Two approaches to the analysis of tags

In recent literature on transformational grammar there has been a good deal of discussion of tag sentences (Klima, 1964; Katz and Postal, 1964; Bolinger, 1967; Arbini, 1969). The type of construction under consideration is exemplified in the following (incomplete) paradigm: (1) John has gone, hasn't he? (2) John hasn't gone, has he? (3) John has gone, has he (?) (4) John hasn't gone, hasn't he (?) (5) Come early, won't you (?) (6) Come early, will you (?)