Full Idea
Postulate a higher-order state of affairs, of all the states of affairs in which Theaetetus is involved. Is this not a good candidate for a truthmaker for the negative truth that 'Theaetetus is not flying'?
Gist of Idea
Negative truths have as truthmakers all states of affairs relevant to the truth
Source
David M. Armstrong (Truth and Truthmakers [2004], 05.2)
Book Reference
Armstrong,D.M.: 'Truth and Truthmakers' [CUP 2004], p.58
A Reaction
It certainly seems extravagant to need the whole universe to make true 'there are no lions in this room'. But for 'there are no unicorns' it is not clear which states of affairs unicorns are involved. (Armstrong is aware of this).