Fair recognition of mistakes is essential to improving our political judgment. On this page I go over a variety of errors in political judgment - some made by me in the past, and some made by other people whose views have been close enough to my own that they can still provide cautionary tales for myself and for the interested reader.
I'm not going to list all the times where I or likeminded people made a judgment which was subsequently vindicated by history. This would be a much larger project than enumerating the mistakes, and it would be a lot more boring to write and to read, so I am delaying that project until some other day. For now, note that some mistakes in judgment are inevitable, and if a thought process produces the right answer nine times out of ten, it may be best to stick with it rather than switching to an alternative that may be even worse. So use this page as a resource to be more mindful about ways that I or you can make mistakes, but don't use it to draw sweeping conclusions about methodologies and ideologies.
In the mid 20th century, overpopulation was a very common worry among intellectuals. The government of China implemented severe family restrictions on this basis, cutting their future population by a huge amount, perhaps hundreds of millions. Now we know that this was a catastrophic misjudgment. I feel that had I lived at the time, I likely would have been persuaded by expert warnings about overpopulation and might have supported harmful family planning policies. However I don't know much about the history of this debate. A more serious analysis of what people were arguing at the time would help illuminate whether the overpopulation 'bomb' was indeed an expert consensus and whether it had the kinds of arguments that would have persuaded me, or if it had flaws that could have been spotted ahead of time.
Sometimes I just haven't done enough research to fully understand an issue, and putting in more time and effort reveals flaws in my previous views. The short story with these errors is that I know how to avoid them, I just don't always get around to actually doing the necessary work.
When debate grew in early 2021 about whether we should withdraw from Afghanistan, I was initially slightly opposed to withdrawal, and assumed based on some headlines that the Taliban had violated the deal that the Trump administration had signed with the Taliban. I did not think much about the deal because hardly anyone in the Western foreign policy community was really talking about it - all debate over Afghanistan focused on the merits and ignored the obligations of the deal. But upon looking more closely, I realized that the Taliban had in fact complied with the deal for all practical intents and purposes and so the US ought to withdraw as a matter of principle.
I gave Trump an excessively low score for great power politics in my 2020 presidential evaluation. He was still a bad president in this respect, but not as bad as I judged. The cause of this error was that I wrote the report by accumulating a long list of particular incidents (especially the most newsworthy ones, which reflected very poorly on the administration) but never adequately stepped back towards a holistic consideration of progress and setbacks.
Sometimes I just don't make the right calls due to failures in judgment or unsolved research questions.
In 2020 I produced a model estimating the benefits and harms of Black Lives Matter protests. Initially, I (and apparently every epidemiologist and political commentator who addressed the matter directly) assumed that the protests would aid the spread of COVID-19, and I counted that as by far the greatest harm of the protests. However, research subsequently suggested that the protests actually had no impact or even a negative impact on COVID-19 as, while the protesters became more active, they discouraged lots of other people from going out.
I thought vaccine lotteries were a good idea for encouraging use of the COVID-19 vaccine, but later research showed that they don't work.
Sometimes a 'bad' policy turns out well because of extenuating circumstances, or vice versa. We can't draw clear lessons from these cases, but it is good to keep them in mind. They help us understand the limits of how robust our political judgments can be.
I think Brexit was one example of this. I opposed Brexit at the time based on my general support for internationalism, trade and immigration. I didn't research the issue much at all, but likeminded and better-informed people generally reached the same conclusion. Unfortunately, the COVID-19 pandemic arrived very shortly after Brexit, and many British lives were saved by the fact that they did their own vaccine procurement instead of relying on the terrible EU bureacracy. I've seen people allege that the UK could have done its own vaccine procurement even if it had remained in the EU, but it seems unlikely that they would have actually chosen to do that. I still doubt that Brexit was a good idea considering that such pandemics are generally very rare, but at least in hindsight it seems to have been a good thing.