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Here's a brain teaser: is there a limit to what we can know? Scientists say they know so

"It could be that the very deep elements of reality, which are as far beyond our grasp as quantum theory is beyond a monkey's grasp."
Is there a limit to what humans can know?
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Here's a mindbender for you: how do we know what we know? And how do we know that we, in fact, know it? And will there ever come a time where we reach the limits of what we can know?

If your head is spinning, read on. We asked two scientists about whether there's a limit to human knowledge — and whether we need to enlist the help of technology to move ourselves along.

We've only got a certain life span. We're going to die, and we think pretty slowly ... We can't just abstract away from all of those limitations and say everything is going to be knowable.- Jennifer  Nagel , associate professor of philosophy at the University of Toronto

"I'm sure there's a limit to what humans can know, and it could be that the very deep elements of reality, which are as far beyond our grasp as quantum theory is beyond a monkey's grasp," says Martin Rees, the United Kingdom's Astronomer Royal. "I really think that's possible." 

In his book "The Beginning of Infinity," quantum physicist David Deutsch defends the infinite possibilities of human achievement.

Rees says while we haven't reached the limits of knowledge, "there are almost certainly severe limits, because we know that our brains think about a million times slower than even a small computer. We know already that we have machines that are better than us... and there are certainly going to be limits to the sort of wet hardware inside our skulls."

But David Deutsch disagrees that there can be such a limit to how much knowledge we can take on. He's a visiting professor at the Centre for Quantum Computation at  the Clarendon Laboratory of physics at the University of Oxford, and is considered by many to be the father of quantum computing.

"There are things that are unknowable... but I don't think there can be anything interesting...that is unknowable. That idea is very akin to a belief in the supernatural." 



Martin Rees compares our relationship with knowledge to monkeys trying to understand Darwinism. David Deutsch says that essentially, a "human brain is like a monkey brain with add-ons." He says there isn't much difference between how a human and monkey brain compute information.

Knowing, understanding and believing something to be true may be the domain of science. But thinking about what it means to know something often falls to the philosophers — epistemologists, to be precise. Jennifer Nagel is an associate professor of philosophy at the University of Toronto, and the author of Knowledge: A Very Short Introduction.

"We've only got a certain life span. We're going to die, and we think pretty slowly," she says. "We can't just abstract away from all of those limitations and say everything is going to be knowable."

"We've only got a finite time here, even our computers only have a finite time here. It's perfectly possible that there could be interesting problems which can't be solved by any variety of available means in the time that we and computer friends have got."


Listen to the full conversation at the top of this post. 

This segment was produced by The Current's Karin Marley and Pacinthe Mattar.