# Moral contagion heuristic

> "Remember that time you went roller-skating with pink eyebrows? I was embarrassed even though it wasn't me, but because you're my mom." - My 7 year old

A prevalent and arguably universal human cognitive bias is the contagion heuristic - the idea that mere contact or association with a bad thing or person reflects badly on you. At a relatively young age, my daughter had picked up that others might judge her for her association with me. 

> "A [contagion heuristic](https://en.wikipedia.org/wiki/Contagion_heuristic) is [psychological heuristic](https://en.wikipedia.org/wiki/Heuristics_in_judgment_and_decision_making) which follows the [law of contagion](https://en.wikipedia.org/wiki/Law_of_contagion) and the [law of similarity](https://en.wikipedia.org/wiki/Law_of_Similarity)."

But would these others be rational in doing so? 

In fact, the reason my eyebrows were pink were because my daughter had coloured them that way herself, the day before. We are also connected socially; they might consider her culpable for not noticing earlier and preventing me from leaving the house in such a state. (She ushered me to the bathroom on arriving at roller skating, but it was difficult to get it off without make-up remover.) 

But there are clearly times in which the contagion heuristic is wrong. The clearest examples come from inaccurate assessment of the contagiousness of a disease. Historically some people believed diseases like cancer were contagious. Cancer patients were treated badly or shunned accordingly. The same was true for HIV patients, where ignorance about transmission risk caused people to be afraid to shake their hands. (Princess Diana gained moral status for shaking hands with HIV patients; Boris Johnson lost some for doing the same with COVID-19 patients).

With diseases, science helps us get this right. But what about moral contagion? Is morality... contagious? Or at least, does associating with someone with poor morals [signal](https://www.lesswrong.com/posts/vzyhBN2SZpvqER4ao/an-introduction-to-signalling-theory) you might also have poor morals?

> "Moral contagion is a phenomenon in which individuals or objects take on the moral essence of the people who are associated with them." [^ch10zfcz8al]

First, we can say what little evidence we have suggests that morality is at least in part contagious. This makes sense; morality is at least in part socially constructed, and moral messages do spread contagiously[^6ohvhgemnjy] and can have long term impact.[^xvxzcdm3yqh]

But even if morality weren't contagious at all, the [law of similarity](https://en.wikipedia.org/wiki/Law_of_Similarity) still applies here. In the case of Jeffery Epstein, it was less that people associated with him were thought to have become sexual predators because of him, but rather that they too were engaging in such behaviour. Sexual predation itself doesn't have to be contagious, as long as social relationships between similar people are.

The MIT Media Lab had reasoned that contagion heuristic was wrong, and that instead they had a moral responsibility to take Epstein's money.[^4yulvqcj7ly] But the moral contagion did eventually spread to MIT, too, despite the fact they took precautions to hide the relationship.[^4yulvqcj7ly] 

[^ch10zfcz8al]: Liu J, Liao C, Lu J, Luo YJ, Cui F. Moral contagion: Devaluation effect of immorality on hypothetical judgments of economic value. Hum Brain Mapp. 2019 May;40(7):2076-2088. doi: 10.1002/hbm.24508. Epub 2019 Jan 9. PMID: 30624839; PMCID: PMC6865687. 

[^6ohvhgemnjy]: Brady, William J., and Jay J. Van Bavel. “Estimating the Effect Size of Moral Contagion in Online Networks: A Pre-registered Replication and Meta-analysis.” OSF Preprints, 7 Apr. 2021. https://osf.io/s4w2x/ 

[^xvxzcdm3yqh]: MacAskill, William (2022). What We Owe the Future. New York: Basic Books. ISBN 978-1-5416-1862-6. OCLC 1288137842. 

[^4yulvqcj7ly]: https://www.vox.com/future-perfect/2019/9/11/20860717/mit-media-lab-joi-ito-epstein