Let's apply some data to this!

I've been in two high-stakes bad-vibe situations. (In one of them, someone else initially got the bad vibes, but I know enough details to comment on it.) In both cases, asking around would have revealed the issue. However, in both cases the people who knew the problematic person well, had either a good impression of them, or a very bad impression of them. Because there's a pattern where someone who's problematic in some way is also charismatic, or good at making up for it in other ways, etc. So my very rough model of these situations is that there were a bunch of people you could have asked about them and gotten "looks fine" with 60% probability or "stay the fuck away" with 40% probability. If you have only have a few data points of this variety, you'd want to trust your vibes because false negatives can be very costly.

stick to public spaces for a first date, do a web search for the person’s name, establish boundaries and stick to them, be prepared with concrete plans to react to signs of danger, etc.

These mitigations would do nothing against a lot of real relationship failures. Imagine that everything goes swimmingly for the first year. Then you start to realize that even though everything your partner has been doing makes sense on the surface, if you step back and look at the big picture their actions tend to have the effect of separating you from your friends and blaming yourself for a lot of things, and it just doesn't seem healthy. When you finally decide to break up, it's an extremely painful process because: (i) your partner is better at weaving stories than you, and from their perspective you're the problematic person (ii) your friends all know your partner, and they've made a good impression, (iii) you will continue to see them at social events, and (iv) even after all of this, you don't think they ever purposefully acted maliciously toward you.

Or in the words of Sean Carroll's Poetic Naturalism:

1. There are many ways of talking about the world.
2. All good ways of talking must be consistent with one another and with the world.
3. Our purposes in the moment determine the best way of talking.

A "way of talking" is a map, and "the world" is the territory.

The orthogonality thesis doesn't say anything about intelligences that have no goals. It says that an intelligence can have any specific goal. So I'm not sure you've actually argued against the orthogonality thesis.

And English has it backwards. You can see the past, but not the future. The thing which just happened is most clear. The future comes at us from behind.

Here's the reasoning I intuitively want to apply:

$(X\to Y)\to P\left[Y|Z\right]\ge P\left[X|Z\right]$

where X = "you roll two 6s in a row by roll N", Y = "you roll at least two 6s by roll N", and Z = "the first N rolls are all even".

This is valid, right? And not particularly relevant to the stated problem, due to the "by roll N" qualifiers mucking up the statements in complicated ways?

Where's the pain?

Sure. For simplicity, say you play two rounds of Russian Roulette, each with a 60% chance of death, and you stop playing if you die. What's the expected value of YouAreDead at the end?

• With probability 0.6, you die on the first round
• With probability 0.4*0.6 = 0.24, you die on the second round
• With probability 0.4*0.4=0.16, you live through both rounds

So the expected value of the boolean YouAreDead random variable is 0.84.

Now say you're monogamous and go on two dates, each with a 60% chance to go well, and if they both go well then you pick one person and say "sorry" to the other. Then:

• With probability 0.4*0.4=0.16, both dates go badly and you have no partner.
• With probability 20.40.6=0.48, one date goes well and you have one partner.
• With probability 0.6*0.6=0.36, both dates go well and you select one partner.

So the expected value of the HowManyPartnersDoYouHave random variable is 0.84, and the expected value of the HowManyDatesWentWell random variable is 0.48+2*0.36 = 1.2.

Now say you're polyamorous and go on two dates with the same chance of success. Then:

• With probability 0.4*0.4=0.16, both dates go badly and you have no partners.
• With probability 20.40.6=0.48, one date goes well and you have one partner.
• With probability 0.6*0.6=0.36, both dates go well and you have two partners.

So the expected value of both the HowManyPartnersDoYouHave random variable and the HowManyDatesWentWell random variable is 1.2.

Note that I've only ever made statements about expected value, never about utility.

Probability of at least two success: ~26%

My point is that in some situations, "two successes" doesn't make sense. I picked the dating example because it's cute, but for something more clear cut imagine you're playing Russian Roulette with 10 rounds each with a 10% chance of death. There's no such thing as "two successes"; you stop playing once you're dead. The "are you dead yet" random variable is a boolean, not an integer.

If you're monagamous and go to multiple speed dating events and find two potential partners, you end up with one partner. If you're polyamorous and do the same, you end up with two partners.

One way to think of it is whether you will stop trying after the first success. Though that isn't always the distinguishing feature. For example, you might start 10 job interviews at the same time, even though you'll take at most one job.

However it is true that doing something with a 10% success rate 10 times will net you an average of 1 success.

For the easier to work out case of doing something with a 50% success rate 2 times:

• 25% chance of 0 successes
• 50% chance of 1 success
• 25% chance of 2 successes

Gives an average of 1 success.

Of course this only matters for the sort of thing where 2 successes is better than 1 success:

• 10% chance of finding a monogamous partner 10 times yields 0.63 monogamous partners in expectation.
• 10% chance of finding a polyamorous partner 10 times yields 1.00 polyamorous partners in expectation.

EDIT: To clarify, a 10% chance of finding a monogamous partner 10 times yields 1.00 successful dates and 0.63 monogamous partners that you end up with, in expectation.