Hume noticed in 1740 that arguments about morality slide, without warning, from sentences about what is to sentences about what ought to be. Build an argument here by switching premises on and off, and watch whether it can actually reach its conclusion. The bridge only spans the gap when a value premise is out in the open where someone can challenge it.
1 · Pick a live argument
2 · Switch premises on and off
Does the argument cross?
Nothing selected yetTurn on a premise or two on the left.
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Fact premises
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Value premises
Everyday leaps — tap to expose the hidden premise
Hume’s law is not anti-evidence. It says facts are necessary but never sufficient. Its practical use is to make people state the value premise they were hiding — because a hidden premise cannot be argued with.