Scientific Homonyms

Sometimes the same word can have two (or more) meanings. As I think about this today (a Sunday), the word “spirit” comes to mind. I actually started thinking about that word, spirit, since last Sunday, when this atheist attended church. My thoughts have not been focused on the subject, but it has been dancing in and out of my head; how could I, an atheist and a materialist, also be spiritual? The answer, it has occurred to me, is that there is no real contradiction.

Rather, the issue is that any conflict between being an atheist and a materialist, and being spiritual at the same time, is merely a confusion seated in convention. The words we use are agreements; we agree that words denote and connote certain meanings. However, some words are homonyms, i.e., the same word can have multiple meanings. This is why I call words and their meanings conventional.

That said, I presently turn my attention to what I call scientific homonyms. I will discuss three here, though three is a very limited selection of what I’m certain are a great many that could have been chosen; but I think that three will be enough to suffice. I am seeking to illustrate what I’m talking about, not to write an unabridged dictionary of scientific terminology or to write at encyclopedic length.

Therefore, I constrain myself to a brief discussion of “aether”, “gravity”, and the word that brought me to write this article, “spirit”.

1. Aether.  The history of science is marked by paradigm shifts. From the pre-Socratic philosophers through modern age scientists, various theories (philosophical and scientific) have been proposed and supplanted. In a time when the terrestrial realm was thought to be of a different kind than the celestial realm, Aristotle believed that the four terrestrial elements were earth, wind, water, and fire; the celestial realm was made of aether. To Aristotle, the elements of the terrestrial realm gave objects on Earth either levity or gravity (discussed ever so briefly below), which explained their motion, whereas the celestial objects were made of aether and did not move. Aristotle’s aether was not quite the same thing as the aether that Michelson and Morely subjected to experimentation, with Michelson’s interferometer, in 1887. By the 19th Century, ideas about optics had changed immensely from the time of Aristotle. Aristotle thought that light was emitted by the eyes to perceive objects, but light, it was learned in the interim, was discovered to travel to the eyes from luminous objects, not from them. But if space is really all that spacious, then, an explanation for how celestial objects get their light from their locations in the heavens to Earth needed an explanation. Light, it was thought, must travel through a medium, and that medium was the 19th Century’s aether — still a celestial element, I suppose, but not quite the same as the Aristotelian aether.
2. Gravity. Returning to Aristotle, and reiterating portion of what I state above, Aristotle had his own idea of what made objects in the environment move. Objects were made up of combinations of earth, air, wind, and water. Depending upon its constituent elements, objects had more or less gravity or levity. Gravity was the tendency of things to move towards the center of the universe, whereas levity was the tendency to move away from the center. For example, the more of the element earth that an object had, the more gravity it would have. Newton proposed a different definition of gravity in 1687. Newtonian gravity is a force that attracts two bodies to each other’s center of mass that is directly proportional to the product of their masses and inversely proportional to the square of their distance from each other. Newton’s gravity, in turn, is different than Einstein’s gravity, which explains gravitational force by the curvature in space-time created by an object’s mass bending the fabric of space-time.
3. Spirit. This is perhaps the trickiest of the three homonyms that I am discussing in this article. The reason that I must give for it being so difficult to explain in a few words is that the word “spirit” is more a subject belonging to the domain of psychology than of physics. Psychology is much more difficult a science than physics, so to speak of aether and gravity is comparatively easier than to speak of spirits. Allow me to go back to Aristotle. Aristotle wrote On The Soul around 350 B.C.E. The word “soul” is tied up with two other words: “spirit” and “mind”. Part of the human soul that sets it apart from animal souls, if I understand Aristotle correctly, is that the human soul has a thinking component, or what might be called cognition. When I think of cognition, it is my brain thinking about itself; put another way, to me in the 21st Century, I see the mind as the function of the brain. Not so for Aristotle, however. The Aristotelian mind emanated from the heart. For Descartes, in the 17th Century, got closer when he moved the soul/spirit/mind to the pineal gland, but the pineal gland isn’t the cerebral cortex. For many philosophers through the ages, and for many laypeople today, the human spirit is a soul that is separate from the material body, and it lives on after death in some supernatural sense. To me, the spirit is the mind, and the mind the function of the brain, and the brain is a material thing; but there is a lot of mind, or spirit, that that brain can generate!

The three terms listed above are just a few examples of how words, which we use arbitrarily, can be misleading if we do not make clear what our conceptual definitions of them are. While I am no mathematician, I am a positivist — which I suppose goes hand-in-hand with materialism — so I add that operational definitions are also important, at least when it comes to science. If you can measure it, it doesn’t exist. What, then, does exist? I mean, what truly does? Are some uses of homonyms true, whereas others are false? Was Einstein more correct than Newton, and Newton more correct than Aristotle? To attempt to answer those questions would lead me too far astray for this article.