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machine,  and  so  on,  in  arbit rarily  many  steps  of  iteration.  If  we  do  go  on  to  create 

our  own  ancestor ‐ simulations,  this  would  be  st rong  evidence  against  (1 )  and  (2), 

and  we  would  therefore  have  to  conclu de  that  we  li ve  in  a  simulation.  Moreover, 

we  would  have  to  suspect  that  the

 posthumans  runni ng  our  simulation  are 

themselves  simulated  beings;  and  their  creators,  in  turn,  may  also  be  simula ted 

beings. 

 Reality  may  thus  contain  ma ny  levels.  Even  if  it  is  necessary  for  the 

hierarchy  to  bottom  out  at  some  stage  –  the  metaphysical  sta tus  of  this  claim  is 

somewhat  obscure  –  there

 ma y  be  room  for  a  la rge  number  of  level s  of  reality, 

and  the  numb er  could  be  increasing  over  time.  (One  consideration  that  counts 

again st  the  multi ‐ level  hypothesis  is  tha t  the  computational  cost  for  the 

basement ‐ level  simulators  would  be  very  great .  Simulating  eve n  a  single 

posthuman  civili zation  might  be 

prohibitively  exp ensive .  If  so,  then  we  shou ld 

expect  our  simulation  to  be  terminated  when  we  are  about  to  become 

posthuman .) 

 Although  all  the  elements  of  such  a  system  can  be  naturalistic ,  even 

physical,  it  is  possible  to  draw  som e  loose  analogi es  with  reli gious  conceptions  of 

the  world.  In  some  ways, 

the  posthumans  running  a  simulation  are  like  gods  in 

relation  to  the  people  inha bit ing  the  simulation:  the  posthumans  created  the 

world  we  see;  they  are  of  superior  intelligenc e;  they  are  “omnipotent”  in  the 

sense  that  they  ca n  interfere  in  the  worki ngs  of  our  wor ld  even  in  ways  that 

violate  its  physi cal

 laws;  and  they  are  “omni sc ien t”  in  the  sense  that  they  can 

monitor  everything  that  happens.  However,  al l  the  demigods  except  those  at  the 

fundamental  level  of  re ality  are  su bject  to  sanct ions  by  the  more  powerful  gods 

living  at  lower  levels. 

Further  rumination  on  these  themes  could  climax  in  a  naturalistic 

theog ony 

that  would  study  the  structure  of  this  hierarchy,  and  the  constraints  imposed  on 

its  inha bitants  by  the  possibility  that  their  actions  on  their  own  level  may  affect 

the  treatment  they  recei ve  from  dwellers  of  deeper  levels.  For  example,  if  nobody 

can  be  sure  that  they  are  at  the  basement ‐ level,

 then  everybody  would  have  to 

consider  the  possibility  that  their  actio ns  will  be  rewarded  or  punished,  based 

perha ps  on  moral  criteria ,  by  their  simulators.  An  afterlife  would  be  a  real 

possibi lity.  Be caus e  of  this  fundame ntal  uncertainty,  even  the  basement 

civilization  may  have  a  rea son  to  behave  ethically.  The  fact  that 

it  has  such  a 

reason  for  moral  behavior  would  of  course  add  to  everybody  else’s  reason  for 

behaving  morally,  and  so  on,  in  truly  vi rtuous  ci rcl e.  One  mi ght  get  a  kind  of 

universal  ethical  imperative,  wh ich  it  would  be  in  everybody’s  self ‐ interest  to 

obey,  as  it  were  “from  nowhe re”. 

In

 addi tio n  to  a ncestor ‐ simulations,  one  may  also  consider  the  possibility 