Timeline Utilitarianism

To­tal vs av­er­age utilitarianism

Say you have one util­ity (think of util­ity as hap­piness points) and you have to choose be­tween ei­ther cre­at­ing an­other per­son that has two util­ity, or in­creas­ing your own util­ity to two.

Cir­cles are peo­ple. Num­bers are the amount of util­ity. Ar­rows are op­tion­s

A to­tal util­i­tar­ian would choose the first op­tion. It’s the one that gen­er­ates the high­est amount of to­tal util­ity in the next tick (the next mo­ment in time). An av­er­age util­i­tar­ian would choose the sec­ond op­tion since it gen­er­ates the high­est amount of av­er­age util­ity in the next tick.
Here these two the­o­ries ar­gue for how we should ag­gre­gate util­ity for the next mo­ment in time. But how should we ag­gre­gate util­ity over a pe­riod of time?

In­tro­duc­ing timeline utilitarianism

Say you are about to die and you have two util­ity. You have to choose be­tween ei­ther just dy­ing, or dy­ing while cre­at­ing an­other per­son that has one util­ity.

Grey cross is non-existence

Let’s look at how a timeline can ag­gre­gate the to­tal amount of util­ity.
Timeline A has two ticks. You could ag­gre­gate the to­tal amount of util­ity of this timeline by sim­ply adding the two ticks to­gether (2+1). Let’s call this method of ag­gre­gat­ing “to­tal timeline util­i­tar­i­anism”. Here we can see that timeline A would be a bet­ter choice than timeline B since timeline B only has one tick and there­fore only two util­ity.

You could also ag­gre­gate the util­ity of timeline A by tak­ing the av­er­age of the two ticks ((2+1)÷2). Let’s call this method of ag­gre­gat­ing “av­er­age timeline util­i­tar­i­anism”. Here we can see that timeline B would be a bet­ter choice than timeline A since timeline B only has one tick and there­fore two util­ity.

Com­bin­ing mo­ment and timeline utilitarianism

So we have “mo­ment util­i­tar­i­anism” to look at mo­ments in time and “timeline util­i­tar­i­anism” to look at the en­tire timeline. What hap­pens if we com­bine them? Let’s in­tro­duce some terms. In “to­tal av­er­age util­i­tar­i­anism” the “to­tal” refers to how we should ag­gre­gate the en­tire timeline. The “av­er­age” refers to how we should ag­gre­gate the in­di­vi­d­ual mo­ments. I will always men­tion the timeline ag­gre­ga­tion first and the mo­ment ag­gre­ga­tion sec­ond. There are four differ­ent com­bi­na­tions that all make differ­ent claims about how we should act.

If we want to max­i­mize to­tal to­tal util­ity we should choose timeline A. If we want max­i­mize av­er­age to­tal util­ity we should choose timeline B. If we want to max­i­mize to­tal av­er­age util­ity we should choose timeline C. If we want to max­i­mize av­er­age av­er­age util­ity we should choose timeline D.
Usu­ally when peo­ple talk about differ­ent types of util­i­tar­i­anism they au­to­mat­i­cally pre­sup­pose “to­tal timeline util­i­tar­i­anism”. In fact, the cur­rent de­bate be­tween to­tal and av­er­age util­i­tar­i­anism is ac­tu­ally a de­bate be­tween “to­tal to­tal util­i­tar­i­anism” and “to­tal av­er­age util­i­tar­i­anism”. I hope this post has pointed out that this as­sump­tion isn’t the only op­tion.

Wrap­ping up

In re­al­ity we have many more op­tions to choose from and we will have to do com­pli­cated prob­a­bil­ity calcu­la­tions un­der un­cer­tainty in­stead of fol­low­ing a sim­ple de­ci­sion tree. Some might ar­gue that non-ex­is­tence should count as zero util­ity. Some might ar­gue for more ex­otic forms of util­i­tar­i­anism like me­dian or mode util­i­tar­i­anism (I hope you don’t spend too much time fret­ting over which of these op­tions is the “cor­rect” form of util­i­tar­i­anism and adopt some­thing like meta-prefer­ence util­i­tar­i­anism in­stead). This is just a sim­plified model to in­tro­duce the con­cept of timeline util­i­tar­i­anism. In fu­ture posts I will ex­pand on this con­cept and ex­plore how it in­ter­acts with things like hingey­ness and choice un­der un­cer­tainty.