Hi Arden and the 80,000 Hours team,

Thank you for the excellent content that you produce for the EA community, especially the podcasts.

There is one issue that I want to raise. I gave serious thought to raising this via your survey, but I think it is better raised publicly.

In your article "The case for reducing extinction risk" (which is linked to in your "Key ideas" article), you write:

Here are some very rough and simplified figures to show how this could be possible. It seems plausible to us that $100 billion spent on reducing extinction risk could reduce it by over 1% over the next century. A one percentage point reduction in the risk would be expected to save about 100 million lives among the present generation (1% of about 10 billion people alive today). This would mean the investment would save lives for only $1000 per person.

At the top of the page, it says the article was published in October 2017 and last updated in October 2017. There are no footnotes indicating any changes were made to that section.

However, an archived copy of the article from June 2018 shows that, at the time, the article read:

We roughly estimate that if $10 billion were spent intelligently on reducing these risks, it could reduce the chance of extinction by 1 percentage point over the century. In other words, if the risk is 4% now, it could be reduced to 3%.

A one percentage point reduction in the risk would be expected to save about 100 million lives (1% of 10 billion). This would mean it saves lives for only $100 each.

I think it would be helpful to members of the community to indicate when and how an article has been substantively updated. There are many ways this can be done, including:

• an article explaining how and why your views have changed (e.g. here, here/here, and here);
• linking to an archived version of the article (as you do here) ideally with a change log; and
• a footnote in the section indicating what it previously said and why your views have changed.

I understand that you have a large amount of content and limited staff capacity to review all of your old content. But what I'm talking about here is limited to changes you choose to make.

I'm sure it was just an oversight on the part of whoever made the change. You all have a lot on your plate, and it's most convenient for an article to just present your current views on the subject.

But when it comes to something as important as the effectiveness of spending to reduce existential risk and something as major as a shift of an order of magnitude, I really think it'd be helpful to note and explain any change in your thinking.

Thank you for reading, and keep up the good work.

Done! Thank you to you and the 80,000 Hours team for building an extraordinary organization.