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Knowledge by Explanation in Science and Medicine

Updated on March 4, 2014

Science cannot advance without knowledge by explanation

Knowledge by explanation

Knowledge by explanation is similar to knowledge by description. (I have a Hub “Knowledge by description transfers knowledge by acquaintance”) To recall, knowledge by description involves symbols that represent facts. Such symbols could be alphabet or numbers. “R” can represent radious. Letters of the alphabet can be combined to represent sound or material things as we commonly know them. For example, “sun” ultimately represents “a round, hot thing in the sky” we have known from childhood. Note that “a round, hot thing in the sky” is a description.

The description takes care of the transition from a fact in the universe to symbol then existence of the sun, for example. It seems to be a peculiarity of man to make such a description. A cat does not make a description in the sense that it has not devised an alphabet or written a symbol. However, the cat has a mental symbol of a rat. When it hears a quirking the cat knows that there is a rat. The quirking is an unwritten symbol for the rat.

Knowledge of the rat by the cat consists of the cat chasing the rat. This is knowledge by acquaintance. A student acquires knowledge by acquaintance in physics by weighing a stone, for example. A doctor acquires knowledge by acquaintance by vaccinating a child; or operating on a heart.

Given that the distinction between knowledge by description and knowledge by acquaintance is fairly established, we can proceed to knowledge by explanation. This is ultimately derived from knowledge by description. However, it appears useful to make a fine distinction between knowledge by description from knowledge by explanation.

Take this statement in knowledge by description:

“A stone you throw up in the air falls down.”

From childhood this sentence has become commonplace that it is taken for granted.

Then you ask: how is this so? You are asking for an explanation.

Your answer may be: “The stone falls down because it has weight.”

However, a physicist will give another explanation.

He may say: "The stone falls down because of gravity in the Newtonian theory. Gravity is a force that attracts the stone. That force is measured in weight."

Another scientist may say: "The stone will fall down because of gravity in Einstein’s generalized theory of relativity. Gravity is a a curvature of space-time. The stone obeys space-time."

Note briefly that in Newton’s theory, gravity is a force. In Einstein’s theory gravity is the curvature of space time. People living near the surface of the earth make use of Newton’s theory. An astronaut in space flight uses Einstein’s theory otherwise he could not return to earth.

The statements involving force and space-time are explanations. Each explanation consists of separate statements in knowledge by description.

We will clarify knowledge by explanation further by way of examples.


Edward Jenner immunized people against the smallpox by injecting some amount of cowpox. Louis Pasteur immunized people against rabies. Robert Koch immunized against tuberculosis. Immunized people do not get the disease of smallpox, or rabies, or tuberculosis.

How? For a long time Jenner, or Pasteur, or Koch could not explain. Then someone came up with an explanation.

The weakened tuberculosis microbes incite the immune system of the body. The T helper cells alert the T killer cells of the presence of a foreign body. It also alerts another immunity cells, the B cells, particularly macrophage. The macrophage engulfs microbes. It also latches an antigen on the surface of microbes that serve as target. T killer cells find the microbes by means of the antigens and produce antibodies against the microbes. When the tuberculosis microbes had been killed or ejected out of the body, most of the T helper cells, T killer cells and B cells will die off. However, some B cells will remain as memory cells. When tuberculosis microbes will invade the body, these memory cells will incite the T helper cells, T killer cells and B cells to multiply and kill and eject the microbes. Immunization is attained.

The process of immunization is a little more complex but the above elaboration gives the essentials.

This elaboration is an explanation; an example of knowledge by explanation.


When a fellow with heart disease has chest pain or angina pectoris, s/he is administered a tablet of nitroglycerin (Isordil, Imdur). The chest pain is alleviated.

How? For a long time that nitroglycerin alleviates angina was not explained. However, doctors administered nitroglycerin because it gave the desired effect. The explanation is as follows:

Robert Futcgott found that the inner wall of the arteries of the heart (endothelium) produced a gas he called endothelium-derived relaxation factor (EDRF). This dilates the artery that allows more blood flow, thus angina is alleviated. Angina is brought on by the starvation of heart muscles for oxygen owing to lessened blood that carries oxygen.

Ferid Murad found that nitroglycerin produced nitric oxide, a gas free radical, that served as a messenger for the artery to dilate.

Louis Ignarro found that EDRF and nitric oxide are the same.

That is, nitroglycerin produces nitric oxide that dilates arteries. Dilated arteries allow more blood flow resulting in more oxygen to the heart. Finally, angina is alleviated.

Futcgott, Murad and Ignarro were awarded the Nobel Prize for medicine in 1998.

Why do we need knowledge by explanation?

Knowledge by explanation is part of science. For one, it makes for a hypothesis that is a scientific guess used as a guide in doing experiments. A hypothesis consists of concepts and relationship(s) between concepts.

For example, E = mc2

The concepts are E (energy), m (mass) and c (speed of light). The relationships are equivalence, and multiply (that includes squared).

Suppose we knew only of nitroglycerin and nitric oxide. We come up with the hypothesis:

“Nitroglycerin produces nitric oxide that dilates an artery.”

The concepts are “nitroglycerin,” “nitric oxide” and “artery.” The relationships are “produces” and “dilates.” To verify this hypothesis, a doctor administers nitroglycerin to a patient experiencing chest pain. The chest pain is alleviated. In that case, the hypothesis is verified. Now, the hypothesis graduates into a theory.

A theory consists of concepts and relationship(s) between concepts that had been verified (Einstein, A. Ideas and Opinions. 1954).

The above example is a simplified way of doing science with knowledge by explanation. Using this theory, a doctor or a patient brushed up on this theory can take a tablet of nitroglycerin confident that his angina will be alleviated. That is, theory explains; it also predicts (Campbell, N. What is Science? 1921).


Knowledge by explanation is important. Take one example in medicine.

Chemotherapy is applied to treat cancer.

Question: how does chemotherapy treat cancer?

Explanation: chemotherapy kills cancer cells.

Question: how does chemotherapy kill cancer cells?

Conventional medicine does not come up with an explanation. It is probable that conventional medicine has an explanation that is true. However, it has not been giving one.

This explanation, if any, is a theory. And medication based on this theory is effective because a theory predicts. This prediction is accurate, in the same way that a stone thrown up not too far out will fall down. Prediction is accurate in the same way that a nitroglycerin will alleviate angina.

The explanation of how chemotherapy treats cancer is as follows:

A chemo drug, like adriamycin, produces a lot of free radicals. These free radicals destroy the membranes and nucleus of cancer cells resulting in death. They destroy the membranes and nucleus by grabbing electrons from them.

Question: how does chemotherapy produce side effects?

The explanation is as follows:

A chemo drug like adriamycin produces a lot of free radicals that also kill healthy cells in the vicinity of cancer cells. These healthy cells are usually red blood cells, white blood cells, platelets, hair cells and stomach cells. That is why during chemo treatment blood count decreases, hair loss occurs, and nausea or vomiting occurs.

The above explanations are not usually given to patients before treatment with chemo. Only the kinds of side effects are told.

It is highly probable that a lot of doctors do not know the free radical explanation of how chemotherapy treats and how it produces side effects. .

It is highly probable that medical researchers in cancer do not know of the free radical explanation. On the other hand, it is also highly probable that medical researchers in cancer know of the free radical explanations but are not applying them. The reasons do not fall within medicine. They fall within economics, that of profit motive.

Knowledge by description, by acquaintance and by explanation are useful or bad according as to how we use them. The use of E = mc2 in making atomic bombs is bad. Its use in generating electricity is good.

Without knowledge by explanation, science cannot advance.Predictions and their verifications make for advances.

Philosophy of science

Satisfaction with mere knowledge by description comes from positivism in the philosophy of Comte. He rules out explanation of facts, like light of the sun. He also rules out the use of hypothesis, or scientific guess in conducting experiments (Russell. B. Wisdom of the West. 1959:376-380).

Since theory is a result of verified hypothesis, no theory could come out without a hypothesis.In medicine knowledge by description is not enough, like vaccination without an explanation. If that were so, there would hardly be an advance in medicine. Take the case of the vaccine for poliovirus that causes polio. Vaccination with weakened virus gave satisfactory results. But Dr. Jonas Salk believed that a killed poliovirus also serves as vaccine. He had a tacit hypothesis for this. He proved it in practice. But he did not come out with an explicit theory.

This theory is:

"The size and shape of killed poliovirus incite immunization."

I discuss this theory in my Hub with a similar title. The immune system reacts to the size and shape of killed poliovirus. Salk preserved such size and shape by killing and hardening the virus with formalin. This technology is far more advanced than the live attenuated polio vaccine or OPV. In OPV the weakened virus can mutate, become virulent and infect. That is why OPV is still a carrier of poliovirus. In Salk vaccine, the virus is "dead" in that it can infect and multiply, according to Salk.

This theory explains the accomplishments of the Salk killed poliovirus vaccine. Now this theory enabled another scientist to come out with a vaccine against hepatitis B virus. This vaccine consists of protein coats without DNA. (Hepatitis B virus is a DNA virus). The gene that controls the production of protein coat of hepa B virus was isolated and inserted in yeasts. This technology is called recombinant DNA. The yeasts produce a lot of hepa B protein coats that are being used as vaccine against hepa B. In layman's language protein coat is the dead component of hepatitis B virus; the DNA is the live component.

Without the work of Dr. Salk and the tacit theory that I have formalized, there would have not been a scientific basis for the hepatitis B vaccine. The immune system reacts to the size and shape of the protein coat.

That a theory also predicts insures that shots of killed poliovirus vaccine will immunize. Without this prediction, this vaccine would not be used in a national, albeit worldwide, program of immunization against polio.

The explanation of how chemotherapy kills cancer cells comes from the free radical framework. That free radicals kill cancer cell is proven with the use of inducible nitric oxide, a free radical, in gene therapy for cancer (Nitric Oxide Protocols. 2nd edition). The use of chemotherapy already proves that. A chemo drug like adriamycin (doxorubicin) produces a cascade of free radicals (Sharma, H. MD.Freedom from Disease. 1993). Chemo drugs produce singlet oxygen, a free radical (Pressman, A. H. D.C., Ph.D. C.C.N.and S. Buff. Glutathione: The Ultimate Antioxidant. 1998).

Now medical research and development of treatments and cures for cancer can advance more rapidly if the free radical framework were applied.

That this is not so is owing to barriers being put up by Big Pharma that profits from conventional drugs used in the unsuccessful fight against cancer.

The desire for the explanation of how chemotherapy works reveals its secrets. This knowledge by explanation leads to better prevention, halt and cure for cancer. The gene therapy against cancer cures cancer without side effects. Unfortunately, this therapy is not yet in the market. I have three Hubs on this topic.

A theory explains when it is not itself the object of an inquiry, according to Russell. (Russell was a British mathematician and philosopher, winner of Nobel Prize in literature/philosophy). Take the conventional explanation of chemotherapy: "It kills cancer cells." However, this explanation is a subject of inquiry by the free radical framework. Now the free radical explanation is more valid and true that is why it supersedes the conventional explanation of chemotherapy. The conventional explanation of how chemo kills cancer cells is in the tissue level. The free radical explanation of how chemo kills cancer cells is in the molecular level. So far, the free radical theory is not an object of an inquiry whose resolution can probably supersede it.

Knowledge by explanation holds true for the whole of science.


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