Maybe because I'm a mathematician my idea of "intuitive sense" is warped, but intuitively speaking, either John is in Paris or London exclusively. (This isn't given in the statement, but it holds intuitively.) Therefore, in the conclusion, we can assume that at least one of the antecedents "If John is in Paris..." or "If John is in London..." is false, and therefore at least one of the implications in the conclusion is true.