Interrogatives and indefinites both involve a variable, as is the case, e.g., in Indo-European k(w)- words (English wh- words). Used interrogatively, they invite to substitute an appropriate constant to the variable; used indefinitely, they either retain the variable not quantified (in irrealis contexts), or combine it with a quantifier (existential, universal, "free choice", or negative). Latin typically illustrates this state of affairs: it crucially involves indefinite uses of the so-called "bare interrogatives" as irrealis markers (si quis ... 'if somebody/anybody ... '). French has only partially kept this heritage: it has no irrealis marker, and the links between interrogatives and indefinites are, at least apparently, loosened. On the whole, interrogative and indefinite markers are linked naturally, but not compulsorily: they can develop, at least partially, along different paths, -as in French.
