An Open Letter to Our Students: Doing Interdisciplinary Moral Psychology

This chapter offers some recommendations and guiding principles for conducting interdisciplinary moral psychology research, which will benefit students and experienced scholars alike. It is especially helpful to scholars in the humanities looking to apply scientific methods to their work. Drawing from work at the intersection of philosophy and the cognitive and neural sciences, this chapter offers valuable advice for how to critically evaluate the scientific literature and avoid common pitfalls.

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Moral Cognition: Introduction

Moral Philosophy and the ‘Ethical Turn’ in Anthropology

Moving beyond dichotomies: Liao, S. Matthew (ed.), Moral Brains: The Neuroscience of Morality, Oxford University Press, 2016

Notes

What is the relation between p-values and power? If there is no effect to be detected (i.e., if the null hypothesis is true), then the p-value is uniformly distributed between 0 and 1 (i.e., one is equally likely to get a p-value between 0 and 0.2, between 0.2 and 0.4, etc.), independently of the power of the experiment. If the null hypothesis is false, the larger the power, the more likely it is that one will observe a small p-value (holding constant the effect size used to compute the power of the experiment).

More precisely, it is the probability of obtaining a statistic (a function of the data such as t or F) or a larger one if the null hypothesis is true.

In a recent article, Benjamin et al. (2017) have argued that the 0.05 significance level is insufficiently strict, and have recommended to decrease it to 0.005. They argue that findings at the 0.05 level provide too little evidence and that this lax significance level contributes to the current replication crisis in psychology and other sciences. One of us (EM) is a coauthor of this article and would like the 0.005 significance level to be widely accepted. For discussion, see however Amrhein and Greenland (2017); Lakens et al. (2017); McShane et al. (2017).

Since we’re trying to be encouraging and cheerful, we’ve relegated this advice (15) to a footnote: when you collaborate, be very explicit about work responsibilities and authorial order, from the outset. We’ve seen, and been party to, more than one unfortunate misunderstanding about contributions and credit, and they’re no fun at all. While the occasional tiff is likely unavoidable, hammering out expected contributions and credit before serious work begins is a very useful preventative. Potential discomfort isn’t a reason not to collaborate, but it is a reason to be very clear.

A draft of this paper was presented to the Autumn 2015 meeting of the Moral Psychology Research Group. Many thanks to participants for comments, especially Fiery Cushman, Valerie Tiberius, Maria Merritt, Eddy Nahmias, and Shaun Nichols. We also would like to thank Wesley Buckwalter, David Danks, Benjamin Voyer, and Wayne Wu for comments and suggestions.

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Authors and Affiliations

1. Center for Philosophy of Science, University of Pittsburgh, 817 CL, Pittsburgh, PA, 15260, USA Edouard Machery
2. Philosophy-Neuroscience-Psychology Program & Philosophy Department, Washington University in St. Louis, St. Louis, MO, USA John M. Doris

1. Edouard Machery