We argue that the epistemic modal 'might' is a generator of alternatives in the sense of Hamblin semantics (Kratzer & Shimoyama 2002) or inquisitive semantics (Ciardelli, Groenendijk & Roelofsen 2009). Building on methodologies from the psychology of reasoning, we show that 'might' patterns with disjunctions and with indefinites in giving rise to a particular kind of illusory inference. The best extant accounts of these illusory inferences crucially involve alternatives, paired with matching strategies (Walsh & Johnson-Laird 2004) or with question-answer dynamics (Koralus & Mascarenhas 2013). Our results constitute further steps toward convergence between theories and methodologies in natural language semantics and the psychology of reasoning.

In this paper, we employ an experimental paradigm using insights from the psychology of reasoning to investigate the question whether certain modals generate and draw attention to alternatives. The article extends and builds on the methodology and findings of Mascarenhas & Picat (2019). Based on experimental results, they argue that the English epistemic modal might raises alternatives. We apply the same methodology to the English modal allowed to to test different hypotheses regarding the involvement of alternatives in deontic modality. We find commonalities and differences between the two modals we tested. We discuss theoretical consequences for existing semantic analyses of these modals, and argue that reasoning tasks can serve as a diagnostic tool to discover which natural language expressions involve alternatives.