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The instrument that felt distant earthquakes

From East Asia·An enduring case

Zhang Heng's second-century seismoscope reportedly indicated an earthquake in a distant province before messengers arrived to confirm it, using a mechanism whose workings remain debated. The device detected reliably without its users holding a correct theory of why. Detection ran ahead of explanation by centuries.

The concepts this raises

Each of these gives a class a different way into the same case.

EvidenceGrounds of Knowledge
What is offered in support of a claim. Evidence is not the same as proof: it raises or lowers how likely a claim is, and its force depends on how it was gathered, what it was gathered for, and what else it is consistent with. Asking what would count as evidence against a claim is usually more revealing than listing evidence for it.
ExplanationGrounds of Knowledge
An account of why something is the case rather than merely that it is. Explanations are judged by more than accuracy: scope, simplicity, fruitfulness and the ability to say what would have happened otherwise all matter, and these criteria can pull against one another.

Where it sits in the knowledge framework

Methods and tools
The practices, conventions, instruments and forms of reasoning through which knowledge here is actually made, together with the assumptions those methods build in and what they are structurally unable to detect.

Areas of knowledge

The same ideas, somewhere else

Cases that raise a concept this one raises, but in a different area of knowledge or a different part of the world. That contrast is the point: it is what shows a student the concept travels.