On the rationality of decision aiding processes

•Rationality is pivotal in Decision Aiding both as a science and a practice.•It plays a crucial role in determining its validity and legitimacy.•We use Habermas’ philosophy to clarify relevant conceptions of rationality.•We then distinguish objectivist, conformist, adjustive and reflexive approaches.•We explain how practitioners can identify which approach to implement in practice. The notion of rationality plays a crucial role in Decision Aiding (DA), both as a scientific discipline and as a professional practice. Indeed, a pervasive and possibly constitutive feature of DA is that it constantly faces challenges as to whether it is valid, legitimate, useful, practical, etc. Rationality plays a pivotal role in participating to determine whether DA fulfills such requirements. In this article, we take advantage of arguments developed in the philosophical literature, mainly by Habermas, to introduce a framework defining a series of conceptions of rationality. We use this framework in order to introduce a typology of DA approaches, distinguishing objectivist, conformist, adjustive and reflexive approaches. Whereas the underlying conception of rationality plays a key role in determining the features of DA processes, we argue that tools are largely independent of conceptions of rationality. Our reasoning has direct operational implications, which makes it of distinctive interest, not only for philosophers and operational research theoreticians, but also for practitioners. We explain how practitioners should reason in practice to identify which DA approach they should implement in a given situation. We then explain how they can take advantage of our analysis to entrench the legitimacy and validity of their recommendations.