Certainty facts for kids

Certainty is when you are completely sure about something. It's a strong feeling that a belief is true, and you have no good reason to doubt it. Think of it like knowing for sure that the sun will rise tomorrow – you just don't question it.

Philosophers, who study how we know things, often talk about two kinds of certainty. One is objective certainty, which means a belief is true and can't be wrong, no matter who believes it. The other is subjective certainty, which is just how convinced *you* feel about something. You might feel totally sure about something, but that doesn't always mean it's objectively true or can't be proven wrong. Philosophers are mostly interested in whether anything can be objectively certain.

For a long time, people wondered if we could ever be truly certain about anything. Some thinkers, called skeptics, believe it's impossible to be certain about most things. They might say that even our experiences could be misleading. Today, many philosophers agree that most of our beliefs aren't perfectly certain and could be wrong. But some very basic ideas, like "I exist," are often still seen as certain.

What is Certainty?

Certainty is about having beliefs that you can't rationally doubt. It means you couldn't be mistaken in holding that belief. Another way to think about it is that certain beliefs are impossible to question, or they have the strongest possible reasons supporting them.

Certainty is closely linked to knowledge. However, many modern thinkers believe that to "know" something, you don't need to be as absolutely certain as you might think. For example, you can know that water is wet without needing to prove it beyond any possible doubt.

Being Sure in Different Ways

It's important to know the difference between being objectively certain and just feeling very convinced.

• Objective certainty (also called epistemic certainty): This is about whether a belief itself is true and can't be wrong. It means there are no good reasons for anyone to doubt it.
• Subjective certainty (also called psychological certainty or certitude): This is how strongly a person feels convinced that something is true. You might be 100% sure about something, but that doesn't mean it's actually true or impossible to prove wrong.

Philosophers are usually focused on whether any beliefs can reach that high level of objective certainty.

Ludwig Wittgenstein's Ideas

Ludwig Wittgenstein was a famous philosopher who wrote notes about certainty just before he died. His main idea was that the situation or context matters a lot when we talk about certainty.

He believed that while you can question almost any statement, certainty is still possible within a certain framework. He said that some ideas act like a "framework" that helps other ideas make sense. For example, we are certain that the ground beneath us is solid, and that certainty helps us understand how buildings stand up.

How Sure Can We Be?

We often talk about different levels of certainty. Not everything is a simple "yes" or "no" when it comes to how sure we are.

Physicist Lawrence M. Krauss has pointed out that it's important to know how certain we are about things, especially in science and when making big decisions. Different goals need different levels of certainty. For example, a doctor needs to be very certain about a diagnosis, but a weather forecaster might only be "mostly" certain about tomorrow's weather.

Measuring Certainty

Some people have tried to measure how certain we are.

• Rudolf Carnap thought certainty could be measured in degrees, with "one" being complete certainty.
• Bayesian analysis uses math to figure out how certain someone is, often seen as a measure of their personal belief.

Certainty in Law

In legal cases, there are different standards for how much evidence is needed to be "certain." These standards go from less certain to more certain:

• No credible evidence: There's nothing believable.
• Some credible evidence: There's a little bit of believable information.
• A preponderance of evidence: It's more likely than not (over 50% sure).
• Clear and convincing evidence: It's highly probable and not easily doubted.
• Beyond reasonable doubt: There's almost no doubt left, a very high level of certainty. This is usually needed for criminal convictions.
• Beyond any shadow of a doubt: This means absolutely no doubt at all. It's often seen as an impossible standard to reach.

If knowledge required absolute certainty, then it would be very hard to know anything at all, because most of our beliefs can be questioned in some way.

Certainty in Mathematics

Even in mathematics, where things seem very certain, there was a time in the early 1900s called the foundational crisis. This was when mathematicians were trying to find a perfect, unshakeable base for all of math.

They kept running into problems and puzzles that made it hard to prove that their systems were completely consistent (meaning they wouldn't lead to contradictions). It was a big debate!

Then, in 1931, a mathematician named Kurt Gödel proved something amazing. He showed that in any math system strong enough to do basic arithmetic, you could always find true statements that the system itself couldn't prove. He also showed that such a system couldn't prove its own consistency.

This meant that you can't reduce mathematical truth to just a set of formal rules, and you can't prove that all of math is perfectly consistent using math itself.

However, even with these discoveries, mathematicians are still very confident in their work. No major contradictions have ever been found in modern mathematics, despite how much it has grown. If a contradiction were found, most mathematicians believe they could fix it with small changes to the rules. So, while absolute certainty might be out of reach, there's a very high level of confidence in mathematical results today.

See also

• Almost surely
• Fideism
• Gut feeling
• Infallibility
• Justified true belief
• Instinct
• Pascal's Wager
• Pragmatism
• Scientific consensus
• Skeptical hypothesis
• Fallibilism (the idea that our beliefs might be wrong)
• Indeterminism
• Multiverse

Images for kids

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  A robot representing knowledge and certainty.