Humans Cannot Have Certain Knowledge, and Considerations of that Fact


A problem in epistemology, Munchausen’s Trilema demonstrates that any theory of knowledge, including in mathematics, science and logic, cannot be certain and that no human beliefs, theories or models can ultimately be proven certain. Baron von Munchausen was a teller of tall tales and fantastical arguments, including that he impossibly pulled himself out of quicksand by pulling himself up by his own ponytail.

All statements of knowledge can be questioned as to their veracity, and, for certainty, must be proved true. The trilemma says there are three ways to try to answer questioned statements: 1) circular argument, 2) infinite regression or 3) axiomatic argument. Each proves to be incapable of finding certainty. 



  1. Circular reasoning, or begging the question


This is when you essentially use the statement to (try to) prove it true:


John: “God is real.”

Mary: “What is your justification for believing that true?”

John: “The Bible says God is real.”

Mary: “What is your justification for believing the Bible is true?”

John: “It is the word of God.”


This is circular reasoning with John saying God is real because God is real and says so


Nancy: “My sight is reliable?”

Pat: “Why do you say that?”

Nancy: “Because my eyes see that apple.”

Pat: “How do you know the apple is real and really there?”

Nancy: “Because I can see it right sitting right there.”

Nancy is basically arguing that her sight is reliable because her sight is reliable.


A logician saying logic is accurate because logic has shown this is circular reasoning. Science saying science proves that science is reliable is another example. No belief system, theory or way of thinking can prove itself true.


2) Infinite regression

This is like the young child who continually asks “But why?” to every answer you give. 


A is true because of b

B is true because of c

C is true because of d

Repeat until infinity


Carl: “My sight perception is an accurate perception of reality?”

Charlie: “How do you know that?”

Carl: “Because I took an eye test last week.”

Charlie: “How do you know the eye test is reliable?”

Carl: “Because it was performed by an optometrist who is an expert in eyes,”

Charlie: “How does the optometrist know that eyesight is an accurate representation of physical reality?”

Repeat until infinity or one quits in frustration or boredom or one or both of the two quit.


Some like this line of reasoning, at is the line of reasoning used in science, because it can involve lengthy analysis and, with proper arguments, the arguments will not be shown to be wrong. But it will never reach certainty because the questions continue forever without a final answer. 

Some philosophers say infinite regression is an elongated way of saying “I don’t know” or “I can’t be certain.” However, good long arguments can be considered ‘provisional truths,’ meaning working answers that are considered true for the time being, though may be found to be false in the future. However, it is likely that longer along the line you get, you will find questions you can’t answer or something that contradict the belief.

“The more deeply we explore any subject matter the more surely we are going to arrive at unexplained phenomena which challenge the entire framework of our quest for knowledge . . . The pursuit of knowledge is the pursuit from comprehension to incomprehension. We always start with something we know fairly well and end up with big puzzles.” – Philosopher Henryk Skolimowski, The Participatory Mind.

This says humans must be prepared for their rules to possibly if not probably be proven wrong, or at least having exceptions and needing refinements.


3) Axiomatic argument

This involves making unproven and often unprovable assumptions, or axioms.


John: “My sight perception gives a reliable view of physical nature.”

Nancy: “How do you come to that answer?”

John: “I assume my perception is reliable. Don’t you assume yours is?”


All human endeavors and conceptions, including yours and mine and the most famous scientists and philosophers, involve unproven or unprovable assumptions.

Circular reasoning, or begging the question, can be considered really to be axiomatic reasoning. “I believe God is real, because (I assume) God is real.”


Godel’s Incompleteness Theorems

Kurt Godel’s incompleteness theorems also illustrate the limits of knowledge and certainty within theories and models, both scientific and unscientific.

Mathematician and logician Kurt Godel’s incompleteness theorems showed that no closed system can prove everything and cannot be used to prove its own accuracy or everything within its own system. The latter is similar to the philosophical fact that “A human cannot determine the accuracy of its own mind, because the tool used to test and judge the accuracy (its mind) is of undetermined accuracy.” Gödel’s incompleteness theorems show that any logical system either has contradictions or statements that cannot be proven.

And if you add parts to the system in an attempt to check a closed system’s reliability, you’re merely created a larger closed system. Godel’s theorem cannot be escaped.

At a time when mathematicians and philosophers were trying to create a logical and neatly structured system to show everything, Godel’s theorems were considered earth-shattering and today are ranked as landmarks in the history of mathematics, science and philosophy.

They also demonstrate that today’s physicists trying to create a certain “Theory of Everything” are playing a fool’s game.

Gödel’s discovery not only applied to mathematics but all branches of science, logic and human knowledge.



The Munchausen Trilemma and Godel’s Incompleteness how certain knowledge, including in science and logic, is unattainable.



While it is simply fact that humans can’t have certain knowledge, there is a wide variety of considerations and opinions about the significance and relevance of this uncertainty. 

To some, the lack of knowledge is of profound relevance. If one is concerned with the search for metaphysical and objective truths about reality, the inability to even know the reliability of one’s own sensory perception and mind is of profound significance and often deep disappointment. 

To others, the uncertainty does not bother them or is irrelevant to their practical purposes and interests. I have a hardcore atheist medical scientist colleague at Oxford, and I asked her for her philosophy behind her atheism. She said she intentionally removed the question and topic of God from her life, so she could focus on other things. 

Some may rightly say that, yes, there is uncertainty in all things including science, but science still produces reliable results within its scope and purpose. There is much unknown about quantum physics but it produces usable results and practical products. There are uncertainties and biases in engineering, but it builds sturdy bridges and working cars. To many engineers, the inability to know metaphysical meaning and many areas lay outside of science, is beside the point to their work. 

Further, humans have evolved to function in ambiguity and uncertainty. They were born, raised and go about our lives not knowing many things, have evolved to act in social situations where they don’t know and can’t know what others think, act and make decisions for an unknown future and ambiguous present. The human ability to function, survive and thrive in an environment of constant uncertainty and ambiguity is a great skill. 

Some people simply can psychologically live in uncertainty better and more contentedly than others. Some psychologically “need answers and for there to be answers,” while others do not.

And many of the greatest and proudest achievements of humans are the products of uncertainty. Many great and moving artworks, many scientific and knowledge discoveries, are the products of being faced with mystery. 


‘Where Do We Come From? What Are We Doing? Where Are We Going?’ by Paul Gauguin (1897)

However, whatever one’s opinion, consideration or viewpoint on the limits of one’s knowledge, the lack of uncertainty is a fact.