It has taken humans a surprisingly long time to get better at knowing things. It's really important. And today it's even more important because social media's engagement algorithms show us whatever will keep us engaged, and so we end up living deeper and deeper in divided worldviews, unable to agree about reality.
Since Plato (who died in about 347 BC), we have thought about knowledge as justified true belief.
"Belief" is simple: If we don't believe something, we never think of it as something we know.
"True" takes us forward a thousand years to René Descartes (1596–1650). He famously said "cogito, ergo sum," which means, "I think, therefore I am." I don't always know whether I am awake or dreaming. I can't be certain what is real. The only thing that I can know for certain is true is that I am having a conscious experience.
If we believe something, and we have solid reasons for believing it, but it's not true, then we don't actually know it. We just think we know it. So "true" is just a placeholder: The only thing I know is true is that I am conscious.
That puts all the emphasis on "justified".
Science is the name we give to the methods that we use for justifying what we believe (and ideas that we don't believe, but want to check). Science works by testing beliefs against reality and checking whether other people get the same results. We have been improving these methods for centuries: We check more things. We check things more thoroughly. And there is still a lot that we can improve on.
Nobody is able to check everything themselves. That would be impossible. Instead, we trust people.
The first people we trust are our parents. But my parents didn't run randomized control trials on all of the medicine they gave me before giving it to me. No, they trusted the pharmacist and the doctor. And the pharmacist and the doctor trusted professors and medical journals reviewed by scientists.
There is a very important difference between a child and a scientist when it comes to the networks of people they trust:
Kids trust authority figures, like their parents.
Scientists trust experts, like other scientists who know more about a specific topic than they do.
Can authority figures be wrong? All the time.
Can experts be wrong? Sometimes, of course! But they are wrong much less of the time. That's what makes them experts.
Some experts are authority figures. Not all authority figures are experts.
Warning
Trust people who are experts rather than people who are only authority figures. And don't just people who say they are experts; trust people who scientists say are experts, because scientists understand that thinking you know something is not the same as actually knowing something.
Pierre de Fermat (1601–1665) and Blaise Pascal (1623–1662) founded probability theory when they wrote to each other about gambling. We never have all the justification we need to be certain about anything. It is important to understand and toacknowledge that everything we think we know, we really, honestly, can only have degrees of certainty about.
Religion is something that many people feel certain about. Here are the numbers from 2020 of people grouped by the religion that they say they hold to1:
| Religion | Believers |
|---|---|
| Christians | 2,300,000,000 |
| Muslims | 2,000,000,000 |
| Hindus | 1,200,000,000 |
| Buddhists | 320,000,000 |
| Jews | 15,000,000 |
| Other | 170,000,000 |
| No religion | 1,900,000,000 |
The believers of any religion are vastly outnumbered by those who don't hold to that religion. Every religion makes claims about reality that their believers think have sufficient justification, but non-believers of that religion don't think that.
Some believers of each religion describe what are regarded as religious experiences. Experience is what they consider to be the justification for the truth of their religion.
If you have dreamt, then you know that some experiences come from outside your head, and some come from inside. It is possible that what some, maybe even all, believers experience is something that human minds are capable of, rather than something happening externally. Maybe religious experience is an experience of our shared nature.
Religion is more than just a set of claims about reality. It is a family, a tribe. There are other tribes that also come with a set of beliefs and values: political parties; football clubs; sometimes companies and societies.
We take these on as a source of our identity -- we accept the tribes that we are born into, and that we choose, as who we are. We feel a powerful sense of loyalty towards them.
If we are to check the claims that they make, it's very difficult if we feel loyal to those ideas, or if our membership of our community or our family depends on accepting those claims as true.
If we want to believe true things, sometimes we need to let go of those identites first, so that we can evaluate not only the evidence that supports those claims, but honestly evaluate the evidence against those claims as well.
Bayesian inference is a method of working out the probability of an idea (a "hypothesis") based on a previous estimate of its probability and then updated with more evidence or data. This method is based on a theorem developed by Thomas Bayes(1701–1761), and also by Pierre-Simon Laplace(1749–1827). It's used in nature, including inside the human brain, to predict outcomes.
When we discover more information about a belief that we hold, we should re-evaluate it -- not throw it away, nor defend it -- but update our estimate of how likely it is to be true now that we know more.
For example, if you believe there's a 50% chance it will rain and then you see dark clouds, you update that to 70%.
Do the best you can until you know better. Then when you know better, do better. ― Maya Angelou
Perhaps the biggest challenge that we face in the 21st century is where we get our information from.
Are our sources of information reliable?
Some sources of information will publish retractions and corrections when they get things wrong. Other sources of information will do no such thing. Checking your work is expensive. And many people think that acknowledging when you are wrong reduces your credibility, so they don't do it. Also, it ruins their vibe. Sources of information like this are never to be trusted.
And what perspective do our sources see the world from?
Everyone sees the world from some perspective. Our perspective determines what we notice, and what we don't notice. All sources of information have a perspective. Some call it a bias, but "bias" has negative connotations. Some sources claim not to have a bias, but they still have to select what they think is important, and that is the result of one or more perspectives.
If you want to believe true things, you need your beliefs to be challenged, and that requires hearing perspectives that are not your own. But make sure those perspectives, the ones you share and the ones you don't, come from sources that acknowledge and correct their mistakes.
So far this has been about how we know facts. But it is also important to recognize stories. We tell stories about ourselves -- stories with elements that we recognize, and elements that we aspire to or strive for.
We know that Harry Potter isn't real. But we also know that Harry Potter is a wizard. He was protected by the love and sacrifice of his mother. And he overcame evil through both courage and the support of people who love him. Those are true things.
Humans love an answer. They absolutely adore an answer. They don't always like making sure that answer is correct.
That requires courage. And the support of people who love us helps a lot.
It is okay for true things to be stories rather than real.
It is also okay not to know whether something is true.
Sometimes believing things that are not true can be very helpful: I'm sure that believing in monsters that live in the water has saved countless children from drowning.
A lot of the time, it's harmless.
But sometimes the consequences are terrible and tragic: The measles vaccine does not cause autism, it saves people from dying of measles; None of the many covid vaccines contain microchips, and all of them prevent long covid, which is a life-changingly bad condition to have; Allah doesn't want anyone to fly airplanes into buildings, and there are no virgins waiting for anyone after they die.
All these are real examples of things that people have believed to be true -- bet their lives on -- with terrible and tragic consequences, and there are many more examples. I am hoping that what you have just read will help you to avoid tragedy in your own life and the lives of those you care about.