more on this theme | more from this thinker | more from this text
Full Idea
True statements about the necessary properties of things need not be necessarily true. The well-known example is that the number of planets (9) is necessarily an odd number. The necessity is de re, but not de dicto.
Clarification
'De re' refers to the thing itself, 'de dicto' to its description
Gist of Idea
Statements about necessities need not be necessarily true
Source
John L. Pollock (Epistemic Norms [1986], 'Nat.Internal')
Book Ref
'Epistemology - An Anthology', ed/tr. Sosa,E. /Kim,J. [Blackwell 2000], p.219
A Reaction
This would be a matter of the scope (the placing of the brackets) of the 'necessarily' operator in a formula. The quick course in modal logic should eradicate errors of this kind in your budding philosopher.