MENTAL FURNITURE #3

Galileo

©1997 Dennis Leri

Moshe Feldenkrais said that if you want to understand human action shift your focus from knowing 'why' to knowing 'how'. That shift did not originate with Moshe but with Galileo Galilei (1564-1642). It is what differentiates the natural philosophy of the Ancients represented by Aristotle (394-322 B.C.) from the origins of modern science represented by Galileo. Galileo is granted the honor of being the first modern scientist. In a future article I will make the case for Moshe Feldenkrais being the last modern scientist.

Aristotle held views on many subjects from drama to mathematics to biology. His views on causality and motion will be mentioned here. Aristotle distinguished four types of causality: 1) material cause - the matter from which a thing is formed; 2) formal cause - the form to be realized; 3) efficient cause - that which actually causes the event, and; 4) final cause - the purpose to be realized. Aristotle used the example of a statue to illustrate his point: the block of marble from which it is to be hewn is the material cause; the form which is present in the sculptor's mind during the work is the formal cause; the sculptor himself, through the intermediary of his tools, in his chipping away at the stone is the efficient cause; the destination or purpose of the completed statue is the final cause.

The first three causes refer to the thing itself. The fourth cause, final cause, evidences the very existence of a thing as the realization of a purpose. For Aristotle every living and every inanimate thing has purpose. Explanations which traffic in a thing's purpose are called teleological. In Aristotle's view the natural place for things is at rest. All motion is either natural or violent. Natural motion describes an object's movements towards its future final resting place where it achieves its purpose. Violent motion results from external forces which push or pull an object. For Aristotle, the cause of all natural movement is the Prime Mover. The Prime Mover does not set all things in motion at the beginning of time but instead draws all things unto it at the end of time. Not external gravity, but rather the object's own innate tendency explains why an object falls to earth. Aristotle's world view is common-sensical and intuitive. It held sway for 2,000 years.

Galileo, in the process of inventing the mechanistic world view, ousted purpose, or teleology altogether from science. He narrowed his scope of concern to a description of how an object, any object, moves. He was not concerned with appearances but with relationships of number, time and space. The mechanistic world view, much derided nowadays, appeals to mathematics for the basis of its inquiry into the working of nature. Galileo considered nature, "...a giant open book written in the language of mathematics." Mathematical idealization, quantification, thought experiment, and limiting one's concerns to the 'how' characterized Galileo's counterintuitive shift away from Aristotle. Virtually all historians of science name Galileo as the first 'modern scientist.' In addition to his scientific accomplishments, he also was credited with writing the best prose of his era. Almost single-handedly Galileo overturned 2000 years of stifling dogmatic belief.

Galileo was immensely popular with his contemporaries. Learned, an inventor, a gifted conversationalist and story teller, a friend of the Pope, he was a sought after guest by people from many levels of society. Were he not so popular and had he not been a friend of the Vatican then surely he would have been burned at the stake for his revolutionary and heretical views.

While he may or may not have been the actual inventor of the telescope, he was its first advocate. Galileo saw to it that telescopes became readily available to scholars and ordinary people. He also saw to it that his name was associated with the device thereby spreading his fame. On one occasion, Galileo invited people to look through his telescope at our moon, the planets and their moons, and the sun and the stars. Interestingly, while looking at the moon only two amongst twenty-four actually saw what we now see. Either they could make no sense out of what they saw or they felt they were being deceived by Galileo. The common world view shared by Galileo's contemporaries was that heaven and earth operate by different laws. Galileo supported the heliocentric views of Copernicus and Kepler but he went further. He demonstrated that there is but one mechanics and dynamics operative both on earth and in the heavens. In creating a new unified view of the cosmos he became our contemporary. Before Newton could espouse his Universal Laws of Nature, Galileo first had to create both new phenomena to observe and new ways to think about phenomena.

To the Ancients, a vacuum was unthinkable. But Galileo conducted a thought experiment. Archimedes had shown that what makes lighter objects sink slower or even float while heavier objects sink quicker depends on the density of the medium. Galileo reasoned that if a medium got less and less dense and in fact became a vacuum, then a heavy and a light object falling through a vacuum would fall at the same rate. It was decades after he died that someone was able to create a vacuum and prove Galileo correct. The ancients had reasoned that light things fall more slowly to the earth while heavier things fall more quickly because that is their nature. Galileo did another thought experiment. What if you tied a light object and a heavy object together. Their combined weight being heavier they would fall faster. But on the other hand, given their different natures, with the slowing effect of the lighter they would fall slower. This thought experiment revealed a contradiction in the Ancient world view.

Galileo stated that the natural state of objects is motion. He refuted the notion that things are naturally in a state of rest. He demonstrated that a ball rolling down a slope picks up speed and that the same ball loses speed rolling up a slope. He reasoned that a horizontally moving body in the absence of friction or opposing forces would naturally continue to move forever. Galileo performed another experiment with balls rolling down an inclined plane. Trained as a musician, Galileo possessed an excellent 'ear'. By putting instrument strings across the plane he was able to hear any differences that the two balls might make as they rolled down. If the heavier rolled faster it should be readily evident to his ear. There were no discordant noises. In another thought experiment he mentally increased the angle of the incline to the vertical thereby approximating free fall. To Galileo, all physical objects must fall at the same rate when one subtracts wind resistance. He was the first to give mathematical expression to the falling object's acceleration. He delineated the notions of speed or position, velocity and acceleration.

Of all Galileo's inventions, the notion of acceleration is the most profound. Distance divided by time equals speed. Speed specifies the rate of a body's displacement, say 55 mph. When we describe speed and the direction of motion we are specifying velocity, say 55 mph to the north. A quantity described by both magnitude (how much) and direction (which way) is called a vector quantity. Velocity is a vector quantity. A quantity described only by speed is a scalar quantity. Constant velocity implies both constant speed and constant direction, i.e., motion is unvarying and along a straight line. Constant speed is not the same as constant velocity. A car on a circular track may have a constant speed but its velocity will be changing at each instant as its direction changes. Acceleration = change of velocity/time elapsed. Acceleration occurs only when there is a change in a body's state of motion. Velocity is the rate at which the position of a body changes and acceleration is the rate at which velocity changes. A change in velocity is a change in its direction or its speed or both its speed and its direction. The rate of change of velocity is acceleration. Acceleration measures how fast things change. It is the rate of change of the rate of change. When in a later article we come to discuss Moshe's ideas about awareness it will be crucial to have some understanding of acceleration.

Galileo maintained that sensory qualities were secondary to primary dynamics. By discounting the evidence of the senses he was able to make relevant abstractions, that is, to use thought experiment and mathematics to provide descriptions that are counterintuitive. To quote, "...Aristotle merely formulated the most commonplace experiences in the matter of motion as universal scientific propositions, whereas classical mechanics ...makes assertions which not only are never confirmed by everyday experience, but whose direct experimental verification is fundamentally impossible... Aristotelian physics thus has the advantage over classical mechanics in that it deals with concrete, observable situations constantly encountered. But from a scientific point of view this very advantage constitutes its weakness..." (The Mechanization of the World Picture: Pythagoras to Newton, E.J. Dijksterhuis. Princeton Paperback, pages 30-31)

By examining the life and work of Galileo and his successors, we can gain fresh insight into our work. The shift from knowing 'why' to knowing 'how' is central to the foundation of the scientific method and of the Feldenkrais Method. Galileo invented the notion of thought experiment so dear to Einstein. The relevance of thought experiments to understanding how to construct lessons is crucial. Galileo literally invented the ideas about gravity and acceleration implicit in our work. Surely any thinking about Functional Integration and Awareness Through Movement which includes the contributions of Galileo and other figures from the history of science will be rewarded.

Republished on this webpage with the friendly permission of Dennis Leri.
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