Is it Possible to Know Things With Absolute Certainty?

You might have heard the saying that the only things in life that are certain are death and taxes. However, what are you really wondering when you ask “What can we know for certain?”

Surely, it isn’t just about paying your tax bill, or knowing that life on earth is limited. Do we even know that for certain? It might be true at this moment, but who knows what kind of medical advances or sci-fi movie-worthy gadgets of the future could do to the human lifespan?

By Danielle Dahl, Lead Contributor
Writer, Entrepreneur and Inspirational quote curator 


We go through life with a series of projections, predictions, and assumptions thinking we know things for certain, only for them to be wrong. This can leave us shaken and floundering with what to do next. Let’s look at the argument for both sides, before trying to answer the question.

The argument for knowing things for certain

People who think there are things we can know for certain will use a series of arguments based on logic and deductive reasoning.

Is it Possible to Know Things With Absolute Certainty

One of the most popular arguments I have seen is that 1+1=2. We know that because we have been taught it and because we all agree on what those symbols represent. Math uses a self-consistent model, that everyone agrees upon so 1+1=2, would be a fact that people would say you could know for certain.

Then there is the concept of deductive reasoning. This states that if “A” is true and “B” is true then the conclusion must logically also be true. Let’s say “A” states that all people are mortal. “B” states that you are a person. If “A” is true and “B” is true, then you should know for certain that you are mortal.

When you use this theory it would seem like there are in fact things you could know for certainty. However, the flip side of this argument is how do we really know any of that is true?

“The two operations of our understanding, intuition and deduction, on which alone we have said we must rely in the acquisition of knowledge.”— Rene Descartes

The argument for thinking everything is uncertain

Descartes attempted to answer the question of what we can know for certain in his book, Meditations on First Philosophy. This book is such an interesting read, and if you are curious about the philosophy of certainty, then you should definitely read it. 

The book comprises six meditations. Descartes first discards all belief in things that are not absolutely certain and then tries to establish what can be known for sure. He wrote the meditations as if he had meditated for six days: each meditation refers to the last one as “yesterday”.

During the meditations, Descartes discards his beliefs in everything, leading him to wonder if he himself even exists. Imagine thinking that you aren’t certain if you are even real. Ultimately, he decided that “I think therefore I am.” This leads to the few things I think we can all be certain of.

“If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.” — Rene Descartes

You can always count on yourself and be who you truly are

Maybe you can’t count on the love of the people who should love you, like your parents, siblings, or significant others. Not all parents are loving and some even leave and abandon their children.

Siblings are not always best friends with each other. Sometimes, we enter into romantic relationships that are toxic and end up being abusive. However, one thing I have come to know for certain is that I can count on myself and the things that make me… well, me.

For me, that is resilience and kindness. Whenever life hits me with a challenge, I am certain that I will be alright, and able to come up with some kind of solution. Sure, it is not always the most optimal solution, but I work with what I have got. If it seems like I don’t have anything to work with, then I create something.

I try my best to be kind to everyone. Each of us is likely going through something at any given time, and I don’t like to make things worse for people. I try to be helpful whenever it is in my power to do something for someone else. 

My therapist would say I need to learn when to say “no” to people, but I don’t like to say no if I can help it. She is likely right, and I could use a few more boundaries, but what I am certain of, is that helping people makes me feel better.

The same can be said about love. You might not be absolutely certain of another person’s feelings and behaviors, but you can choose to love honestly and wholeheartedly, despite the potential pain.

As humans, we can’t even be certain that the authentic feelings we might have one day would be the same later on. Things happen, people change, but if you are honest, then you can always be certain that you will be true.

What are some of the qualities that you can always count on? “You think, therefore you are.” Who are you and what do you think?

I am certain that life is always too short

One could argue that we aren’t really sure if all humans are mortal, but for sake of this argument let’s err on the side of deductive reasoning and assume that people are indeed mortal. That means that you will encounter the death of someone you care about.

There will always be a part of you that feels like they were gone too soon. As your life moves on, it is hard to remember lost loved ones and think about what they are missing. Ultimately, though, you will also leave the world.

I am certain that there will always be more I want to do. More things I wish I could see. However, I am not certain how much time I have and neither is anyone else. Anything could happen at any time, and I choose to live life as if it is just too short.

Granted, I may not live “every day as if it is my last,” but I do try to keep in mind that tomorrow is not guaranteed. None of us can be certain just how many more tomorrows we have.

I am not certain of the time I have here on Earth, but I am certain that I can make the most out of the opportunities and lessons each day presents me with. I am a big fan of seizing the moments and taking chances.

At the end of the day, there isn’t much we can be certain of

There was a time that people were certain the earth was flat. Then science helped prove it is in fact round. I am certain the world is round, but what if I was to learn there are other things I believe that are just… wrong? What if 1+1 doesn’t equal 2? What if all the things we think are real, simply aren’t? No wonder it took Descartes years of pondering and meditation to dive down that rabbit hole!

Philosophical questions like “Is it possible to know things with absolute certainty,” are almost certainly going to leave you a little confused. At one point, after deducing that he did indeed exist, Descartes asked himself, “But what then am I? A thinking thing. And what is that?”

His answer was, “Something that doubts, understands, affirms, denies, wills, refuses, and also senses and has mental images.” You can be certain that you will have doubts about many things.

You will believe you have understanding and affirmations of what is true in this world. You might deny things that others are sure about. You have free will and the ability to refute information. You can use your senses and your thoughts to help you get through life.

If there is anything that I think we can believe for certainty, it is that life will always be filled with something unexpected. Something that makes us doubt and question who we are and what we believe. But we are “thinking things,” and have the ability to ask tough questions. So keep thinking and keep questioning. Share your thoughts in the comment section below, and let us know what you think about knowing things for certain.

“Except our own thoughts, there is nothing absolutely in our power.” — Rene Descartes