress and Entropy, pgs. 28-47). Houghton Mifflin Co.
4. Hendrix, Jenny. (2012). “Among the Automata”, The Paris Review, May 22.
5. Scott, George P. (1985). Atoms of the Living Flame: an Odyssey into Ethics and the Physical Chemistry of Free Will (pg. 124-25). University Press of America.
6. Sherrington, Charles. (1940). Man on His Nature (pgs. 160). CUP Archive.

Further reading
● Marey, Etienne-Jules. (1873). La Machine Animale. Publisher
● Thurston, Robert H. (1894). The Animal as a Machine and Prime Motor: and the Laws of Energetics. John Wiley & Sons.
● Nisbet, John. (1899). The Human Machine: an inquiry into the diversity of human faculty in its bearings upon social life, religion, education, and politics. G. Richards.
● Amar, Jules, Butterworth, Elsie M., and Wright, George E. (1920). Human Motor: or the Scientific Foundations of Labor and Industury. (human thermodynamics, pg. 191). G. Routledge & Sons.
● Wiener, Norber. (1948). Cybernetics: or Control and Communication in the Animal and the Machine. MIT Press.
● Rabinbach, Anson. (1990). The Human Motor - Energy, Fatigue, and the Origins of Modernity. Berkeley: University of California Press.

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