In The dialectic of ambiguity (Van Laar 2003) he develops a formal model for critical discussion that is suited for analysing and evaluating arguments that contain actively (or problematically) ambiguous expressions. According to the definition developed in the project, an actively ambiguous expression admits of several readings within the context in which it is put to use. In addition, an expression is only actively ambiguous if neglecting the distinction between its readings has certain consequences for the course of the dialogue. It is explained how this kind of ambiguity may underlie various kinds of misunderstanding (such as pseudo-agreement or pseudodisagreement) and equivocation (a faulty kind of reasoning in discussion).
The model explicates the concept of 'dispute resolution' in those situations where one of the discussants supposes an expression to be actively ambiguous. The discussion rules enable the parties to raise the charge that the other party has committed the fallacy of ambiguity. In addition the rules regulate rights and obligations that apply to a metadiscussion where the parties are arguing about such a fallacy criticism in a reasonable and critical manner.
The model is applied to a cross-examination in a trial against American tobacco companies, and to a debate in Dutch parliament about the bill termination of life on request. That resulted in detailed assessments of dialogues in which the active ambiguity of formulations played a role.