Philosophers Series · Part 1 of 12

David Deutsch: Depth Is Winning – Just Not Yet in What We Know About Ourselves

Last updated: 2026-09-26 · 5 min. read

The physicist David Deutsch says our knowledge is growing not only broader but, above all, deeper. When it comes to knowledge about individual human beings, the opposite has been true so far. Part 1 of our Philosophers Series asks why – and what we can already do about it today.

Broader and deeper

David Deutsch works at Oxford and is often called one of the fathers of quantum computing. In “The Fabric of Reality” (1997) he describes how knowledge grows. For him, knowledge consists mainly of explanations, not facts – facts can be looked up. With every better theory, our knowledge becomes broader, as new fields emerge, and deeper, as fundamental theories explain more and more. He sums it up in three words: “Depth is winning.”

For people, breadth is winning

Apply this idea to what humanity knows about individual people, and the picture changes.

According to estimates by the Population Reference Bureau, around 117 billion people have ever been born. About 8 billion are alive today – just under 7 percent. Every generation adds more names, more photos, more data points. Our knowledge about people keeps getting broader.

But it doesn’t get deeper. Why someone made the choices they did, what they believed, feared and learned – these explanations disappear with almost every death. We know that roughly 109 billion people lived before us. Why they lived the way they did, we almost never know. Most of us don’t even know the inner lives of our grandparents.

In Deutsch’s terms: we collect facts about people, but we lose their explanations.

Knowledge needs no knower

Deutsch has a remarkable definition of knowledge. In “The Beginning of Infinity” (2011) he describes it as information which, once physically embodied in a suitable environment, tends to cause itself to remain so. Following the philosopher Karl Popper, he stresses that knowledge does not need anyone to be knowing it at the moment. A book contains knowledge even if nobody is reading it.

That has a very concrete consequence. What a person has understood can outlive them – but only if it is embodied somewhere. Thoughts that exist only in someone’s head end with them. Written explanations can remain, be read, questioned and built upon.

Problems are soluble – forgetting included

“The Beginning of Infinity” carries an optimistic message: problems are inevitable, but problems are soluble. Humanity is not at the end but at the beginning. Towards the end of the book, Deutsch even suggests that illness and old age will be cured within the next few lifetimes, and that technology could create backups of the states of brains.

Whether and when that will happen is an open question, and many experts are far more skeptical. But in Deutsch’s logic, forgetting people is exactly that: a problem. And problems are soluble.

The transition period

Big advances almost always come with a transition period in which people do by hand what will later happen automatically. And that manual work often becomes the foundation.

There isn’t a single recording of Johann Sebastian Bach’s music from his lifetime – the technology arrived more than a century after his death. Yet we know his music, because it was written down in notation. Notation was the tool of the transition, and it was good enough to carry music through centuries until recording became possible. It never became obsolete: orchestras still play from the score.

When it comes to preserving people, we are at a similar point. Even if backing up a mind becomes possible one day, it won’t help anyone who lived before. Until then, everyone has to record for themselves what should remain.

Perrenix: a tool for depth that works today

This is where Perrenix comes in. Not as a concept for the future, but as a tool that works now. Every day you answer a question in your own words. Over months and years, what emerges is not a résumé or a photo collection, but the thing that usually gets lost: your explanations. Why you decided what you decided, what you believe, what you have learned. And you decide who can read it, and when.

It is notation for a life. Nobody knows today how future technology might one day use such records. Only two things are certain: no technology can recover what was never recorded. And any form of preservation still to come will depend on exactly what you can start building today – a deep record of your own thinking, grown over years.

The logical conclusion

Depth can only come from within. Others can collect facts about you. Only you can write down your explanations.

We are early. We are the first generation in which anyone can create a deep record of themselves with little effort.

The transition is now. Waiting for the perfect technology means losing the years in which you could have recorded what makes you who you are.

Three questions to think further

  1. Which decision in your life could no one but you explain later?
  2. What do you know about the inner lives of your grandparents – and what don’t you know?
  3. Which explanation about yourself should still exist a hundred years from now?

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