EA Concepts: Share Impressions Before Credences

by Aaron Gertler18th Sep 20186 comments


Epistemic Humility

Hello, readers! I'm trialing for the Content position at CEA; as such, I've been asked to draft a couple of posts for the concept map. These are meant to be close to the current style (no links in body text, fairly concise).

I'd love to hear your feedback on this post. Specific questions:

1. What are your favorite words for "beliefs before updating on outside information" and "beliefs after updating on outside information"? We're trying to draw that distinction with "impression" and "credence", but those may not be the best options.

2. When you imagine this from the view of a reader who is newish to EA, and clicked on a link to read about the importance of "sharing your impressions", does it make sense? Is it clear why this concept is useful

3. Are there any other links we should add to "further reading"? (In particular, I think that a link to the Soviet example of "everyone hates the government but is afraid to say so" might be relevant, but I couldn't find a good article summarizing the example.)

Thanks for your help! The other concept draft is here.

Share Impressions Before Credences

When we think through a question by ourselves, we form an “impression” of the answer, based on the way we interpret our experiences. (Even if you experience something that others have also experienced, what you take away from that is unique to you.)

When we discuss a question with other people, we may update our “impression” into a “credence” after updating on their views. But this can introduce bias into a discussion. If we update before speaking, then share our updated credences rather than our impressions, our conversation partners partly hear their own views reflected back to them, making them update less than they should.

Consider two friends, Aaron and Max, who are equally good weather forecasters. Aaron has the impression that there is a 60% chance of rain tomorrow. He tells Max about this. Max had formerly had the impression that there was an 80% chance of rain tomorrow, but he updates on Aaron’s words to reach a credence of 70%.

Aaron then asks Max for his view. Max tells him he thinks there’s a 70% chance of rain, so Aaron updates to reach a credence of 65%. Both friends used the same decision algorithm (average both probabilities), but because Aaron shared his impression first, and Max shared a view that “reflected” that impression, Aaron failed to update in the same way as Max.

This dynamic explains why it can be important to share your initial impressions in group discussions, even if they no longer reflect your up-to-date credences. Doing so helps all participants obtain as much information as possible from each participant’s private experience.

Further Reading:

Kawamura, Kohei, and Vasileios Vlaseros. 31 July 2014. “Expert Information and Majority Decisions”.