# How does real world expected utility maximization work?

I would like to ask for help on how to use expected utility maximization, _in practice_, to maximally achieve my goals.

As a real world example I would like to use the post '[Epistle to the New York Less Wrongians](/lw/5c0/epistle_to_the_new_york_less_wrongians/)' by Eliezer Yudkowsky and his visit to New York.

_How did Eliezer Yudkowsky compute that it would maximize his expected utility to visit New York?_

It seems that the first thing he would have to do is to figure out what he really wants, his _preferences_^1^, right? The next step would be to formalize his preferences by describing it as a _utility function_ and assign a certain number of _utils_^2^ to each member of the set, e.g. his own survival. This description would have to be precise enough to figure out what it would mean to maximize his utility function.

Now before he can continue he will first have to compute the _expected utility_ of computing the expected utility of computing the expected utility of computing the expected utility^3^ ... and also compare it with _alternative heuristics_^4^.  

He then has to figure out each and every possible action he might take, and study all of their _logical implications_, to learn about all _possible world states_ he might achieve by those _decisions_, calculate the utility of each world state and the average utility of each action leading up to those various possible world states^5^.

To do so he has to figure out the _probability_ of each world state. This further requires him to come up with a _prior probability_ for each case and study all available _data_. For example, how likely it is to die in a plane crash, how long it would take to be cryonically suspended from where he is in case of a fatality, the crime rate and if aliens might abduct him (he might _discount_ the last example, but then he would first have to figure out _the right level of small probabilities_ that are considered too unlikely to be relevant for judgment and decision making).

I probably miss some technical details and got others wrong. But this shouldn't detract too much from my general request. Could you please explain how Less Wrong style rationality is to be applied practically? I would also be happy if you could point out some worked examples or suggest relevant literature. Thank you.

I also want to note that I am [not the only one](http://blog.muflax.com/2012/02/22/the-end-of-rationality/) who doesn't know how to actually apply what is being discussed on Less Wrong in practice. From the comments:

> You can’t believe in the implied invisible and remain even remotely sane. \[...\] (it) doesn’t just break down in some esoteric scenarios, but is utterly unworkable in the most basic situation. You can’t calculate shit, to put it bluntly.  
>   
> None of these ideas are even remotely usable. The best you can do is to rely on fundamentally different methods and pretend they are really “approximations”. It’s complete handwaving.  
>   
> Using high-level, explicit, reflective cognition is mostly useless, beyond the skill level of a decent programmer, physicist, or heck, someone who reads Cracked.

I can't help but agree.

**P.S.** If you really want to know how I feel about Less Wrong then read the post '[Ontological Therapy](http://blog.muflax.com/2012/03/08/ontological-therapy/)' by user:muflax.

^1\. What are "preferences" and how do you figure out what long-term goals are stable enough under real world influence to allow you to make time-consistent decisions?^

^2\. How is utility grounded and how can it be consistently assigned to reflect your true preferences without having to rely on your intuition, i.e. pull a number out of thin air? Also, will the definition of utility keep changing as we make more observations? And how do you account for that possibility?^

^3\. Where and how do you draw the line?^

^4\. How do you account for model uncertainty?^

^5\. Any finite list of actions maximizes infinitely many different quantities. So, how does utility become well-defined?^