Facts are easy. Giraffes have long necks. Eleven is a prime number. The Sun is a star.
But when faced with an opinion or assertion, I wonder where you fit along this scale.
If the answer is 'it depends', you're probably somewhere in the middle. I'm up the grey end.
Some people live very certain lives. They know what they like, they know what they believe, and they have very fixed views on right or wrong. Other people are less sure.
If you're trying to work out what to have for dinner or how to run the country, being a decisive person is a useful trait. But living in a black and white world can also have significant downsides, for example when judging others or making a decision with wider implications.
We draw conclusions about the world around us all the time. We react to items in the news, draw inferences from social media, interpret what others say and make assumptions about human behaviour. For some of us our reaction will be "I know what's going on here", while for others it's "I'm not so sure".
If you see someone reading a particular newspaper, for example, you may subconsciously jump to all sorts of conclusions about how they live and what they believe. "Typical Daily Mail reader," you might think, without stopping to consider that no such narrow archetype exists.
The accused looks guilty. Everyone knows the BBC is biased. My football team deserves to win. It's obvious how to vote. Everyone at TfL is incompetent. Some people know exactly what they think, in all kinds of situations, even when evidence is thin on the ground.
Certainty often results from not considering the wider picture. That amazing video someone retweeted into your timeline might be fake. Fixating on the colour of your passport is no guarantee of long-term economic success. Your newspaper might be convinced the storm of the century is coming, but did you think to check elsewhere?
Certainty also arises from shaky understanding of cause and effect. "Most coronavirus victims are Chinese" does not translate into "they look Chinese, they're probably infected". If the Chancellor is seen drinking one particular brand of tea, that's no reason to fervently boycott it.
Certainty sometimes derives from a narrow worldview. One source on the internet proves nothing. The Bible might not actually be true. You presume you know why that organisation made a 'bad' decision, but you don't really know why they did it because you weren't there at the time.
Certainty is seductively simple. The real world is messy and complex.
Scientists are trained to rely on hard evidence rather than a hunch. Mathematicians know the difference between proof and a flawed argument. Historians look for primary sources rather than secondary accounts, and even then take opinions with a pinch of salt. Our education system tries to make us question, hypothesise, even doubt, but still churns out citizens who rarely stop and think.
I prefer not to pre-judge, or at least I try to make a conscious effort not to. I don't always get it right, but I aim to remember that my first impulse might not always be correct. I can't just believe something, I like evidence. I'm aware that more than one factor might have been involved. I prefer 'might' to 'will', and 'could' to 'must'. I'm hardwired to see the world in shades of grey, not black and white.
I know I could be wrong. My trusted sources might not be entirely correct, and my assumptions might be embarrassingly inaccurate. But I am at least trying to consider all sides, even if my ambiguity doesn't always come across. It's good to have an element of circumspection about you, a recognition that what you think you've seen might not always be true.
Too much certainty can be dangerous. A mindset based on hunches and gut feelings is likely to be fundamentally flawed. A society founded on fixed opinions cannot react to changing circumstances. A world fed by lies presented as truth will end up stoking intolerance and dissent. The certain, I believe, are far more likely to be angry than the doubtful.
The world splits into people who think "definitely", people who think "probably" and people who think "maybe".