Introduction Aldo Antonelli's untimely death is a sad loss to our profession. We have been asked by the editors of the Journal of Philosophical Logic to write a short comment on his most recent work, published in this issue, based in part on a referee report by one of us, that, unfortunately, did not reach Aldo in time.Here is what appeals to us in the innovative work in [4,5]. There is a long history of attempts to reanalyze the semantics of first-order predicate logic, the most basic system in our field. What many of these attempts have in common is a search for specific parameters in the 'standard semantics' given by Tarski that might be naturally modified or generalized. A further motive has been the issue whether the famous 'undecidability of predicate logic' is truly an intrinsic inescapable property of this system, or a side effect of decisions concerning its semantic design that could