Is-ought
Also called: Naturalistic fallacy, Hume's guillotine
Moving from how things are to how they should be without saying why.
How to spot it
Does the argument slide from a fact to a duty with no moral premise in between?
Example
“People have always fought wars, so we ought to.”
How to answer it
Ask for the moral premise that links the fact to the “should”.
Related
- Appeal to nature: Claiming something is good because it is natural, or bad because it isn't.
- Appeal to tradition: Claiming something is right because it has long been done.