- Our not wanting to die is a bit of irrational behavior selected for by evolution. The universe doesn’t care if you’re there or not. The contrasting idea that you are the universe is mystical, not rational.
- The idea that you are alive “now” but will be dead “later” is irrational. Time is just a persistent illusion according to relativistic physics. You are alive and dead, period.
- A cyber-replica is not you. If one were made and stood next to you, you would still not consent to be shot.
- Ditto a meat replica
- If you believe the many worlds model of quantum physics is true (Eliezer does), then there already are a vitually infinite number of replicas of you already, so why bother making another one?
Terminal values and preferences are not rational or irrational. They simply are your preferences. I want a pizza. If I get a pizza, that won't make me consent to get shot. I still want a pizza. There are a virtually infinite number of me that DO have a pizza. I still want a pizza. The pizza from a certain point of view won't exist, and neither will I, by the time I get to eat some of it. I still want a pizza, damn it.
Of course, if you think all of that is irrational, then by all means don't order the pizza. More for me."
Format of the conversation matters. What I saw was a friendly matching of wits, in which of course your father wants to win. If you seriously want to change his mind you may need to have a heart-to-heart -- more like "Dad, I'm worried about you. I want you to understand why I don't want to die, and I don't want you to die." That's a harder conversation to have, and it's a risk, so I'm not out-and-out recommending it; but I don't think it'll sink in that this is serious until he realizes that this is about protecting life.
The counter-arguments here are good, but they stay pretty much in the world of philosophy hypotheticals. In addition to laying it all out cleanly, you may want to say some things that change the framing: compare cryonics to vaccination, say, a lifesaving procedure that was very slow to catch on because it was once actually risky and people took frequent illnesses for granted. Or, cryonics is a bet on the future; it's sad that you would bet against it. If he hasn't seen "You only live twice" show him that. It's not misleading; it actually aids understanding.
The pizza thing you wrote is accurate but it's not how I would put it; it's a step in the direction of abstraction which makes it harder to actually change your mind. I'd use, as a simile, something like people dying of smallpox. I don't want people to die of smallpox, even though the universe doesn't give a damn whether humans live or die, even though there's some parallel universe where smallpox doesn't exist. We're here and we give a damn. We want less death, less destruction of human minds and identities.
It took me at least two decades to realize that there are in deed these different modes of communication. At first glance it sounds so very stupid that this even happens.