When Professors Make Dubious “All” Generalizations

We can make a classification of different types of generalizations that a scientist might make about nature. 

Type	Examples	Reliability
“Some” generalizations	"Some deaths are caused by cancer." "Some craters are caused by meteors."	“Some” generalizations can be fairly reliable if supported by an observation showing that in at least one case the generalization holds true.
“Many” generalizations	"Many deaths are caused by cancer." "Many craters are caused by meteors."	“Many” generalizations can be fairly reliable if supported by  observations showing that in multiple cases the generalization holds true.
“Most” generalizations	"Most waves are made of water." "Most birds have wings."	Many “most” generalizations are false, because they are not backed up by any numerical evidence justifying the use of the word “most.” Example: the claim that most mental illness is caused by chemical imbalances.
“All" generalizations	"All things are made of atoms."	Very many or most generalizations using the word “all” are  unreliable. Some of these generalizations may be very large untruths. Typically it is all-but-impossible to prove an “all” generalization. Alarm bells should go off in our minds whenever we hear someone making an "all" generalization.

Some of the most important “all” generalizations made by scientists have been just plain false.  Scientists once assured us that all heat consists of a fluid called "caloric" flowing from one body to another.  The theory has been disproved. 

Ideally, scientists would follow the practice of not claiming that most things of some type are caused by some particular thing until it was proven that some things of that type are caused by that particular thing; and they would not claim that all things of some type are caused by some particular thing until it was proven that most things of that type are caused by that particular thing. In reality, no such "horse before the cart" rules are followed.  What often happens is that scientists often assert that all things of some type are caused by some particular thing before it has been proven that any thing of that type is caused by that particular thing.  For example, a scientist who is having difficulty selling the idea that some particular mental illness is caused by a chemical imbalance may start teaching that all mental illnesses are caused by a chemical imbalance, even though it has not been proven that any mental illnesses are caused by a chemical imbalance. And the claim that all biological innovations are caused by random mutations was confidently asserted before it was shown that any biological innovation was produced by such a thing. Assertions this presumptive may have argumentative advantages in that they may result in a more forceful rhetorical snowplow. A man asserting "all x's are caused by y" may inspire more confidence than one more humbly asserting "one x was caused by y." 

Scientists have asserted innumerable times that all things are made of atoms. A resounding statement of this dogma was made by the leading physicist Richard Feynman, who stated the following:

“If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms—little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another.”

Here we have a ringing endorsement of the claim that “all things are made of atoms” – a statement by Feynman that makes it sound like such a claim is the Supreme Truth of science. But the frequently made statement that “all things made of atoms” is actually false in several important ways. For one thing, we have thoughts and ideas that are not made of atoms. For another thing, we visually observe some important things that are not made of atoms. A lightning bolt is not made of atoms, but of electrons and photons.  Moreover, we know of various subatomic particles such as protons, neutrons and electrons that are the building blocks of atoms.  These things are not at all made of atoms.  It would seem that the claim that "all things are made of atoms" only made sense when scientists thought that atoms are indivisible particles not made of other things.  

Not made of atoms

Moreover, strictly speaking it is not even correct to say that the sun is made up entirely of atoms or even to say that the sun is mostly made of atoms. An atom is defined as a unit consisting of an atomic nucleus and one or more electrons. Dictionary.com defines an atom in this way: “the smallest component of an element having the chemical properties of the element, consisting of a nucleus containing combinations of neutrons and protons and one or more electrons bound to the nucleus by electrical attraction; the number of protons determines the identity of the element.” But the sun does not contain mainly atoms defined in such a way. The sun consists of a very hot gas containing (1) individual protons, (2) ionized electrons that move around freely without being associated with any proton or atomic nucleus, and (3) helium nuclei consisting of two protons bound together by the strong nuclear force. None of these things is an atom, using the most common definition of an atom.

The sun makes up most of the mass in our solar system. So far from it being  true that “all things are made of atoms,” it is not even true that most of the matter in our solar system consists of atoms. Most of the matter in our solar system is in a hot solar gas that does not consist of atoms (using the most common definition of atoms).

There is an additional reason why the “all things are made of atoms” dogma isn't true. Scientists nowadays tell us that most matter in the universe is not regular matter made of things like protons, electrons, neutrons and atoms, but instead some other very different unknown type of matter called dark matter. But scientists have no understanding of the nature of such dark matter, and have no reason to suspect that it consists of atoms. Since most of the universe's matter is believed to be dark matter radically different from atomic matter, it apparently is not even true that most of the universe's matter consists of atoms.

So the statement that “all things made of atoms” is false in several important ways, even though such a statement has been asserted as a “fact of science” by innumerable scientists in the past 50 years. It would seem that our scientists are prone to make dubious "all" generalizations. So should we then be the least bit surprised if in the future other “all” generalizations claimed to be “facts of science” – such as the claim that all life forms descended from a common ancestor, or that all thoughts come from brains – end up being discarded in the future?