I did a web search on the above phrase, in prep for a podcast, and in ten pages of results didn’t find anything I thought reasonable. Which promotes me to write this, hoping it can show up for others when they so search. This content isn’t new, just restated, maybe better.
When considering purported evidence for meteors or ball lightning, we are much more forgiving than when considering purported evidence of telepathy or ghosts, as reasonable priors for the former are much higher than for the latter. That is, we more easily believe that former cases happened. The assumptions we’d have to make to let us think that we’d seen examples of the latter seem far more extreme.
When considering purported evidence for aliens-on-Earth, we should similarly ask how extreme are the assumptions we’d need to make to make sense of it. Many have dismissed and ridiculed such sightings, even when many independent sober folks all say they saw roughly the same amazing things, largely on the basis of claiming that aliens-on-Earth requires extreme assumptions, and so has a very low prior. I disagree.
To evaluate a prior re aliens-on-Earth, we should collect the key facts in need of explanation, seek the most plausible assumptions required to predict those, estimate an a priori chance for each assumption, and combine those into a total prior chance. Here are the key facts, as I see them, for a minimal aliens-on-Earth concept.
The universe looks dead, untouched by life or civilization, both far and near.
We are still alive on Earth, and have not been killed off by aliens.
Any aliens on/near Earth haven’t changed, built, or done much noticeable.
While advanced aliens could be either totally invisible or very obvious, most seen on Earth are instead near the edge of visibility.
Most aliens seen are impressive, but not doing much useful, or helpful, or hostile.
I’d respect others who tried similarly to list the key data to be explained, and then offered their highest prior explanation of this data, even if they disagreed with mine.
Here are my best guess highest-prior assumptions (with priors) to predict these minimal aliens-on-Earth concept facts, in addition to our usual consensus cosmology:
(0.3-1) Grabby aliens model, which estimates that such aliens appear ~ once per million galaxies, at median date of now, then expand at near light speed.
(0.01-0.1) Life started at Eden, then panspermia seeded Sun’s ~10K # stellar nursery, then a ~Klyr distant Sun sibling made advanced aliens many Myr ago.
(0.01-0.1) Aliens made no-colonize rule. As siblings might break it, sent team to Earth w/ goal: persuade us to follow rule; kill us as last resort.
(0.3-1) Team given low discretion, simple plan: domesticate Earth via be near, impressive, not too hostile, don’t show more that might give us the ick.
The total prior here is 10-5 to 10-2, mid estimate of ~3x10-4. This is higher than the typical ~10-6 prior in a murder trial, so it is high enough to take seriously.
Here are some added facts that would also need to be explained under less minimal concepts of aliens-on-Earth:
Aliens often grab humans, do stuff to them, that they notice and remember.
Alien ships often break and crash.
Alien ships often contain bio-squishy residents.
To explain these added facts, I’d add more assumptions, like:
(0.03-0.3) Alien team at Earth has somewhat escaped home control.
(0.03-0.3) Alien tech/ability has rotted, they are now often incompetent.
(0.03-0.3) Alien made rule requiring bio-squishy forms, at least at Earth.
So I’m more skeptical of reports with these features.
Convido a ler meus argumentos sobre aliens. Gostei do artigo!