Scepticism is a way of looking at ourselves and the world we live in as a source of limited knowledge. But if those limits exist, where are they?

Scepticism is an attitude that treats every claim to truth as up for debate.

Religion, philosophy, science, history, psychology – generally, sceptics believe every source of knowledge has its limits, and it’s up to us to figure out what those are.

Sometimes confused with cynicism, a general suspicion of people and their motives, ethical scepticism is about questioning if something is right just because others say it is. If not, what will make it so?

Scepticism has played a crucial role in refining our basic understandings of ourselves and the world we live in. It is behind how we know everything is made of atoms, time isn’t linear, and that since Earth is a sphere, it’s quicker for planes to fly towards either pole instead of in a straight line.

Ancient ideas

In Ancient Greece, some sceptics went so far as to argue since nothing can claim truth it’s best to suspend judgement as long as possible. This enjoyed a revival in 17th century Europe, prompting one of the Western canon’s most famous philosophers, René Descartes, to mount a forceful critique. But before doing so, he wanted to argue for scepticism in as holistic a fashion as possible.

Descartes wanted to prove certain truths were innate and could not be contested. To do so, he started to pick out every claim to truth he could think of – including how we see the world – and challenge it.

For Descartes, perception was unreliable. You might think the world around you is real because you can experience it through your senses, but how do you know you’re not dreaming? After all, dreams certainly feel real when you’re in them. For a little modern twist, who’s to say you’re not a brain in a vat connected up to a supercomputer, living in a virtual reality uploaded into your buzzing synapses?

This line of thinking led Descartes to question his own existence. In the midst of a deeply valuable intellectual freak out, he eventually came to realise an irrefutable claim – his doubting proved he was thinking. From here, he deduced that ‘if I think’, then I exist.

“I think, therefore I am.”

It’s the quote you see plastered over t-shirts, mugs, and advertising for schools and universities. In Latin it reads, “Cogito ergo sum”.

Through a process of elimination, Descartes created a system of verifying truth claims through deduction and logic. He promoted this and quiet reflection as a way of living and came to be known as a rationalist.

The arrival of the empiricist

In the 18th century, a powerful case was made against rationalism by David Hume, an empiricist. Hume was sceptical of logical deduction’s ability to direct how people live and see the world. According to Hume, all claims to truth arise from experiences, custom and habit – not reason.



If we followed Descartes’ argument to its conclusion and assessed every single claim to truth logically, we wouldn’t be able to function. Navigating throughout the world requires a degree of trust based on past experiences. We don’t know for sure that the ground beneath us will stay solid. But considering it generally does, we trust (through inductive reasoning) that it will stay that way.

Hume argued memories and “passions” always, eventually, overrule reason. We are not what we think, but what we experience.

Perhaps you don’t question the nature of existence at the level of Descartes, but on some level, we are all sceptics. Scepticism is how we figure out who to confide in, what our triggers are, or if the next wellness fad is worth trying out. Acknowledging how powerful our habits and emotions are is key to recognising when we’re tempted to overlook the facts in favour of how something makes us feel.

But part of being a sceptic is knowing what argument will convince you. Otherwise, it can be tempting to reduce every claim to truth as a challenge to your personal autonomy.

Scepticism, in its best form, has opened up mind-boggling ways of thinking about ourselves and the world around us. Using it to be combative is a shortsighted and corrosive way to undermine the difficult task of living a well examined life.