Q. Colleagues have asserted that the definite article is never used with a comparative and that the use of a definite article requires the superlative. Consequently, even in comparing two items, they’d use the superlative with the definite article: “That is the biggest house.” “That is a better car.” I’ve asserted that, in comparing only two items, one uses the comparative: “That is the bigger house.” “That is the better car.” Who is right?
A. There are two statements at issue: (1) that the definite article is never used with a comparative, which is wrong; (2) that when comparing only two items one uses the comparative, which is right—but not exclusively so. It’s idiomatic to use the superlative when comparing only two items. Sometimes forcing the comparative just makes you sound pedantic. You can read Grammar Girl on the subject here.