Reasoning about epistemic possibilities.

Area of Science:

• Cognitive Psychology
• Formal Logic
• Decision Making

Background:

• Epistemic possibilities, crucial for daily reasoning, are traditionally formalized using modal logics based on possible worlds semantics.
• An alternative psychological theory suggests possibilities are based on constructing finite mental models.

Purpose of the Study:

• To investigate an alternative psychological theory of epistemic possibilities.
• To test predictions of this theory that diverge from standard modal logic.
• To challenge current conceptions of human reasoning.

Main Methods:

• Five experiments were conducted to test the predictions derived from the mental model theory of epistemic possibilities.
• Participants' reasoning patterns were analyzed in relation to modal logic principles.

Main Results:

• Experimental results corroborated the theory's predictions, showing that assertions of epistemic possibility presuppose the possibility of their negation.
• Reasoners were observed to condense multiple possibilities, resisting this condensation when it conflicted with knowledge.
• Epistemic possibilities were shown to function akin to non-numerical probabilities.

Conclusions:

• The findings challenge the sufficiency of traditional modal logic for explaining human epistemic reasoning.
• Human reasoning about possibilities is better understood through the lens of mental model construction.
• This research offers new insights into cognitive processes underlying judgment and decision-making.