PSA004: True Belief


According to the Justified True Belief account of knowledge (JTB), a person can only truly know something if they have a belief that is both justified and true (i.e., knowledge is justified true belief). This account was challenged by Gettier (1963), who argued that JTB does not explain knowledge attributions in certain situations, later called Gettier-type cases, wherein a protagonist is justified in believing something to be true but their belief was only correct due to luck. Lay people may not attribute knowledge to protagonists with justified but only luckily true beliefs. While some research has found evidence for these so-called Gettier intuitions (e.g., Machery et al., 2017a), Turri et al. (2015) found that participants attributed knowledge in Gettier-type cases at rates similar to cases of justified true belief. In a large-scale, cross-cultural conceptual replication of Turri and colleagues’ (2015) Experiment 1 (N = 4724), we failed to replicate this null result using a within-subjects design and three vignettes across 19 geopolitical regions. Instead, participants demonstrated Gettier intuitions; they were 1.86 times more likely to attribute knowledge to protagonists in standard cases of justified true belief than to protagonists in Gettier-type cases. These results suggest that Gettier intuitions may be common across different scenarios and cultural contexts. When assessing the knowledge of others, lay people may rely on a shared set of epistemic intuitions (i.e., a core folk epistemology) that requires more than simply justification, belief, and truth. However, the size of the Gettier intuition effect did vary by vignette, and the Turri et al. (2015) vignette produced the smallest effect. Thus, epistemic intuitions may also depend on contextual factors unrelated to the criteria of knowledge, such as the characteristics of the protagonist being evaluated.


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