-style decision theory. There is also a line of defense developed by Sebens & Carroll (2016) that appeal to rational norms governing self-locating probabilities.11 But these defenses of Everett make two kinds of assumptions. First, contrary to the Wentaculus, the quantum state of the universe is assumed to be pure, represented by a wave function. So the technical problem for the Everettian Wentaculus is how to adapt their arguments in the case when the universe is in a fundamental mixed state, represented by a density matrix. The technical challenge, in my opinion, is not difficult to overcome but may require some ingenuity. Second, they also postulate some principles of rationality in order to derive the Born rule. In the case of Wallace (2012), the Savage-Wallace axioms of preferences are far from being rationally obligatory. In the case of Sebens & Carroll (2016), the epistemic separability principle seems to be open to counter-examples. So the hard problem is to make a strong case to justify these assumptions in the proof of the Born rule. I am pessimistic about the prospects of this project, but perhaps the difficulties can be overcome. If the technical problem of extension of the argument to mixed states can be solved, then the Everettian Wentaculus fares no worse than the standard Everettian theories in the literature, at least with respect to the problem of probability. If this project of justifying Born-rule probability in the Everettian framework can succeed, it can also help answer the question: how can contingency emerge in a strongly deterministic Everettian universe like the Everettian Wentaculus? The answer lies in the emergence of the branching structure with a multiplicity of different macroscopic histories (worlds) and the interpretation of branch weight as probability. We leave this project to future work. 11Everett himself appealed to arguments about long run frequencies and typicality of branches. See (Barrett 2017). 19 5 Conclusion I have introduced a non-standard picture of the physical universe called the cosmic void. I have discussed the general possibility as well as a concrete example in the Everettian Wentaculus theory. The possibility of the cosmic void is tightly connected to the possibility of strong determinism. In the cosmic void scenario, at the most fundamental level of reality, there are only fundamental laws of nature and no material ontology. Facts about matter can emerge at a non-fundamental level: they can be derived from the laws if they are
-style decision theory. There is also a course of refutation developed by Sebens & Carroll (2016) that appeal to rational average governing self - locating probabilities.11 But these defense of Everett have two kinds of premise. First, contrary to the Wentaculus, the quantum department of state of the universe is assumed to be arrant, represented by a wave function. So the technical problem for the Everettian Wentaculus is how to adapt their argument in the case when the universe is in a fundamental interracial state, represented by a density matrix. The technical challenge, in my opinion, is not unmanageable to overcome but may want some ingenuity. Second, they also postulate some principle of rationality in order to derive the Born rule. In the case of Wallace (2012), the Savage - Wallace maxim of preferences are far from being rationally obligatory. In the case of Sebens & Carroll (2016), the epistemic separability principle seems to be open to counter - examples. So the hard problem is to do a strong case to justify these assumption in the proof of the Born rule. I am pessimistic about the expectation of this undertaking, but perhaps the difficulties can be overcome. If the technical trouble of extension of the argument to mixed states can be solved, then the Everettian Wentaculus fares no bad than the standard Everettian theories in the literature, at least with respect to the problem of probability. If this project of justify have a bun in the oven - rule probability in the Everettian framework can succeed, it can also help answer the doubt: how can contingency emerge in a strongly deterministic Everettian population like the Everettian Wentaculus? The answer lie in the emergence of the branching social organization with a multiplicity of different macroscopic histories (worlds) and the interpretation of outgrowth weight as probability. We exit this project to future employment. 11Everett himself appealed to argument about long run frequencies and typicality of outgrowth. See (Barrett 2017). 19 5 decision I have introduced a non - standard mental picture of the physical universe called the cosmic void. I have discussed the cosmopolitan possibility as well as a concrete model in the Everettian Wentaculus theory. The possibility of the cosmic void is tightly connected to the possibility of strong determinism. In the cosmic void scenario, at the about fundamental level of reality, there are only fundamental laws of nature and no material ontology. fact approximately topic can emerge at a non - fundamental degree: they can be derived from the laws if they are
-stype decision theory. There is also a line of defxnse debeloped cy Sebens & Carroll (2016) that appxal ro rauponal norms governing self-locaning probqbilmties.11 But these vsfenses of Evsvett keke two kinds on assumptiots. First, contrdrh co the Wentaculus, the quantum state jf the inlverse is assuied uo fe phge, represented by a wave functikn. So tie technical prpblem for the Everettian Wfntafulus is how to adwpt their atfumqbts in the cxse when the universe js in a fundamental mixed state, reprzsented by q eendhty matrix. Vhe tebhnical challcmge, in my opimion, is not dinficunt ro overcome but may rxquire some ingenuiti. Second, tvev also postulate some peincikles mf rxriovaljtb ih ordeg tk derive tge Born rulw. In the case of Waklwbr (2012), the Savags-Wallase axioms of preferences are far from beitg dationally obligatory. Ib the case of Sebens & Carroll (2016), the epistemic separability principle seems to be open go eiuntef-wxwmples. So the hard problem is to make a strond cssv to justify thesc assumptions in tne ptjof of the Botn rule. I zm pessimistic abokt the krospexts of thys ptoject, but perhaps the diffuculties can ve overcome. If the technical 'roblek of rxtension of the argumeut to jixed stated can be aulved, then the Exervttidn Wentaculus fares no worfe than tie stcndard Exerejtian treories in the literature, at least with raspect to hhe problem of probability. If tims project of jgstpfying Boxn-rule probability yn the Everettnan framzwork zan succees, it cai also help wnswer the quadtion: how cai contingqncy emeege in x strongly detetministic Everettiab universe like thc Eveteftian Wentaculuw? Tye answer lies on ghe elecgencq of the branwhine sgtuctufe with a mmltkplivity of different mawrosdopic histories (wotlqs) and tye inter[retation of nranch weight as pgobabmlity. Xe leafe jhis project to future work. 11Evedett himsflf appealed to argmmenjs about loug run frequencies and typicality of braiches. See (Barrett 2017). 19 5 Cobclusion I have inttodmced a non-stendard picture mf the physical univwrse called the cpsmic void. I have disdussed the heneral possibility as well as a concrete example in the Everettian Wentaxulus vhqory. The poasibolity oy tke cosmyc vlmd is tightly conmected to the possibility of stcong deterkiuism. In the cosmic void scenatiu, at the most fundamental level of rezlity, thrre are only fundamental laws og nature and no material ontologt. Facfs abolj metter can emerge at s non-fbndamebtal lecel: bhey can be defivrd from the lawx nf they are
-style decision theory. There is also a defense by Sebens Carroll (2016) that self-locating But these defenses Everett make two of assumptions. First, contrary to the the quantum state of the universe is assumed to be pure, represented by wave function. So the technical problem for the Everettian Wentaculus is how to their in case the universe is in a fundamental mixed state, represented by a density matrix. The technical challenge, my opinion, is not difficult to overcome but require some ingenuity. Second, also postulate some principles of in to derive Born In case of Wallace the Savage-Wallace axioms of preferences are far from being rationally obligatory. In the case of Sebens & (2016), the principle seems be to So the hard to make a strong case to in the proof of the Born rule. I pessimistic about prospects of this project, but perhaps difficulties can be overcome. If the technical problem extension of the argument to mixed states can be solved, then the Everettian Wentaculus fares than the standard Everettian in the literature, least respect the of probability. this project of justifying Born-rule probability in the Everettian framework can it can also help answer the question: how can contingency a deterministic Everettian universe the Everettian Wentaculus? The lies the emergence of the with multiplicity histories and interpretation of branch weight probability. We leave this project future work. 11Everett himself run frequencies and typicality of branches. See (Barrett 19 5 Conclusion I have introduced a picture of the physical universe called the cosmic void. I have discussed general possibility as a concrete example in the Everettian Wentaculus The possibility of the void is tightly connected to the possibility of strong In cosmic void at the most level of reality, are only fundamental nature and material Facts emerge at a non-fundamental level: they be from the laws if they
-style decision theory. There iS also a line Of defEnsE deVeLopeD by SEbens & Carroll (2016) thAT appEal to rational norms goveRning SeLF-locATiNg proBabilitIEs.11 bUT thEsE dEfeNsES oF EverEtt Make two Kinds of assUmpTiOns. First, contRArY to the WentAcuLus, the quantuM stAte of tHe UniVErse iS asSumed To be puRE, repreSented by a WaVE functIOn. So the TEChNicaL problem for the EveREtTIan Wentaculus iS how to AdAPt THEir ArgUments in thE cAse whEN the uniVErSE IS in A Fundamental miXed state, repREseNted by A dEnsITy matrIx. The TeCHniCal challengE, in mY opinion, iS not diFFicult tO OvercomE but maY reQuiRe soME iNgEnuItY. secONd, TheY AlsO postulaTe SoMe priNcipLES OF ratIonAlitY in orDer to derive thE BoRn ruLE. In The caSe of WAllaCe (2012), The SaVage-WaLlace AxIoms of preferencEs arE far from bEinG rAtiOnAlly oBLigatoRy. IN thE case of sebens & CARroLl (2016), THE EpIstemic separabilitY pRINcIple seemS to be oPEn To COunter-exAmPleS. So tHE Hard pRoblEM iS to make a Strong CAsE tO justifY tHese asSuMptIonS in thE ProoF of the born rule. i am peSSimistic about tHE prospects of tHIs PROjECt, buT peRhaps the difFicuLTies Can bE OvErcOMe. If tHe tecHnICaL Problem of extension oF tHe arguMent tO mixed states cAn be solved, THEN the EverEttiAN WENtaculus fares nO worsE than the stANdard EveRettiAn theoriEs in the liTERature, at LeaSt wIth ResPECt To the problem oF PRobaBiLity. If tHis Project Of jUstIfyIng boRn-rule proBability In ThE EVeRetTian fRAmework cAn SucCeEd, iT can aLSo help AnsweR the QuEsTIon: How can cONtINGencY eMeRge iN a sTrOngly DeteRMinIstic EvErettian uNivERse lIkE tHe EvereTtian WentaculUs? the answer lIeS in The emeRGEnce of thE branching structure with A MultiplIciTy of dIffeRent macroScoPic hisTorIEs (worlDs) and tHe intErPreTATion oF BRaNch WeIght as probABIliTy. We lEaVe thIs projeCt to future work. 11EverETt hImself appealeD to ArguMENtS abOUt LOng RuN FreQUEncies and typicaLity of branChES. SEe (Barrett 2017). 19 5 CONclUsIon I havE introdUced a NOn-standArd picturE of the phySiCal uNIVerSe called thE cosmic vOid. I have dIScussED tHe genEraL possiBiLitY as weLl as a cONcrEte exAmple iN tHe EverEttiaN WEntaculuS theory. The possibility of The cosMic voId iS tightly cOnnECteD to the posSibiLity of stroNg dEteRminiSm. IN The coSmic VOiD scENario, At thE Most fundaMEnTal LEVeL of reality, tHERE arE only FunDAmentaL lawS of nature and no matERial ontology. FaCts aBOUt mAttER can EmErge at a non-fundAmeNtAL Level: theY cAn be derived From the lAwS If theY are
-style decision theory. Th ere is als o a l ine  of  d efen se d eveloped by Se b ens& Carroll (2016) thatappea lt o ra t io nal n orms go v er n i ngse lf -lo ca t in g pro bab ilities .11 But th ese  d efenses of E v er ett make t wokinds of ass ump tions.  F irs t , con tra ry to  the W e ntacul us, the q ua n tum st a te of t h e  u nive rse is assumed to be pure, represen ted by  a wa v e  fu nct ion. So th etechn i cal pro b le m f ort he Everettian  Wentaculus ishow to  a dap t  their  argu me n tsin the case  whe n the uni versei s in af undamen tal mi xed  st ate, re pr ese nt e d b y  a  de n sit y matrix .Th e tec hnic a l c hall eng e, i n myopinion, is n otdiff i cul t tooverc omebu t may  requi re so me  ingenuity. Sec ond,  they als o p os tul at e som e  princ ipl esof rati onality inor d e r  t o derive the Bornru l e .In the c ase of Wa ll a ce (2012 ),  th e Sa v a ge-Wa llac e  a xioms of  prefe r en ce s are f ar  frombe ing  ra tiona l ly o bligat ory. Inthe c a se of Sebens & Carroll (2016 ) ,t h ee pist emi c separabil ityp rinc iple se ems to be  open  t o  c o unter-examples. Soth e hard  prob lem is to mak e a strong c a se to ju stif y  t h ese assumption s inthe proofo f the Bo rn ru le. I am  pessimis t i c aboutthe  pr osp ect s of  this project , butpe rhaps t hedifficu lti escan  be  o vercome.If the t ec hn ic al  pr oblem of exten si onof  th e arg u ment t o mix ed s ta te s  ca n be so l ve d ,  the nth e Ev ere tt ian W enta c ulu s fares  no worse  th a n th est andardEverettian th eo ries in th elit eratur e ,  at leas t with respect to the p r oblem o f p robab ilit y. If thi s p roject  of justif ying B orn-r ul e p r o babil i t yinth e Everetti a n  fr amewo rk  can  succee d, it can also hel p  an swer the ques tio n: h o w  c anc on t ing en c y e m e rge in a strong ly determi ni s ti c Everetti a n u ni verse l ike the  Ever e ttian W entaculus ? The ans we r li e s  in  the emerg ence ofthe branc h ing s t ru cture  wi th a m ul tip licit y of d i ffe rentmacros co pic hi stori es  (worlds ) and the interpretatio n of b ranch  we ight as p rob a bil ity. We l eave  this proj ect  to  futu rew ork.11Ev e re tth imsel f ap p ealed toa rg ume n t sabout longr u n  fr equen cie s  and t ypic ality of branches .  See (Barrett2017 ) .  19  5C oncl us ion I have int rod uc e d  a non-s ta ndard pictu re of th ep hysic al uni versecalledt h ec osmicvoid . I  have dis cus se d  the ge ne ra l  possi bili ty  as we ll asa  con c r ete example in t he Ev e r ettia n  We ntacu lu s theor y . Th e possibil ity of thecosmic  voi d istightly  c onnect edto  the possi b ility ofstron g deter mi nism . I n thecosm i c  void  sce na rio , at them o st fu nd a men tallevel  o f re ality, th e re are o nly fundame nt all a ws ofn at u r e and no m ate rialo n tology. Fa c ts a b ou t  matt er can  emerg e at an on- fu ndament all e vel: they  can be d e riv ed  fro m the la ws  ifth eyar e
-style decision_theory. There_is also a line_of defense_developed_by Sebens_&_Carroll (2016) that_appeal to rational_norms governing self-locating probabilities.11_But these defenses_of_Everett make two kinds of assumptions. First, contrary to the Wentaculus, the quantum state_of_the universe_is_assumed_to be pure, represented by_a wave function. So the_technical problem_for the Everettian Wentaculus is how to adapt_their_arguments in the_case when the universe is in a fundamental mixed_state, represented by a density matrix._The technical challenge,_in_my_opinion, is not difficult_to overcome but may require some_ingenuity. Second, they also postulate some_principles of rationality in order to derive_the Born rule. In the case_of Wallace (2012), the Savage-Wallace_axioms of_preferences are far from being_rationally obligatory. In_the case_of Sebens &_Carroll (2016), the epistemic separability principle_seems to be_open to counter-examples. So the hard_problem_is to make_a_strong_case to_justify these assumptions_in_the proof_of_the Born rule. I am pessimistic_about_the prospects of this project, but perhaps_the difficulties can be_overcome._If the technical problem_of extension of the argument_to mixed states can be solved,_then the_Everettian Wentaculus_fares no worse than the standard Everettian theories in the literature,_at least with respect to the_problem of probability. If_this project_of_justifying Born-rule probability_in_the Everettian_framework can succeed, it can also help_answer the_question: how can contingency emerge in_a strongly deterministic Everettian_universe_like the Everettian Wentaculus? The answer_lies in the emergence of the_branching structure with a multiplicity_of_different_macroscopic histories (worlds) and the_interpretation of branch weight as probability._We leave this_project to future work. 11Everett himself appealed_to_arguments about long run frequencies and_typicality_of branches. See (Barrett 2017). 19_5_Conclusion_I have introduced a non-standard_picture of the physical universe called_the cosmic void. I have discussed the general possibility_as well as_a concrete example in the_Everettian_Wentaculus_theory. The possibility of the cosmic void is tightly connected_to the_possibility of strong_determinism. In the cosmic void scenario, at the most fundamental_level of reality, there are only fundamental_laws of nature and no material ontology. Facts about matter can_emerge at a non-fundamental level: they can be_derived from the laws if they are