Dealing with UFO claims

"I don't know" -> "the best next step is congressional hearings" is QUITE a leap, and includes a whole lot of underlying probability assignments.  AT LEAST it implies that the probability is high enough to spend effort on, and that somehow congress can dissolve a conspiracy that's lasted decades.

Personally, I still assign a vanishingly low probability to aliens.  But I assign enough probability to more prosaic malfeasance (military or private-group technology and behavior, and conspiracy to mislead both the public and the leadership of multiple countries including the conspirators' own and allies) that I'd be happy to see investigations into it.  I don't know that public hearings are likely to be effective - some mix of private/journalistic investigation and still-secret-but-more-formal government investigation would be my best guess.

Moreover, I assign a very low probability that MY effort spent on the topic matters very much.  I'm pretty much thinking about it for entertainment purposes.  

Here's one plausible alternative explanation of the facts that I happened to come across on Twitter: https://twitter.com/erikphoel/status/1667197430197022722

While I would like to know whether or not aliens visited earth, I think it's more useful to simply take the stance "I don't know" instead of thinking in terms of probability.

You can't really "not think in terms of probability" by refusing to think about them explicitly. It can sometimes be a useful exercise to think about or write down everything in terms of numerical probabilities and likelihoods and then throw that away and "go with your gut", but if your beliefs are coherent they imply an underlying probabilistic model, whether you acknowledge it or not.

The mental moves of directly rounding down to "my priors against aliens are high" -> "no aliens" -> "no need to do anything" is bad as if enough people hold it we won't get more evidence. 

Investigating the question of whether aliens have visited earth may be valuable enough to overcome the low prior. However, I predict in advance that congressional hearings are not going to yield much evidence on this question one way or the other, unless they're focused on investigating e.g. the specific claims in the tweet thread above. In general, these kinds of hearings are not known for their truth-seeking or fact-finding ability.

The mental moves of directly rounding down to "my priors against aliens are high" -> "no aliens" -> "no need to do anything" is bad as if enough people hold it we won't get more evidence. 

Extraordinary clams require extraordinary evidence. Words are not extraordinary evidence, they are just words. Sworn testimonies, documents, blurry images... They are not extraordinary evidence. 

Until and unless something like this surfaces:

"here is a sketch of the propulsion system they used, and this is all totally new and revolutionary" or 

"here is a radiation shielding material that is leaps and bounds ahead of our material science" or 

"here is a sample of their tissues, it converts energy into matter in ways we never conceived of"

I will keep calling BS on just words.

"my priors against aliens are high" -> "no aliens" -> "no need to do anything"

More carefully, value of information is about how credences change in response to outcomes of feasible things that can be done, not about what the credences are a priori.

I haven't seen any civilians, including on LW, actually weigh the cost of assymetric disclosure of US military R&D, which this would probably require? So I think you're really going to have to systematize this framework a bit more before you can justify the lets see them aliens stance.

I'd instead call for a simultaneous disclosure of superpower military R&D from all sides, primarily to halt the omnicidal arms-racing dynamics we're all currently living under, and I really mean that, but by the way, this policy would also justify seeing the aliens.

"my priors against aliens are high" -> "no aliens" -> "no need to do anything" is bad

The priors against aliens should be indeed high, but there could be many other hypothesis which generates observation of objects which looks like alien crafts, and some of them are

• interstellar animals similar to chameleons which poorly mimic anything they see
• lobotomized nanotech-based berserkers trying to stop AI development
• interdimensional tourists and hobbists 
• glitches in GPT-9 where we happened to live as half-activated patterns
• effects of distorted observation in consciousness-causes-collapse interpretation quantum mechanics
• psyop war between US, Russia and China, similar to number stations. 

The mental moves of directly rounding down to "my priors against aliens are high" -> "no aliens" -> "no need to do anything" is bad as if enough people hold it we won't get more evidence.

Well, but my priors against aliens are high. The belief that inevitably still takes precedence due to very high priors until some actual hard evidence comes up is "someone is making up bullshit, either on purpose or because they're delusional or stupid". Plenty of "insiders" sometimes spout complete nonsense in order to get some time in the limelight. The moment I see an actual craft flying by some actual unknown mechanisms, then I start considering more serious options (and aliens aren't the first one anyway).