The Limitations of Human Knowledge — And Why That’s Not So Bad

While I am optimistic of humanity’s capacity to broaden its understanding of the universe — from cures to various diseases to the fundamental laws that underpin time and space — I accept and expect that there may always be limits to how much we can learn or solve. In a new book, What We Cannot Know, British mathematician and Oxford professor Marcus du Sautoy explores the limits of our species’ insatiable curiosity, as reviewed by The Economist:

One limit to people’s knowledge is practical. In theory, if you throw a die, Newton’s laws of motion make it possible to predict what number will come up. But the calculations are too long to be practicable. What is more, many natural systems, such as the weather, are “chaotic” or sensitive to small changes: a tiny nudge now can lead to vastly different behaviour later. Since people cannot measure with complete accuracy, they can’t forecast far into the future. The problem was memorably articulated by Edward Lorenz, an American scientist, in 1972 in a famous paper called “Does the Flap of a Butterfly’s Wings in Brazil Set Off a Tornado in Texas?”

Even if the future cannot be predicted, people can still hope to uncover the laws of physics. As Stephen Hawking wrote in his 1988 bestseller “A Brief History of Time”, “I still believe there are grounds for cautious optimism that we may be near the end of the search for the ultimate laws of nature.” But how can people know when they have got there? They have been wrong before: Lord Kelvin, a great physicist, confidently announced in 1900: “There is nothing new to be discovered in physics now.” Just a few years later, physics was upended by the new theories of relativity and quantum physics.

Quantum physics presents particular limits on human knowledge, as it suggests that there is a basic randomness or uncertainty in the universe. For example, electrons exist as a “wave function”, smeared out across space, and do not have a definite position until you observe them (which “collapses” the wave function). At the same time there seems to be an absolute limit on how much people can know. This is quantified by Heisenberg’s Uncertainty Principle, which says that there is a trade-off between knowing the position and momentum of a particle. So the more you know about where an electron is, the less you know about which way it is going. Even scientists find this weird. As Niels Bohr, a Danish physicist, said: “If quantum physics hasn’t profoundly shocked you, you haven’t understood it yet.”

Indeed, it sometimes feels as if we live in a post-science world, where objective scientific — and for that matter philosophical — truth just doesn’t exist. Expert consensus always appears to be shifting and overturning, studies constantly contradicting each other. People with completely different ideas on everything from economic policy to the existence of God will purportedly cite some sort of research, theory, or logical proof of their respective position. Not only is there a lot that we do not know, but even what we do know is often subject to different interpretations, and in some cases remains tentative.

Of course, none of this is to claim that there is no such thing as knowledge or objective truth. Expanding the limits of what we know necessarily means shaking up the status quo; most old ideas aren’t wholly overthrown so much as added to, tweaked, or redefined. The fact that science is always changing is actually evidence for its reliability: it fact-checks its own discoveries and sacred ideas, and challenges its own orthodoxies. The process of discovery is not always so clear cut or effortless — nothing involving our biased and flawed species is — but it’s the best one we got right now, and in the grand scheme of human history, it hasn’t been all that long since we devised a methodical approach to knowledge, so there is plenty of work left to do.

And fortunately, as du Sautoy points out, we nevertheless live in a “golden age of scientific knowledge” defineds by  “remarkable achievements stretch across the sciences, from the Large Hadron Collider and the sequencing of the human genome to the proof of Fermat’s Last Theorem” (I can’t even begin to go into what that last one is about.) Scientific publications have been doubling in number almost every decade since the 1940s, and that rate shows no sign of slowing down, especially as more and more countries develop the resources to invest in laboratories, institutes, observatories, academies, and education. Never have so many people had so many advanced tools and resources to pursue knowledge in one field or another.

Of course, there are plenty of issues regarding adequate public, political, and financial support of science, and no doubt these obstacles will exacerbate the above mentioned limits of human knowledge. But we must also look at how far we’ve come, and how much more we know and will continue to know with every passing week. I for one am excited for what is in store within my lifetime, and for how much good will hopefully come from all this expanded knowledge. I think the du Sautoy captures my optimistic sentiment precisely when he states, as told by The Economist:

There may be things people will never know, but they don’t know what they are. And ultimately, it is the desire to know the unknown that inspires humankind’s search for knowledge in the first place.

We mustn’t let the perfect be the enemy of the good. There might be a lot of holes in our knowledge, and a lot of knowledge we may never discover (or think to discover), but we shouldn’t let that lead to a distrust or cynicism about the limitations of progress. Otherwise, we wouldn’t have gotten this far in the first place.

I look forward to reading this book once it is published in the U.S. I have a feeling it is right up my alley!

What are your thoughts?

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