Informal Reasoning and Logical Formalization * 1. Introduction

In ever so many philosophical introductions to formal logic the latter is presented as the philosopher’s ars iudicandi, i.e. as the instrument that evaluates the quality of philosophical arguments or, more generally, of informal reasoning. Irrespective of its content, an argument is only worthy of consideration if it is valid, i.e. if the truth of its premise(s) necessitates the truth of its conclusion. As the validity of arguments hinges on the latter’s form, validity tests must be conducted by abstracting from the content of the argument. According to a prevalent conception of logic among philosophers, the instrument best suited for that task is formal logic. Philosophical arguments are commonly formulated in natural language. Thus, in order to put logical formalisms to work when it comes to evaluating the validity of philosophical arguments, natural language first must be translated into a suitable formalism. Such translations