Full Idea
One person says 'He can't dig a hole; he hasn't got a spade', and another says 'He can dig a hole; just give him a spade', and both uses of the modal 'can' will be true. So some philosophers say that all modal predications are thus context-dependent.
Gist of Idea
A modal can reverse meaning if the context is seen differently, so maybe context is all?
Source
John Hawthorne (Three-Dimensionalism v Four-Dimensionalism [2008], 1.2)
Book Reference
'Contemporary Debates in Metaphysics', ed/tr. Sider/Hawthorne/Zimmerman [Blackwell 2008], p.266
A Reaction
Quine is the guru for this view of modality. Hawthorne's example seems to me to rely too much on the linguistic feature of contrasting 'can' and 'can't'. The underlying assertion in the propositions says something real about the possibilities.