What are the limits of science? Can it “explain” everything? Is all knowledge ultimately reducible to scientific knowledge?

These questions lie at the heart of many of the vexing issues facing human culture. Discussions of science and religion, the nature of consciousness, the role of the humanities, the existence and possible dangers of “scientism”—in some way, these all revolve around the question of science’s ultimate reach.

This issue is particularly important to me as a physicist who has long been interested the intersection of science and philosophy. And so today—in the first of a series of posts on this topic—I want to take on a specific question best identified via a famous quote from philosopher Ludwig Wittgenstein:

“Whereof one cannot speak, thereof one must be silent.”

This bit of text comes from Wittgenstein’s Tractatus Logico-Philosophicus (Latin for “Logico-Philosophical Treatise”), which concerns itself, among other things, with the relationship between language, logic, and reality. Wittgenstein was expressing the idea that the limits of language—and its underlying logic—exhaust what can be both experienced and discussed. If it can’t be expressed in language, then there’s nothing to say about it, because it couldn’t exist.

But later in life, Wittgenstein began to see language in a different light that colors this quote differently. Instead of language exhausting what can be experienced because of its logical structure and relation to reality, Wittgenstein came to see language as an organic construction in which the very human context of its creation and use was of central importance. In this way, his quote can be reinterpreted to mean there are aspects of experience that are real, but can’t be captured in language: hence the silence.

While I am still climbing up the Wittgenstein learning curve, this tension between the early and later versions of his views on language and reality capture something essential about our original question about the limits of science.

Science is an empirical method for developing explanations for phenomena we encounter in the world. Explanations are powerful things. They become most powerful for us when they include the capacity to make predictions. That’s what gives us the capacity to gain some control over the world.

“Explanatory predictions” let us tell when a hurricane is coming. Explanatory predictions also let us blend compounds together to create healing drugs. Ultimately, our concern with the question of science’s limits derives from the enormous power of its explanatory predictions. We see the advances in medicine, computers, aerospace technology, etc., and are rightfully awed by science’s capacities. It’s from that vantage point that we wonder about if it has any limits at all.

When language is insufficient

But what we can never forget is that science is itself embedded in language. Explanations can never transcend the words and equations used to create their frames. And, I will argue here and in forthcoming posts, language does not exhaust experience. In fact, experience must always overflow the capacity of language. This is what makes Wittgenstein’s “thereof one must be silent” such a potent formulation.

There is more to being than speaking.

So what exactly is meant by the word “experience”? It can be hard to drag experience as experience into the light since it’s so close to us that it’s easily missed. Experience is the common ground for all human beings. It’s what is meant by the ubiquitous but mysterious verb “to be.” Other words used for experience are “presence,” “being,” and “perception.”

Philosophers have even invented new words to get us to see experience for what it is. Edmund Husserl spoke of the lebenswelt (lifeworld) and Martin Heidegger referred to humans as dasein (the experience of being). I will likely spend a whole post unpacking these ideas about experience, but here I will take the following statement as a given:

Experience comes first. Language comes later.

For me, the truth of this statement bears directly on the question of science’s limits. It transforms that question into a new one about the limits of any form of explanation. Explanations, like science, are remarkable and powerful. But there is a way in which they will always come up short. They can never exhaust the world because the world—as experience—always contains more than words can express.

This is the lesson of poetry when it works at its most profound level, where words are used to point beyond themselves. This is also why, even though I’m an atheist, I take experiences of sacredness seriously (and wrote a whole book about it).

So the question is not, “Can science explain everything?”, but “Where do we place explanations themselves within the larger frame of experience?” That’s because no matter what we do, at some point we will have to face that silence beyond words. It could be a walk in the woods. It could be at the birth of our children. It could be at the death of a loved one. It will certainly be at the moment of our own deaths.

And when that moment comes, explanations will simply no longer be the point.

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Frank is a professor of astrophysics at the University of Rochester.