What You Achieve Depends on the Uncertainty You Tolerate: Stoicism in the Face of the Unknown
Introduction
In one of his letters, Seneca tells Lucilius about the death of an acquaintance, Cornelius Senecio. He was a hardworking, orderly man who had patiently built a fortune and had grand plans. One afternoon he visited a sick friend, ate dinner as usual, and died that very night. Seneca draws a lesson from the story: what madness it is to lay plans for many years ahead when we are not even masters of tomorrow.
The letter does not invite us to stop planning. It invites us to do something harder: to live and make decisions knowing that the future is not guaranteed—in other words, to tolerate uncertainty.
Total certainty does not exist. Whoever waits for it before acting waits forever.
This article explains why uncertainty causes so much anguish, what modern psychology says about intolerance of uncertainty, and what tools Stoicism offers for living with it.
Why Uncertainty Causes Anguish
The human mind seeks to predict. Knowing what will happen allows us to prepare, and not knowing triggers a natural alarm. That alarm is useful when there is a concrete danger, but it becomes a problem when it goes off in response to any open-ended situation: a job change, a new relationship, a medical test, a decision with no guaranteed answer.
Psychology has studied this trait under the name intolerance of uncertainty: the tendency to react negatively to uncertain situations, to experience them as threatening, and to seek certainty at any cost. Researcher Nicholas Carleton has proposed that fear of the unknown may be one of the core building blocks of many anxiety disorders.
The Cost of Seeking Certainty
People who cannot tolerate uncertainty tend to do things that, in the long run, make the problem worse:
- Postponing decisions until they have all the information—which never arrives.
- Avoiding change, even when the current situation is poor.
- Seeking constant reassurance: asking over and over, checking, double-checking.
- Worrying excessively, as if thinking through every possibility were a way of controlling it.
The result is usually a narrower life. The more certainty you demand, the fewer options remain. Any worthwhile change—whether a new job, a relationship, a project, or a habit—means stepping into unknown territory.
What the Stoics Propose
Distinguish What Is Up to You
Uncertainty usually refers to future outcomes, which are almost never entirely up to us. The dichotomy of control helps separate what is uncertain (the outcome) from what you can do today (preparation, action).
Plan with a Reserve Clause
The Stoics added "if nothing prevents it" when making plans. This reserve clause makes it possible to commit wholeheartedly to a project without demanding that the future conform to the plan.
Trust Your Own Tools
Marcus Aurelius left a note that is especially helpful for anxiety about the future: never let the future disturb you; you will meet it, if you have to, with the same weapons of reason which today arm you against the present. In other words, you do not need to solve tomorrow's problems today. When they arrive, you will face them with the same capacities you use to face today's.
Return to the Present
Seneca and Marcus Aurelius insist that we only ever live in the present. When uncertainty paralyzes you, a useful question is: what can I do right now, in this moment, to move closer to what I want?
Turning Fear into Curiosity
In Invicto, Marcos Vázquez suggests a shift in perspective: would you want to watch a movie if you already knew how it ended? Probably not. Uncertainty is also what makes life interesting. A completely predictable existence would be—besides impossible—rather boring.
This shift in perspective does not eliminate fear, but it adds something alongside it: curiosity about what might happen.
Decisions as Experiments
A practical way to live with uncertainty is to treat decisions as experiments. Instead of searching for the perfect decision, choose a reasonable option, test it for a set period, observe what happens, and adjust.
This attitude has several advantages:
- It reduces pressure. An experiment does not have to succeed; it just has to teach you something.
- It yields information. Action reveals things that analysis alone cannot anticipate.
- It allows course correction. If the experiment does not work, you change direction.
Not every decision lends itself to this approach—some are hard to reverse—but far more do than it first appears.
Common Mistakes
- Waiting until you feel sure before acting. Total certainty never arrives.
- Confusing planning with controlling. You can plan without expecting the future to obey.
- Thinking that tolerating uncertainty means not caring about anything. It means not letting worry make your decisions.
- Ignoring persistent anxiety. If intolerance of uncertainty interferes heavily with daily life, cognitive-behavioral therapy has specific treatments for it.
Conclusion
Seneca reminded us that no one owns tomorrow, and Marcus Aurelius that we will meet tomorrow with the same tools we use today. This week, pick one decision you have been putting off for lack of certainty and turn it into a small experiment: define what you will try, for how long, and what you will observe. When it ends, write down what you learned that you could not have known without trying.
References
- Seneca. Letters to Lucilius, 101.
- Marcus Aurelius. Meditations, VII.8.
- Epictetus. Enchiridion, 1.
- Carleton, R. N. (2016). Fear of the unknown: One fear to rule them all? Journal of Anxiety Disorders, 41, 5-21.
- Dugas, M. J. & Robichaud, M. (2007). Cognitive-Behavioral Treatment for Generalized Anxiety Disorder: From Science to Practice. Routledge.
- Vázquez, M. (2019). Invicto: Logra más. Sufre menos. Fitness Revolucionario.