Notes for the Book: Deutsch on Reality

I’m still, intermittently, reading my way through David Deutsch’s The Fabric of Reality, and today came across these passages, that echo and underscore my thoughts in Notes for the Book: Hierarchy of Knowledge and Human Affairs. I said in that post the cumulative knowledge of hundreds and thousands of years of human investigation is in full view of anyone who cares to look. In books, at Wikipedia, in TED talks, etc etc.

Deutsch makes the crucial observation that the facts of the universe are visible right there in the universe itself, for anyone to see.

Page 95, recalling Galileo:

Every part of the Earth’s surface, on every clear night, for billions of years, has been deluged with evidence about the facts and laws of astronomy. For many other sciences evidence has similarly been on display, to be viewed more clearly in modern times by microscopes and other instruments. Where evidence is not already physically present, we can bring it into existence with devices such as lasers and pierced barriers — devices which it is open to anyone, anywhere and at any time, to build. And the evidence will be the same, regardless of who reveals it. The more fundamental a theory is, the more readily available is the evidence that bears upon it (those those who know how to look)…

The self-similarity of physical reality on several levels is what enables knowledge:

The very existence of general, explanatory theories implies that disparate objects and events are physically alike in some ways. The light reaching us from distant galaxies is, after all, only light, but it looks to us like galaxies. Thus reality contains not only evidence, but also the means (wuch 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. In those symbols — in our planetariums, books, films and computer memories, in our brains — there are images of physical reality at large, images not just of the appearance of objects, but of the structure of reality. There are laws and explanations, reductive and emergent. There are descriptions and explanations of the Big Bang and of subnuclear particles and processes; there are mathematical abstractions; fiction; art; morality; shadow photos; parallel universes. To the extent that these symbols, images and theories are true — that is, they resembles in appropriate respects the concrete or abstract things they refer to — their existence gives reality a new sort of self-similarity, the self-similarity we call knowledge.

(End of Chapter 4)

The universe is out there in plain view. Of course, most people are indifferent, and some people refuse to look, as did Church officials when Galileo offered to show them, in his telescope, the four moons orbiting Jupiter. Church officials knew such things couldn’t exist, because Scripture, and so refused to look.

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