Full Idea
In Weak Kleene Logic, with truth-value gaps, a sentence is neither true nor false if one of its components lacks a truth value. A line of the truth table shows a gap if there is a gap anywhere in the line, and the other lines are classical.
Gist of Idea
In Weak Kleene logic there are 'gaps', neither true nor false if one component lacks a truth value
Source
Volker Halbach (Axiomatic Theories of Truth [2011], 18)
Book Reference
Halbach,Volker: 'Axiomatic Theories of Truth' [CUP 2011], p.263
A Reaction
This will presumably apply even if the connective is 'or', so a disjunction won't be true, even if one disjunct is true, when the other disjunct is unknown. 'Either 2+2=4 or Lot's wife was left-handed' sounds true to me. Odd.