I just tried a very fun and very challenging utilitarian ethics puzzle: The Ultimate Trolley Problem!
Click the link, read the puzzle and see if you can solve it for yourself, preferably BEFORE reading my solution below.
Also, in case you're not familiar with consequentialist/utilitarian ethics and trolley problems I'm just going to spell it out here: the goal here (if you're a consequentialist/utilitarian) is to maximize the expected number of lives saved. Well technically you're trying to maximize total human quality-adjusted life years, so it's really amount of life saved adjusted for quality of life that you're trying to maximize here.
You done? Let's see how your answer compares to mine.
If I were that brain in a vat, I would want to choose for the train to go down the right side of the fork. That way the orphan that would grow up to be Hitler dies AND the war that ends up happening will be the one with no war crimes. Even with a Cartesian demon in my mind intermittently trying to deceive me, without any evidence of how often the cartesian demon tries to deceive me, I'm just going to assume a 50% chance of being deceived on each particular claim. So my choice should be the same as if there was no Cartesian Demon: pick the right side of the fork, right?
Not necessarily. The cartesian demon could also be trying to deceive me about which way is "right" and which is "left". If I assume a 50% chance of apparent left being actual left and 50% chance of it not being actual left, and same for apparent right, then I've got a 50% chance that apparent left is actually right, and a 50% chance that apparent right is actually right. Of course there's also a chance that both apparent directions are actually left or both are actually right, but if that's the case my choice doesn't matter.
So we're faced with a 50% chance of apparent left being actual right, and a 50% chance of apparent right being actual right.
Your best bet in this specific situation is to gather more information about the cartesian demon that is messing with your perception, and if you don't have time for that or if that's simply not feasible, you'll just have to pick a direction at random and hope for the best.
In the alternative form of the problem the solution is basically the same. For the consequentialist half's answer, just pick randomly because of the reasons stated above.
For the absolutist half's answer...the absolutist throws up their hands and can't decide which path for the train to go down. They don't know if they have a preference or even if they should have a preference, although they are leaning towards none and no because you can't weigh up the value of one life against the value of many lives in their opinion. Either they can choose randomly, or they can let the train go down whichever side of the fork it goes down.
Agree? Disagree? Something I missed or didn't account for and should have? Feel free to comment on my solution or post your own solutions below.
Hope you enjoyed that puzzle! I know I sure did.