There are two kinds of logical errors. Either you use a non-valid scheme of an argument or your analysis of the premises is mistaken. No extensional or intensional theory can solve the following problem connected with analyzing NL expressions: The Leibniz principle of substituting identical for identical contains the condition a = b. Extensional as well as intensional systems (at least if intensions are defined as functions from possible worlds) analyzing this condition as formulated in natural language are happy if a is contingently or logically or analytically equivalent with b, while this may be insufficient for applying Leibniz. Examples are adduced that show the absurdity of applying Leibniz in such cases. A following remedy is thinkable: one could try to formulate some axioms or perhaps meta-formulated rules that would eliminate the critical cases. This would mean however that a new theory came into being just to shield us from incorrectly applying Leibniz rule. Instead a procedural analysis of NL expressions is offered that makes it possible to unambiguously determine their sense and so their denotation in such a way that the above mentioned critical cases cannot set in. It is shown that the hyperintensional system defined by Transparent intensional logic is able to generally solve the main problems connected with using NL expressions.