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Certainty Versus Uncertainty

06 Jun 2019 . category: science . Comments
#uncertainty #certainty #randomness #probability #psychology

The big question

Does absolute certainty exist? Can you be certain that event x will occur? If yes, are you certain it will occur in time y? [Wiener, Norbert] assert that most people would expect absolute certainty to be found in mathematics or logic but go on to argue that even the highly formal frameworks of math and logic do not necessarily offer that. In fact [Lewis, Gallant] conclude that the only scientific certainty is uncertainty.

Variables as sources of uncertainty

Uncertainty is inherent in the universe and found virtually in all sectors of life. It also increases with more variables. As in the question above, even if you are quite certain that the event x will occur, its uncertainty increases with the introduction of another variable y(time). Such events are said to be imminent and embody an interplay of certainty and uncertainty. That is, we are sure that the event will occur but are uncertain at what time. This complication with the introduction of more variables is also demonstrated in the famous Uncertainty Principle, where Heisenberg asserts that the momentum and position of a particle cannot both be precisely determined. Taken alone, the momentum can be determined with good precision. The same also goes with the position. The uncertainty only increases when we try to determine both. And this is why in scientific calculations, some variables are made constant to reduce the uncertainty. We often see statements like “Take g, the acceleration due to gravity as 10 m/s”. This eliminates the need to worry about how g varies on different locations on Earth thereby reducing the uncertainty. But then, we have only improved the certainty in that calculation but in reality the uncertainty still remains the same.

Humans have developed probabilistic thinking to deal with the uncertainties of life. So even though we cannot say that we are absolutely certain that a particular event will occur, we can quantify our confidence in its occurrence. Hence, people can say that they are quite certain or very certain about an event. But none of these are absolute. So even when someone says “I am certain that event x will occur”, they just mean it has a very high probability of occurrence.

So, is uncertainty bad on its own? Let us find out in the following sections.

Uncertainty and Randomness

Having established that absolute certainty is rare due to the presence of variables, some of which are unknown, what can we say about absolute uncertainty? Can uncertainty in fact be absolute? Before attempting to answer this question, it is important to differentiate the absolute uncertainty in question here from the concept of absolute uncertainty calculated for measurements. By absolute uncertainty here, I mean a state of 0 certainty. One could say, a state of absolute randomness without any detectable patterns or laws governing the occurrence of the event. In a way uncertainty and randomness are actually tightly connected. [Lewis, Gallant] differentiate between tangible uncertainties with known unknowns where we know the variables that introduce uncertainties, say an unknown exact value of g as described above, and other uncertainties with unknown unknowns where we are not even aware of the variables introducing the uncertainties. The latter is what I consider to be equivalent to randomness. We say that something is random because we are uncertain of what causes its behaviour. But does that mean that it has no cause or not being influenced by any variables? I believe it is more of our lack of knowledge of those variables than the actual absence of the variables themselves.

So this reduces the question of does absolute uncertainty exist? to does absolute randomness exist? This is an age long question which people have tried to answer from different points of view in different fields - Quantum Mechanics, Probability, Informatics, Philosophy, etc. In a nutshell, no proof so far has been given of absolute randomness because such proof would on its own embody a myriad of uncertainties. Nevertheless, the property of randomness is quite important so computer scientists have tried to develop algorithms for simulating pseudorandomness like generating random numbers. Numbers so generated are used in cryptographic hash functions and many other places. Even though this looks like a truly random process, it is not and scientists are constantly in search of how to make these algorithms more random. The solution is to introduce more uncertainties but of course, the question is how?

So far, this is an area where having more uncertainty is an advantage so we can see that uncertainty can also be useful in some way.

Psychological Certainty

Now, let us look at how certainty and uncertainty affect people psychologically. Attitude certainty refers to the confidence a person has on his behaviours, opinions and beliefs. It has been suggested that attitude certainty can greatly influence how easily a person can be persuaded. According to [Tormala], people tend to act on their attitudes when they feel certain as opposed to uncertain. They think more deeply when they feel uncertain as opposed to certain. In other words, to restore their certainty, they tend to ponder more on the subject which can improve persuasion. So to persuade someone, it will help to make reference to their uncertainties. Though another great application of uncertainty, it can also be used in social engineering.


In conclusion, neither absolute certainty nor uncertainty exist (or at least have not been proven to). Nevertheless, the absence of absolute certainty does not discredit scientific theories as they are usually defined with conditions that decrease the uncertainties and are shown to hold with some degree of certainty. Also, uncertainty as evil as it may sound, is actually useful in some circumstances and applied in different areas.


[Wiener, Norbert] “Is Mathematical Certainty Absolute?” The Journal of Philosophy, Psychology and Scientific Methods, vol. 12, no. 21, 1915, pp. 568–574. JSTOR, www.jstor.org/stable/2012740.

[Lewis, Gallant] “In science, the only certainty is uncertainty” [Online]. Available: http://theconversation.com/in-science-the-only-certainty-is-uncertainty-17180 [Accessed: 16-Apr-2019].

[BibleStudySchools] “Certainty versus Uncertainty” [Online]. Available: https://www.biblestudytools.com/commentaries/revelation/related-topics/certainty-versus-uncertainty.html [Accessed: 16-Apr-2019].

[Tormala] “The role of certainty( and uncertainty) in attitudes and persuasion” Current Opinion in Psychology, vol.10, 2016 pp. 6-11.


Kenneth Nwafor is a data scientist and software developer with great experience in the tech industry. He loves to write about tech, science and life in general.