Ladder
Cellular automata — the ladder
2 distinct arguments against one idea, from the one that introduces it to the one that assumes the rest.
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Eight rules and a triangle
A row of cells, each one deciding its next state from the three above it. Eight cases, one bit of output each — a rule that fits in a byte, and 256 of them in total. One of those bytes draws Pascal's triangle.
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The rule that computes
One of the 256 elementary rules can run any program. Not simulate one, not approximate one — a machine that can compute anything computable, built from a lookup table with eight rows and nothing else.