Comment by acjohnson55

When the edges are numerous and blurry, you have to question the utility of trying to formalize a definition. Obviously, the idea of discrete languages is socially useful in many situations, but there's no point in trying to invent a hard rule to distinguish a dialect from a language. That's why it's better thought of as a continuum, with English vs Arabic being obviously distinct but recently divergent and convergent varieties left forever moot.