Full Idea
Some nonclassical logic stays close to classical, assuming two mutually exclusive truth values T and F, but some sentences fail to have one. Others have further truth values such as 'half truth', or dialethists allow some T and F at the same time.
Gist of Idea
Nonclassical may accept T/F but deny applicability, or it may deny just T or F as well
Source
Leon Horsten (The Tarskian Turn [2011], 01.2)
Book Reference
Horsten,Leon: 'The Tarskian Turn' [MIT 2011], p.5
A Reaction
I take that to say that the first lot accept bivalence but reject excluded middle (allowing 'truth value gaps'), while the second lot reject both. Bivalence gives the values available, and excluded middle says what has them.
Related Idea
Idea 8709 The law of excluded middle is syntactic; it just says A or not-A, not whether they are true or false [Friend]