What makes us think _any_ of our terminal values aren’t based on a misunderstanding of reality?

Let’s say Bob’s ter­mi­nal value is to travel back in time and ride a dinosaur.

It is in­stru­men­tally ra­tio­nal for Bob to study physics so he can learn how to build a time ma­chine. As he learns more physics, Bob re­al­izes that his ter­mi­nal value is not only ut­terly im­pos­si­ble but mean­ingless. By defi­ni­tion, some­one in Bob’s past rid­ing a dinosaur is not a fu­ture evolu­tion of the pre­sent Bob.

There are a num­ber of ways to cre­ate the sub­jec­tive ex­pe­rience of hav­ing gone into the past and rid­den a dinosaur. But to Bob, it’s not the same be­cause he wanted both the sub­jec­tive ex­pe­rience and the knowl­edge that it cor­re­sponded to ob­jec­tive fact. Without the lat­ter, he might as well have just watched a movie or played a video game.

So if we took the origi­nal, in­no­cent-of-physics Bob and some­how calcu­lated his co­her­ent ex­trap­o­lated vo­li­tion, we would end up with a Bob who has given up on time travel. The origi­nal Bob would not want to be this Bob.

But, how do we know that _any­thing_ we value won’t similarly dis­solve un­der suffi­ciently thor­ough de­con­struc­tion? Let’s sup­pose for a minute that all “hu­man val­ues” are dan­gling units; that ev­ery­thing we want is as pos­si­ble and makes as much sense as want­ing to hear the sound of blue or taste the fla­vor of a prime num­ber. What is the ra­tio­nal course of ac­tion in such a situ­a­tion?

PS: If your re­sponse re­sem­bles “keep at­tempt­ing to XXX any­way”, please ex­plain what priv­ileges XXX over any num­ber of other al­ter­na­tives other than your cur­rent prefer­ence. Are you us­ing some kind of pre-com­mit­ment strat­egy to a sub­set of your cur­rent goals? Do you now wish you had used the same strat­egy to pre­com­mit to goals you had when you were a tod­dler?