In Defense of ‘Ought Implies Can’

Abstract

Two recent papers have presented experimental evidence against the hypothesis that there is a semantic connection between OUGHT and CAN, rather than a pragmatic and defeasible one. However, there are two flaws with their designs. One is temporal ambiguity: just asking whether “x ought to A” is underspecified as to when the obligation exists. Another is failing to distinguish between prior obligations and all-things-considered obligations. To test these potential confounds, the chapter author ran two experiments. The first paired some of the original stories with a visual timeline specifying the time of the obligation. The second flipped the wording of the original “obligated but can’t” question into the reversed: “can’t, but still obligated.” In both experiments, there were large and significant differences between the original and modified conditions. These results undermine the conclusions of the previous experiments and remain consistent with the Semantic Hypothesis.

Recent experimental work on “ought” implies “can”

“…There may also be a concern about study participants considering the moral obligation at a time other that which is specified by the experimenters (Cohen, ; Streumer, ). Leben () attacks earlier studies on these grounds and argues that temporal vagueness in the study designs led participants to make judgments inconsistent with OIC. To show this, Leben conducted an experiment in which Buckwalter and Turri's () vignettes were represented in a timeline diagram.…”

“…Notably, participants agreed with the “ought” statement at a significantly higher rate when it referred to a time before the inability compared to when it referred to a time after the inability. Leben concludes that ability influences “ought” judgments when time is explicitly stated (Leben, ).…”

“…For example, on this view, the sentence “A ought to X, but A cannot X” would be interpreted as “A had a previous obligation to X, but A is currently unable to X” instead of “A has a current obligation to X, but A is currently unable to X.” Leben again used Buckwalter and Turri's () materials with both the original and the reordered statements (for example, original: “Walter is obligated to pick up Brown at the airport, but Walter is not physically able to do so” and reordered: “Walter is not physically able to pick Brown up at the airport, but he is still obligated to do so”). The results of some of the scenarios show that when the original ordering was reversed, fewer participants chose the inability‐obligation response (Leben, ). These findings are consistent with those of Kurthy, Lawford‐Smith, and Sousa (), who similarly altered Buckwalter and Turri's () designs by changing the wording of the response options and found that people made fewer OIC violations.…”

“Must” implies “can”

“…Traditionally, this idea has been interpreted in terms of “ought” implying “can” (Moore, 1922). After many years of debate, it remains unclear whether “ought” does imply “can” (Kurthy et al, 2017; Leben, 2018; Streumer, 2019) or does not (Buckwalter & Turri, 2015; Henne et al, 2016; King, 2019).…”