I see the opposite in most startups that have a 6 day work week to get ahead of the "slowly moving" 5 day work week competition.

I appreciate Feynman’s contributions—and in fact have been recently revisiting the Messenger lectures—but that seems like an unnecessary jab. The use of “usually” is also a convenient cop-out which makes the remark meaningless because the speaker can pick and choose in any conversation so they always win.¹

I thought about it and picked the first thing which came to mind: Natural science. From Wikipedia²:

> Natural science or empirical science is a branch of science concerned with the description, understanding, and prediction of natural phenomena, based on empirical evidence from observation and experimentation. Mechanisms such as peer review and reproducibility of findings are used to try to ensure the validity of scientific advances.

Seems pretty scientific to me. But alright, let’s check the article to give it a fair shot in context. The only time the word “science” comes up is “Social Sciences”. Again from Wikipedia³:

> Social science (or the social sciences) is one of the branches of science, devoted to the study of societies and the relationships among members within those societies. The term was formerly used to refer to the field of sociology, the original "science of society", established in the 18th century. It now encompasses a wide array of additional academic disciplines, including anthropology, archaeology, economics, geography, history, linguistics, management, communication studies, psychology, sociology, culturology, and political science.

That’s a wide range. Are all of those “not science”?

¹ Assuming your rephrasing is accurate and not missing important context.

² https://en.wikipedia.org/wiki/Natural_science

³ https://en.wikipedia.org/wiki/Social_science

The word 'study' is no sacred possession exclusive to the natural sciences, and there is nothing wrong with properly conducted surveys as a method in sociology, economics or psychology.

If surveys targeting the very people responsible for optimising their businesses' productivity, with no incentive to falsify their conclusions, is good evidence. Without any other way to systematically measure the change in productivity across a plethora of different businesses implementing a four-day workweek, it is as good as it gets — much better than purely theoretical assumptions that productivity must have dropped.

You can find the study here if you wish to critique its methods: https://www.nature.com/articles/s41599-026-07536-x

https://en.wikipedia.org/wiki/Hawthorne_effect

Related to it we have novelty effect and bunch of other psychological effects that are hard to isolate in human science. In this sector, a lot of studies cannot be repeated.

That means the four-day-workweek is even better than we thought it was!