Lessons from David Deutsch

On Knowledge and Explanation

On Good Explanations: "All progress, both theoretical and practical, has resulted from a single human activity: the quest for what I call good explanations." [1] Good explanations are difficult to vary while still accounting for the phenomena. [2]
The Nature of Scientific Theories: "The overwhelming majority of theories are rejected because they contain bad explanations, not because they fail experimental tests." [3][4]
The Growth of Knowledge: "The growth of knowledge is a continual transition from problems to better problems, rather than from problems to solutions or from theories to better theories." [5]
How Knowledge is Created: Knowledge doesn't come from induction or repeated observation. [6] It begins as a conjecture and is then refined through cycles of criticism and testing. [7]
The Uniqueness of Explanatory Knowledge: Humans are "universal explainers." [8] We don't just know facts (like the sky is blue), but we can understand the underlying explanations (why it's blue due to light scattering). [8]
The Fallibility of Knowledge: All of our knowledge is imperfect, but it can be improved through critical thinking and the process of identifying and correcting errors. [8] This is the concept of fallibilism. [8]
Error-Correction as the Key: "Without error-correction all information processing, and hence all knowledge-creation, is necessarily bounded. Error-correction is the beginning of infinity." [5][9]
The Reach of Explanations: "The theory reaches out, as it were, from its finite origins inside one brain...to infinity. This reach of explanations is another meaning of 'the beginning of infinity'." [10]
Creativity in Science: "Discovering a new explanation is inherently an act of creativity." [3][10] These ideas have to be guessed, not mechanically derived. [9]
Understanding vs. Programming: "If you can't program it, you haven't understood it." [3] This quote is from his book, The Beginning of Infinity. [3]
Science vs. Common Sense: "Our best theories are not only truer than common sense, they make more sense than common sense." [3][4]
The Aim of Science: "The ultimate goal of science is not just to explain the world, but to transform it." [11]
The Role of Questions: "Science is the best way to understand the world, not just because of its ability to provide answers, but because of its ability to ask the right questions." [11]
Objectivity of Knowledge: "Science is objective. And in my view we cannot take any experimental results seriously except in the light of good explanations of them." [10]
The Limits of Knowledge: "Nothing is unknowable – the limits of what we can know are defined by our current understanding, not by the nature of reality itself." [11] Deutsch argues there is no limit to the knowledge we can create. [12]

On Optimism and Problems

The Principle of Optimism: "Optimism is, in the first instance, a way of explaining failure, not prophesying success. It says that there is no fundamental barrier, no law of nature or supernatural decree, preventing progress." [5]
The Duty to be Optimistic: "We have a duty to be optimistic. Because the future is open, not predetermined and therefore cannot just be accepted: we are all responsible for what it holds. Thus it is our duty to fight for a better world." [13]
Problems are Solvable: "Every problem that is interesting is also soluble." [3][4] All evils are caused by a lack of knowledge. [14]
Problem-Fixing, Not Avoidance: "No precautions, and no precautionary principle, can avoid problems that we do not yet foresee. We need a stance of problem-fixing, not just problem-avoidance." [3][15]
The Nature of an Unproblematic State: "An unproblematic state is a state without creative thought. Its other name is death." [9][15]
Optimism and Civilization: "An optimistic civilization is open and not afraid to innovate, and is based on traditions of criticism." [5][15]
The Cost of Lost Optimism: "Like every other destruction of optimism...if any of those earlier experiments in optimism had succeeded, our species would be exploring the stars by now, and you and I would be immortal." [3][9]
The Rationality of Optimism: Rational optimism is key to unlocking our limitless potential. [16][17] Every transformation not forbidden by the laws of physics is achievable with the right knowledge. [14]
Wealth and Transformation: "Wealth is not a number... It is the set of all transformations that you are capable of bringing about." [2] Real wealth is the ability to transform the physical world. [16][17]
Preparing for the Future: To prepare for unforeseeable disasters, "we need rapid progress in science and technology and as much wealth as possible." [7]

On Reality and the Multiverse

The Quantum Multiverse: "The quantum theory of parallel universes is not the problem, it is the solution... It is the explanation - the only one that is tenable - of a remarkable and counter-intuitive reality." [3]
Quantum Computation and Parallel Universes: "Quantum computation is a distinctively new way of harnessing nature. It will be the first technology that allows useful tasks to be performed in collaboration between parallel universes." [3][4]
The Fabric of Reality: Reality can be understood through four interconnected strands: quantum physics (especially the multiverse), epistemology (theory of knowledge), theory of computation, and theory of evolution. [18][19]
Fiction vs. Fact: "All fiction that does not violate the laws of physics is fact." [9][15]
The Nature of Time: "We do not experience time flowing, or passing. What we experience are differences between our present perceptions and our present memories of past perceptions." [9] Quantum theory depicts time as consisting of distinct, co-existing universes, each representing a specific moment. [12]
The Universe as a Resource: "The universe is not there to overwhelm us; it is our home, and our resource. The bigger the better." [1][9]
The Finite is Parochial: "If you reject the infinite, you are stuck with the finite, and the finite is parochial... the best explanation of anything eventually involves universality, and therefore infinity." [3][15]
Objective Reality: "Reality is not determined by our beliefs – it exists independently of our understanding or perception of it." [11]
Time Travel: "I myself believe that there will one day be time travel because when we find that something isn't forbidden by the over-arching laws of physics we usually eventually find a technological way of doing it." [15]

On Human Significance and the Future

Human Cosmic Significance: "Humans may or may not have cosmic significance, and if they do, it will be by hitching a ride on the objective centrality of knowledge in the cosmic scheme of things." [3][4]
The Uniqueness of the Human Brain: "The brain is the only kind of object capable of understanding that the cosmos is even there, or why there are infinitely many prime numbers, or that apples fall because of the curvature of space-time, or that obeying its own inborn instincts can be morally wrong, or that it itself exists." [3][4]
Feeling Insignificant is a Mistake: "Feeling insignificant because the universe is large has exactly the same logic as feeling inadequate for not being a cow." [3][9]
Humans as a Spark: "Like an explosive awaiting a spark, unimaginably numerous environments in the universe are waiting out there... If we want to, we could be that spark." [5][7]
The Potential of Technology: "If something is permitted by the laws of physics, then the only thing that can prevent it from being technologically possible is not knowing how." [9][10]
Artificial General Intelligence (AGI): True AGI will require creativity and the ability to form explanations, not just execute a program. [2] This includes a form of "disobedience," a hallmark of human intelligence. [2]
Transmuting Elements: "Base metals can be transmuted into gold by stars, and by intelligent beings who understand the processes that power stars, but by nothing else in the universe." [5][15]
The Importance of Criticism: Open societies are crucial for progress because they are based on traditions of criticism, which allows for error correction. [5][20]
Judging Systems of Government: "Systems of government are to be judged not for their prophetic ability to choose and install good leaders and policies, but for their ability to remove bad ones that are already there." [9]
The Human Race as Universal Constructors: Deutsch poses the question, "Is the human race a universal constructor?" suggesting our potential to manipulate matter in any way the laws of physics allow. [4]
The History of Ideas: "History is the history of ideas, not of the mechanical effects of biogeography." [7]

Learnings and General Philosophy

Mistakes are Essential: Growth happens through trial and error. Every mistake is a learning opportunity that helps us find the right direction. [16][17]
Stay Endlessly Curious: One should never settle for shallow or incomplete answers and should keep digging until clarity is found. [16][17]
Ignore the Messenger, Focus on the Message: The truth of a statement is not dependent on who says it. [16][17]
Science Moves by Elimination: Science doesn't prove truths; it rules out falsehoods. Progress is the steady replacement of worse ideas with better ones. [16][17]
Choosing People Wisely: Avoid people with low energy, low integrity, and low intelligence, and seek out those who are high in all three. [16][17]

Learn more:

Lessons from David Deutsch

On Knowledge and Explanation

On Optimism and Problems

On Reality and the Multiverse

On Human Significance and the Future

Learnings and General Philosophy

Written by Antoine Buteau

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