Full Idea
Putnam endorses the view that necessity is relative to a description, so there is only necessity 'de dicto': relative to language, not to reality.
Clarification
'De dicto' means concerning the words (not the things)
Gist of Idea
If necessity is always relative to a description in a language, then there is only 'de dicto' necessity
Source
report of Hilary Putnam (Reason, Truth and History [1981]) by Paul O'Grady - Relativism Ch.3
Book Reference
O'Grady,Paul: 'Relativism' [Acumen 2002], p.83
A Reaction
Even a realist must take this proposal seriously. The facts may contain de re necessities, but we could be very sceptical about our capacity to know them. Personally I enjoy speculating about de re necessities. They can't stop you.