David Deutsch: some practical consequences...
Why am I so taken with David Deutsch? (See my earlier post for links )
Some people have commented that he is too abstract. I am a mathematician, so to me, abstract is a feature, not a bug.
But I’m also an engineer. And I am a citizen. And what he says has practical and civic implications.
According to one survey 65% of Americans think the world is getting worse. Another survey tells us that 57% of Americans think that our way of life will end in the next hundred years. 25% think we will go extinct. So we live in a country full of relatively hopeless, depressed people who differ in which catastrophe they think will destroy us (global warming, Islamic Jihadism, Ebola, Donald Trump).
Are we right to be so depressed? If not, what can we do about it? Deutsch states a principle that strikes me as an antidote—or at least an anodyne—for this depressed state. His explanation is an informal proof of the principle’s truth. He gives examples from human history to support his claim. (Although he would agree that examples prove nothing.)
Here’s the principle: Either a problem cannot be solved without violating the laws of the universe, or the problem can be solved—given the necessary knowledge. (Note that this does not mean you can solve it in a certain amount of time, or you can know how long it takes to solve it. It just says that you can, without question, solve it, given knowledge—or you’ve discovered a new law of the universe.)
His explanation: If you cannot solve a problem it cannot be that you didn’t have enough of some physical resource because you can always use knowledge to get more of any physical resource. There are only two remaining possibilities: either you do not yet have the knowledge (and once you have it, you will have the solution) or there is another law of the universe that was previously unknown that prevents you.
Therefore: all problems whose solutions do not violate the laws of the universe are solvable.
Take climate change as a practical example. Assume the dire scenarios are true. Assume that the cause is too much carbon dioxide in the atmosphere already, plus more going in every day. We can solve this.
There’s no law of nature that prevents us from pulling CO2 out of the atmosphere. Therefore we could do it, given enough knowledge. We know some ways to do this. Solutions include accelerating the growth of plants that sequester carbon, creating bacteria or plants that can do it, building devices that pull CO2 from air passed over them. What we don’t know is how to do them at a cost low enough to make them practical.
None of these solutions (and there are many others, not listed here) are held back by physical impossibility. None of them is even close to physical limits. We just don’t know how to do them cost-effectively. The difference between knowing how to do something and knowing how to do it affordability is—just knowledge. So we could do it if we knew.
There’s no law of nature that says we can’t cool the planet even before we remove the CO2. We know what some of these are. What we don’t know is how to scale these up; how to do them cost-effectively; we don’t know all the side effects, and we don’t know how to avoid the side-effects that we do know. But these are just knowledge problems.
But perhaps the knowledge we lack is unobtainable? Could that be true?
Yes, but only if we are attempting to gain a kind of knowledge that the laws of nature say that we cannot gain. We can’t know the future. We can make short term projections, but that’s it. But none of these problems requires us to know things that cannot be known.
Historically when humanity has faced terrible problems some people have argued: “We can’t solve that problem because fact X prevents us.” And historically we’ve often solved those problems by doing something that no one knew about—or even imagined—at the time; or because there was a way around fact X that was unknown and even unimagined at the time. Or because fact X was in fact, not a fact. Deutsch’s book is full of such examples.
“Fact” X wasn’t the barrier to solving the problem. Our lack of knowledge was. And our incorrect belief that X was a barrier. Once we removed the error or had the knowledge, we solved it.
But, you might say, the climate problem is not just technical. It’s a political problem, as well. We not only have to get the technical knowledge that we need, but we also have to convince people to act.
True: and why can’t we get people to act? Because we don’t know how to convince them. Knowledge again. We know vastly more about the way that humans organize themselves now than we did several hundred years ago. We are better at communicating and educating people. But we are not good enough. We need to get better still.
Some people believe that the problem of educating (other) people is unsolvable. (Of course, our own ideas are correct and don’t need to be changed.) But there is no law of nature that says we can’t solve this problem. Most people once believed angry gods caused weather; now few people in civilized society believe that. Humanity is educable. And we can do a better job of education with more knowledge about the way people think, the way that they change their minds, and so on.
Deutsch’s point—that we can solve all our problems given enough knowledge—is of practical import. There are areas where we could be doing research, and we are not—and if people could understand that one or more of these areas might give us a better answer, maybe they would act to support a solution.
Is there an error in this argument? Maybe, but I don’t think so.
Some people believe that when we solve one problem, we always produce another one, worse than the first. Examples abound. But is there a law of nature that says that problems must get worse? You can find many examples of solutions that led to bigger problems. But you can find many examples that led to smaller ones. I don’t think that anyone has proposed it’s a law of nature.
We face some big problems, but the problems that we now have—as human beings—are the result of our solving this problem: “How do I avoid a life that is nasty, brutish and short?” That is where we started out. People died young. Societies died out when the climate changed unexpectedly—because they had no knowledge of climate change. Or even when the weather changed! They died when disease struck, and they had no knowledge of how to prevent disease or to cure it. And they died when neighbors attacked because they did not know how to maintain a civilization without constant violence.
I would claim that global warming, ISIS, Ebola, Trump are lesser problems dying early from disease or violence—which until recently was the fate of almost all of our ancestors.
We can solve any problem, given knowledge. This is an optimistic stance, and I think that holding the optimistic stance has practical benefits. We don’t know how long it will take us to get the knowledge that we need. We don’t know how long it would take to solve the problem if we did have the knowledge today. We don’t know if we can gain the knowledge in time. We don’t know if some other problem will overtake us in the meantime.
We’re better off because we have some knowledge. And we need to get better still. If we fail to survive, it will be for one reason and one reason only: we did not know how to avoid whatever tragedy befell us.
We also know that we are creating knowledge faster than ever. The growth of knowledge is exponential. But is it fast enough? We don’t know.
So here’s the policy implication that can help us improve our chances: we need to work to create more knowledge. We need to invest in knowledge creation and to avoid policies that stand in the way of knowledge. We can help in small ways by educating ourselves and others. Who can tell what the effect will be?
There are people across the political spectrum who have forms of knowledge that they want to suppress. They argue that it’s too dangerous or destabilizing. But it’s ignorance that is dangerous, not knowledge.
Among the most valuable kind of knowledge is epistemological: on what basis do we judge knowledge claims. Making such judgments is not just restricted to science because not all knowledge is scientific knowledge. Deutsch has something to offer on this subject, and what he has said has changed my beliefs about several issues.
Most important, it’s changed some of my beliefs about belief.
I’ll write about these topics next.