Chapter VII addresses the issue of "Argument": "There is only one argument for doing something: the rest are arguments for doing nothing".
Cornford then expounds:
The Principle of the Dangerous Precedent is that you should not now do an admittedly right action for fear you, or your equally timid successors, should not have the courage to do right in some future case, which, ex hypothesi, is essentially different, but superficially resembles the present one. Every public action which is not customary, either is wrong, or, if it is right, is a dangerous precedent. It follows that nothing should ever be done for the first time.Should Cornford be required reading for archaeological ethicists and museum curators?