David Deutsch
1953– · British physicist
Topics: learning, physics, mathematics, programming
Experience is indeed essential to science, but its role is different from that supposed by empiricism. It is not the source from which theories are derived. Its main use is to choose between theories that have already been guessed. That is what ‘learning from experience’ is.
— David DeutschMathematical knowledge may, just like our scientific knowledge, be deep and broad, it may be subtle and wonderfully explanatory, it may be uncontroversially accepted; but it cannot be certain.
— David DeutschA prediction, or any assertion, that cannot be defended might still be true, but an explanation that cannot be defended is not an explanation.
— David DeutschReality contains not only evidence, but also the means (such as our minds, and our artefacts) of understanding it. There are mathematical symbols in physical reality. The fact that it is we who put them there does not make them any less physical.
— David DeutschIf something is permitted by the laws of physics, then the only thing that can prevent it from being technologically possible is not knowing how.
— David DeutschOur best theories are not only truer than common sense, they make more sense than common sense...
— David DeutschIt is possible to build a virtual-reality generator whose repertoire includes every possible environment.
— David DeutschThe overwhelming majority of theories are rejected because they contain bad explanations, not because they fail experimental tests.
— David DeutschTo say that prediction is the purpose of a scientific theory is to confuse means with ends. It is like saying that the purpose of a spaceship is to burn fuel.
— David DeutschQuantum computation is … nothing less than a distinctly new way of harnessing nature … It will be the first technology that allows useful tasks to be performed in collaboration between parallel universes, and then sharing the results.
— David DeutschSince building a universal virtual-reality generator is physically possible, it must actually be built in some universes.
— David DeutschThe quantum theory of parallel universes is not the problem, it is the solution. It is not some troublesome, optional interpretation emerging from arcane theoretical considerations. It is the explanation—the only one that is tenable—of a remarkable and counter-intuitive reality.
— David DeutschSurely it is more interesting to argue about what the truth is, than about what some particular thinker, however great, did or did not think.
— David DeutschThe truly privileged theories are not the ones referring to any particular scale of size or complexity, nor the ones situated at any particular level of the predictive hierarchy—but the ones that contain the deepest explanations.
— David DeutschAny theory about improvement raises the question: how is the knowledge of how to make that improvement created? Was it already present at the outset? The theory that it was is creationism. Did it ‘just happen’? The theory that it did is spontaneous generation.
— David Deutsch