Group Deliberation and Evidential Dependency

In the recent debate on epistemic democratic decision-making, democratic deliberation and its epistemic qualities play a central role. Deliberation is an inherently serial procedure. It requires that individuals react to each other in turn, engaging in influencing each other's in- and outputs by asking for and providing justification. As such, it is opposed to most methods of voting, where all available evidence about individual preferences is gathered and aggregated simultaneously, optimally without one vote influencing another. Accordingly, it has been argued that deliberation is threatened by path dependency: Its outcomes are under risk of being arbitrary, based on the order in which individuals receive the inputs of their fellow reasoners and based on when it is their own turn to speak. If this result were to apply to democratic deliberation, it would call deliberation’s epistemic legitimacy into question. The procedure could not reliably contribute to finding an epistemically desirable outcome and instead be biased towards a limited set of evidence. I argue that the problem of path dependency can be mitigated by a feature that deliberation, as conceptualised in political theory, already possesses: the requirement of reason-giving. In particular, I show that path dependency occurs only if the participants in the discursive exchange fail to communicate their reasons for their conclusions and arguments at each stage of the deliberation. I introduce a formal model of informational exchange to clarify the discursive failures that lead to path dependency and show formally how reason-giving has to be understood in order to avoid these mistakes. Based on this, I develop a general account of how reason-giving can neutralise evidential dependencies between individual inputs, and present a general argument for deliberative reason-giving as an important tool in epistemic democratic decision-making.