I will give a survey of how a number of logical frameworks that have evolved, in different contexts and for very different purposes, during the last 50 years, in some cases as multivalued extensions of first-order logic, in others to deal with specific classes of structures, yet in others as general settings for model-theoretic stability, and yet others as theoretical foundations for soft computing, lead to a single model-theoretic logic. I will then state a maximality result that characterizes this logic in terms of the omitting types theorem. This result is joint work with X. Caicedo.