The fact that you can derive an ‘ought’ from an ‘is’ is manifestly wrong, just logically wrong. Facts in — facts out, values in — values out. By rules of deductive logic you can’t derive conclusions about properties that did not initially appear in your premises. Deriving an ‘ought’ from an ‘is’ is like adding two even numbers and obtaining an odd one. There is no description of the universe which contains oughts, descriptions of the universe only contain facts. So oughts stay on the one side, facts stay on the other. Right? Well, not so fast.

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David Hume, the guy who started it all


Even on Hume’s own terms, you can’t derive an ought from an is without making further assumptions. If you make further assumptions, you can derive as many oughts as you please. So, for example, you may find it reasonable to assume that you should avoid unnecessary pain. Granted this, you can then logically derive that you ought not stick your hands in boiling water without having a good reason for doing so. …


Valery Latyshev

Mathematician, philosopher, entrepreneur.

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