Does a Foreign Language Make Us More Rational, or Just Less Capable of Moral Thought?

For years, research has suggested that the language we use shapes the way we make moral decisions. The foreign-language effect, one of the most studied phenomena in this area, seems to show that when people face ethical dilemmas in a second language, they are more likely to choose utilitarian solutions, sacrificing one life to save five, for example, rather than adhering to rigid moral rules¹.

Take the Footbridge Dilemma, a variation of the well-known Trolley Problem. A runaway trolley is about to kill five people. You are standing on a footbridge above the tracks, next to a large stranger. The only way to stop the trolley is to push this person onto the tracks, where they will die but prevent the deaths of the five others. Most people, when asked this question in their native language, refuse to push the man. But when answering in a foreign language, they become significantly more willing to do so².

This effect has been consistently replicated. Costa et al. found that bilingual participants asked about this dilemma in a foreign language were more likely to endorse pushing the man than those answering in their native tongue³. Other studies confirm the same pattern⁴, suggesting that using a foreign language dampens our emotional responses, making us more detached and more rational in our moral decision-making⁵.

This would suggest that when we think in our mother tongue, emotional bias clouds our moral judgment, leading us to favor rigid, deontological rules, such as “never directly harm an innocent person,” even when breaking those rules would produce better overall outcomes. Since foreign languages are typically learned in academic or structured settings rather than in emotionally charged interactions, they supposedly create psychological distance from moral dilemmas, reducing gut-level aversion to causing harm⁶. Studies also indicate that people thinking in a second language take more calculated risks⁷ and make less emotionally driven financial decisions⁸, reinforcing the idea that language shifts our thinking from emotional to analytical.

The data supporting the foreign-language effect is robust. But what if the dominant interpretation is wrong?

I do not dispute the findings. People do make different moral decisions in a foreign language. But I challenge the idea that this shift reflects greater rationality or improved moral reasoning. Instead, I argue that this effect is better explained by cognitive strain and reduced expressive capacity, rather than by a clearer, more deliberate form of thinking.

Thinking in a Second Language Is Harder, and Moral Thought Suffers

Cognitive science provides overwhelming evidence that when mental effort increases, moral reasoning becomes weaker. Studies on cognitive load and ethical decision-making show that when people are mentally strained, whether due to fatigue, stress, or distractions, they default to simpler moral heuristics instead of engaging in deep ethical reflection⁹. If processing a foreign language increases cognitive effort, then the simplest explanation for the foreign-language effect is not that people become more rational, but that they default to moral shortcuts.

Consider the Footbridge Dilemma again. Utilitarianism provides the easiest possible rule: five lives over one. Sticking to deontological principles, the idea that some moral rules should never be violated, often requires complex justifications and nuanced argumentation. When people are mentally overloaded, they struggle to articulate their deeper moral intuitions and default to what is easiest to justify. In the case of a foreign language, this means relying on numerical logic rather than on moral instincts that are harder to express.

Language Is Not Just Communication, It’s a Tool for Thinking

Wittgenstein famously argued that “the limits of my language mean the limits of my world”¹⁰. If someone lacks fluency in a language, their ability to express and process complex moral reasoning in that language is diminished. Bilinguals frequently report feeling that they “lack the words” to fully express their thoughts in a second language, particularly when discussing abstract or emotionally complex topics¹¹.

This means that the foreign-language effect may not be a sign of increased rationality, but a symptom of moral impoverishment. If someone cannot articulate why something feels wrong, they might abandon their moral intuition entirely and settle for what is easiest to explain. In native-language reasoning, we have rich vocabularies of moral concepts, cultural references, emotional gradations, and ethical traditions. Without these linguistic resources, moral reasoning becomes thinner, shallower, and more transactional.

Emotions Are Not Biases, They Are Essential to Moral Thought

We should also ask whether emotional detachment really leads to better moral reasoning. While emotions are often framed as biases that distort rational judgment, moral psychology suggests they are essential to ethical thought¹². Studies strongly suggest that moral disgust, empathy, and intuitive aversion to harm play fundamental roles in shaping ethical decisions¹³. If a foreign language weakens these emotional responses, does that truly make us more rational? Or does it just make moral violations feel less significant?

Neuroscientist Antonio Damasio’s work on patients with damaged ventromedial prefrontal cortices, a brain region critical for emotional processing, reveals that these individuals make more "rational" choices in some contexts, but struggle profoundly with moral and social reasoning¹⁴. Their detachment from emotions does not make them moral exemplars; it makes them morally alienated. The foreign-language effect may create a form of artificial emotional distancing that mimics this deficit rather than enhancing true moral clarity.

A World Where Morality Is Simplified

If moral reasoning depends on cognitive resources, and using a foreign language depletes those resources, then moral decision-making will predictably shift, not necessarily toward better reasoning, but toward simpler reasoning. This interpretation better explains why the effect varies with language proficiency¹⁵, why it is strongest in high-conflict moral dilemmas¹⁶, and why it occurs in other cognitively demanding tasks, such as financial risk-taking¹⁷.

This insight extends beyond bilingualism. If moral reasoning deteriorates under cognitive strain, then modern life itself may be eroding ethical thought. In political institutions where discussions occur in non-native languages, such as the European Union or United Nations, moral deliberation may be biased toward simplistic, calculative reasoning rather than nuanced ethical engagement.

Morality is not just about what we believe. It is about our ability to think, express, and justify moral reasoning. When those tools weaken, so does our morality.

References

1. Costa A, Foucart A, Arnon I, Aparici M, Apesteguia J. Your morals depend on language. PLoS One. 2014;9(4):e94842. doi: 10.1371/journal.pone.0094842.
2. Geipel J, Hadjichristidis C, Surian L. How foreign language affects decisions: Rethinking the brain-drain model. J Int Bus Stud. 2017;48(5):645-51. doi: 10.1057/s41267-016-0040-1.
3. Cipolletti H, McFarlane S, Weissglass C. The moral foreign-language effect. J Multiling Multicult Dev. 2016;37(6):568-79. doi: DOI:10.1080/09515089.2014.993063.
4. Corey JD, Hayakawa S, Casasanto D. Rationalizing decisions in a foreign language. Psychol Sci. 2017;28(8):1196-1203. doi: 10.1177/0956797617720944.
5. Hayakawa SL, Tannenbaum D, Costa A, Corey JD, Keysar B. Thinking more or feeling less? Explaining the foreign-language effect on moral decision-making. Psychol Sci. 2017;28(9):1387-97. doi: 10.1177/0956797617720944.
6. Keysar B, Hayakawa SL, An SG. The foreign-language effect: Thinking in a foreign tongue reduces decision biases. Psychol Sci. 2012;23(6):661-8. doi: 10.1177/0956797611432178.
7. Costa A, Vives ML, Corey JD. On language processing shaping decision making. Curr Dir Psychol Sci. 2017;26(2):146-51. doi: 10.1177/0963721416680263.
8. Whitney P, Rinehart CA, Hinson JM. Framing effects under cognitive load: The role of working memory in risky decisions. Psychon Bull Rev. 2008;15(6):1179-84. doi: 10.3758/PBR.15.6.1179.
9. Wittgenstein L. Tractatus Logico-Philosophicus. London: Kegan Paul; 1922 [cited 2025 Mar 4]. Available from: https://www.gutenberg.org/files/5740/5740-pdf.pdf.
10. Dewaele JM. The emotional force of swearwords and taboo words in the speech of multilinguals. J Multiling Multicult Dev. 2004;25(2-3):204-22. doi: 10.1080/01434630408666529.
11. Greene JD, Haidt J. How (and where) does moral judgment work? Trends Cogn Sci. 2002;6(12):517-23. doi: 10.1016/S1364-6613(02)02011-9.
12. Prinz J. The emotional basis of moral judgments. Philos Explor. 2006;9(1):29-43. doi: 10.1080/13869790500492466.
13. Čavar F, Tytus AE. Moral judgement and foreign language effect: when the foreign language becomes the second language. J Multiling Multicult Dev. 2017;39(1):17-28. doi: 10.1080/01434632.2017.1304397.
14. Hennecke M, Freund AM. Age, action orientation, and self-regulation during the pursuit of a dieting goal. Appl Psychol Health Well Being. 2016;8(1):19-43. doi: 10.1111/aphw.12060.
15. Koenigs M, Young L, Adolphs R, Tranel D, Cushman F, Hauser M, et al. Damage to the prefrontal cortex increases utilitarian moral judgments. Nature. 2007;446(7138):908-11. doi: 10.1038/nature05631.
16. Greene JD, Morelli SA, Lowenberg K, Nystrom LE, Cohen JD. Cognitive load selectively interferes with utilitarian moral judgment. Cognition. 2008;107(3):1144-54. doi: 10.1016/j.cognition.2007.11.004.
17. Damasio AR. Descartes' Error: Emotion, Reason, and the Human Brain. New York: Penguin Books; 1994. ISBN: 978-0143036227.