Some considerations about the two primary means of acquiring knowledge: induction and deduction.

“Everywhere life means questions and answers,” Srila Prabhupada said. We have so many questions in our lives, and we seek satisfactory answers for them. While most of us busy ourselves with questions about our day-to-day survival, job, family, and so on, the Vedic literature urges us to inquire beyond these things, to ask far deeper questions – about our existence, God, the secrets of birth and death. “Who am I?” “Does God exist?” “Why do we die?” “What is the soul?” “What is the meaning of life?” Philosophers call these “existential questions,” questions about our existence. At some point these questions cross our minds. They are serious. They are perplexing.

The world has changed considerably with the advent of modern science and technology. Until a couple of centuries ago, any responsible person pondering over the above questions would get answers from the sacred scriptures. Now, of course, the situation appears different. With the development of modern science, people have explored the depths of the sea and the vastness of the sky. Now existential questions demand an answer with a scientific touch. With both scriptures and science at our disposal, we can acquaint ourselves with the nature of the conclusions they reach. For that, we should know the two processes for acquiring knowledge: inductive and deductive.

The Inductive Approach

This is a bottom-up approach. In Sanskrit it is called aroha-pantha. We all have sense organs: eyes, ears, nose, skin, and tongue, and we use them to perceive the world and gather information. In the inductive approach, we observe the world through our sense organs and then use our mind and intellect to infer conclusions about the observations. Modern science emphasizes this approach and uses it to propound theories about the origin of the universe, the origin of life, and so on. We all know that our sense organs have limitations. For example, our ears can hear only in the frequency range of twenty hertz to twenty kilohertz. We cannot see objects on earth beyond a few kilometers. Our sense of smell is also limited. Scientific instruments help us to some extent, compensating for the deficiencies of our senses.

We use the instruments to observe the world, and then we speculate to reach conclusions we hope to be correct. For example, scientists use powerful telescopes to study celestial objects near and far. They classify and name them. In my school days, I happily learned that our solar system has nine planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. The last one is special. Pluto was discovered in 1930 and was considered the smallest planet and the farthest from the sun. The year 2006 was somewhat bad for Pluto. The International Astronomical Union (IAU), the scientific body responsible for naming and classifying objects in the cosmos, redefined the term planet, and according to them Pluto did not fit in the category. Its planet status was revoked after seventy-five years. They demoted Pluto to “dwarf planet,” reducing the number of planets in our solar system to eight. This upset the public and several planetary scientists, who questioned the new definition of a planet.

A team of NASA scientists is planning to make Pluto a planet again. The group, led by Alan Stern, the principal investigator for the New Horizons mission to Pluto, has submitted a proposal to the IAU suggesting a new definition of a planet. Mr. Stern’s team argues that the definition employed by the IAU is technically flawed. Under the new definition offered by the NASA team there would be at least 110 known planets in our solar system. Imagine the plight of students with all this yo-yo science.

The above narration gives us a glimpse of the inductive approach along with its shortcomings. In general, any inductive undertaking is time consuming and leads to imperfect conclusions. For example, a man inductively observing many people die around him may not conclude that he might also die one day.

Srila Prabhupada: The essential fault of the so-called scientists is that they have adopted the inductive process to arrive at their conclusions. For example, if a scientist wants to determine whether or not man is mortal by the inductive process, he must study every man to try to discover if some or one of them may be immortal. The scientist says, “I cannot accept the proposition that all men are mortal. There may be some men who are immortal. I have not yet seen every man. Therefore how can I accept that man is mortal?” This is called the inductive process. (The Science of Self-Realization, chapter 6)

The Deductive Approach

The deductive* approach is a top-down scheme. In Sanskrit it is called avaroha-pantha. Imagine that our friend Mr. A. does not know who his father is and wants to find out for himself. If he chooses to employ an inductive approach, then he will have to conduct scientific research – most probably genetic fingerprinting or DNA paternity testing. Who would be the candidates under research? Ideally Mr. A. has to collect DNA samples from all the eligible, potent men on earth who could have fathered him whatever time ago. Of course, that would be a lot of men. We could narrow down the sample set to men in his city. Still it is a huge number. Some of them might be alive; some might have died. Since fathering is a private act, some candidates might feel offended and refuse to give their samples. Some people’s DNA composition might have mutated over the years. The tests take time because all the samples must be tested. Samples risk being contaminated, creating erroneous results. The DNA tests provide a probability of parentage against each sample, where a probability value of 99.99% is considered the most “likely” father. After this entire ordeal, we are not sure if Mr. A. would still be alive. If alive, he’d probably be bankrupt by funding the project. Worse, would his heart be satisfied with the whole enterprise?

Srila Prabhupada: Therefore our speculative knowledge, intellectual platform, is not helpful. We must receive knowledge from a superior source, a perfect source. That knowledge is perfect. Just like we give generally this example, that to find out who is my father, my research will not help me, but if my mother says, “Here is your father,” that is perfect knowledge because she’s the authority. Therefore, for perfect knowledge, we have to take it from the perfect authority, not by our speculative intellectual gymnastics. No, that will not help. Because our intellectual jurisdiction is very limited. . . . The Vedic process is not to acquire knowledge by the ascending process, the inductive process. Vedic knowledge is to receive knowledge by the descending process, knowledge coming from authority. (Conversation with a Professor, December 9, 1973, Los Angeles)

Accepting knowledge coming from perfect authority is called the deductive approach. In this approach, an eternal, infallible, absolute authority is accepted at the top level. The knowledge received from the authority serves as a primary beacon with which we acquire subsequent knowledge. In the deductive approach, the limitations of sensory observations and mental speculations are honestly acknowledged and hence subordinated to an authoritative knowledge. So if Mr. A. consults his mother, his question is answered conclusively, decisively, and reliably. She is the authority. Her words can be accepted. A simple and effective method.

Srila Prabhupada: We have to accept things which are accepted by authorities. That is our education. We go to a teacher. We go to school. We learn from father, mother. They’re all authorities. And our nature is to learn. “Father, what is this?” In childhood. Father says, “This is a pen. This is a spectacle. This is a table.” . . . So similarly, if we get information from the authority, and if the authority is not a cheater, then our knowledge is perfect, and very easy. Just like, the father, mother never cheats. When the son inquires from the parents, the parents give exact information, right information. Similarly, if we get right information from the right person, that is perfect knowledge. If you want to reach the conclusion by speculation, that is imperfect – inductive process. That will never become perfect. It will remain imperfect for all the time. (Lecture, July 20, 1971, New York City)

Each of us starts getting knowledge through the deductive process right from our childhood. We get guidance from our parents, teachers, and well-wishers in making sense of the world and using our intelligence judiciously. This process of placing our implicit faith in the authority seems innate and natural. It is only after we have acquired (deductively) a basic theoretical understanding that we can begin an inductive process. Nonetheless our instinctive inclination to the deductive approach remains lifelong. For example, scientists deductively accept axioms as authoritative truths while they continue with their inductive process. In our day-to-day life also, we accept the authority of doctors, judges, traffic police, and so on. Either willingly or unwillingly, we accept authorities; the deductive approach is inescapable.

Srila Prabhupada: From the beginning of your life, when you were a child, you asked your parents, “Mother, father, what is this?” Why? That is the beginning of life. You cannot go even a step without authority. You are governed by authority. You are running your car by authority – “Keep to the right.” Why? Why don’t you defy it? So authority we have to obey. But the difficulty is: who is the authority? That we require to learn – who is actually the authority. (Lecture, June 15, 1968, Montreal)

The Authoritative Trio

The Vedic processes prescribe what should be the nature of the authority. It is not that we accept any arbitrary person as an authority based on some dogma. The authority is expected to be perfect, scientific, sensible, intuitively appealing, and self-evident. Such an authority is the trio guru-sadhu-shastra. They are like the three legs of a tripod, together supporting the knowledge of the Absolute Truth. A guru is a bona fide spiritual master, like Srila Prabhupada, coming in an unbroken disciplic succession from Lord Krishna. Sadhus are others in such bona fide disciplic successions, including great spiritual preceptors like Ramanujacharya. A shastra is a scripture, such as the Bhagavad-gita and the Srimad-Bhagavatam. Each member of the guru-sadhu-shastra system speaks the same truth without contradictions. They provide a perfect authority because they are free from the four defects: (1) imperfect senses, (2) the cheating propensity, (3) the tendency to be illusioned, and (4) the tendency to commit mistakes. Such is the high standard of the accepted authority in the Vedic process. It is a serious business.

How serious should we be in our pursuit to seek answers to the existential questions? Quite serious. The guru-sadhu-shastra system addresses such questions primarily. These questions are not on the same level as deciding whether some distant, cold, icy place called Pluto is a planet or not. For most of us, that question is irrelevant. Real life is quite different from isolated scientific laboratories. The day-to-day experience of life is a dynamic interplay of emotions, relationships, values, ethics, death, love, anger, passions, purpose, lust, hate, and so on. These experiences are closer to the bone, and we grapple to make sense of them in a satisfactory way. To subject these important aspects of life to the time-consuming trial-and-error method of inductive research seems a misplaced choice. The inductive approach may have its uses, but we should remember that its conclusions may not be perfect. This imperfection makes a big difference.

The deductive approach of the guru-sadhu-shastra system provides a solid framework that can be used to seek answers to existential questions in a meaningful way. Guru, sadhu, and shastra reinforce one another, providing a stable reference for our lives.

Sometimes contradictions may seem to appear in the deductive approach. Srila Prabhupada often addressed this with the example of cow dung. In his introduction to Bhagavad-gita As It Is, he writes:

All Vedic knowledge is infallible, and Hindus accept Vedic knowledge to be complete and infallible. For example, cow dung is the stool of an animal, and according to smriti, or Vedic injunction, if one touches the stool of an animal he has to take a bath to purify himself. But in the Vedic scriptures cow dung is considered to be a purifying agent. One might consider this to be contradictory, but it is accepted because it is Vedic injunction, and indeed by accepting this, one will not commit a mistake; subsequently it has been proved by modern science that cow dung contains all antiseptic properties. So Vedic knowledge is complete because it is above all doubts and mistakes, and Bhagavad-gita is the essence of all Vedic knowledge.

Modern science tries its best to discover (inductively) in a rather slow way – in bits and pieces, with trial and error – to reach a conclusion that a Vedic scripture might have simply stated (deductively) a long time ago. We should be cautious about induction-based criticism of the authority of the deductive method. We should carefully consider the relative merits and demerits of the inductive approach and use it as the situations demand. The inductive approach is speculative and may be helpful in certain areas, but for much of life – love, God, purpose, soul, morality, and so on – a deductive approach would do a reliable and satisfactory justice.

Therefore it is wise for us to embrace the deductive approach. How do we begin? Speaking to Arjuna, Lord Krishna describes the first step:


tad viddhi pranipatena
pariprashnena sevaya
upadekshyanti te jnanam
jnaninas tattva-darshinah


“Just try to learn the truth by approaching a spiritual master. Inquire from him submissively and render service unto him. The self-realized souls can impart knowledge unto you because they have seen the truth.” (Gita 4.34) In the purport, Srila Prabhupada writes: “One should not only hear submissively from the spiritual master; but one must also get a clear understanding from him, in submission and service and inquiries.”Here we see that the deductive approach includes questions and answers – clarification of doubts with an open mind. It is not dogmatic. It involves using the faculties of the senses, mind, and intelligence, but with a proper understanding of their powers and limitations.

Broadening the Scientific Perspective

Several great scientists understood the limitations of the inductive method. Who does not know Sir Isaac Newton, the father of mechanics? Even today, after three hundred years, we use Newton’s laws of motion to launch rockets and satellites into space. We use his theory of optics to make telescopes and study the properties of light. We use calculus, his invention, a special branch of mathematics. His contributions to modern science are profound. But he said, “Gravity explains the motions of the planets, but it cannot explain who sets the planets in motion.” Although Newton mathematically formulated the laws of motion, he was aware that the origin of such laws could not be explained. Why the gravitational force is the way it is continues to amaze the best scientific brains even today. Newton took a spiritual perspective alongside the material perspective. He marveled, “This most beautiful system of the sun, planets, and comets could only proceed from the counsel and dominion of an intelligent and powerful Being.”

This intuition of one of the greatest scientists should inspire us to keep an open mind and welcome spiritual considerations. Srila Prabhupada encouraged such a thought process. He desired that a magnificent Vedic planetarium be built in Mayapur, showcasing the elaborate astronomical model given in the Srimad-Bhagavatam. Let us hope many modern space scientists visit this place and get inspired to know the scientific topics included in the great classic Srimad-Bhagavatam.

*In this article I’m using the term deductive in the way Srila Prabhupada used it (i.e., received from authority), rather than as the dictionary defines it: “based on deduction from accepted premises.”