In possible worlds Counterpart theory

1 in possible worlds

1.1 overlapping individuals
1.2 trans-world individuals
1.3 haecceity

in possible worlds

david lewis defended modal realism. view possible world concrete, maximal connected spatio-temporal region. actual world 1 of possible worlds; concrete. because single concrete object demands spatio-temporal connectedness, possible concrete object can exist in 1 possible world. still, true things like: possible hubert humphrey won 1968 presidential election. how true? humphrey has counterpart in possible world wins 1968 election in world.

lewis argues against 3 other alternatives might compatible possibilism: overlapping individuals, trans-world individuals, , haecceity.

some philosophers, such peter van inwagen (1985), see no problem identity within world . lewis seems share attitude. says:

… holy roman empire, badly named. […] in first place should bear in mind trans-world airlines intercontinental, not yet interplanetary carrier. more important, should not suppose have here problem identity.


we never have. identity utterly simple , unproblematic. identical itself; nothing ever identical else except itself. there never problem makes identical itself; nothing can ever fail be. , there never problem makes 2 things identical; 2 things never can identical.


there might problem how define identity sufficiently lacking in conceptual resources — note won t suffice teach him rules of inference — since such unfortunates rare, among philosophers, needn t worry if condition incurable.


we state plenty of genuine problems in terms of identity. needn t state them so.” (lewis 1986:192-193)

overlapping individuals

an overlapping individual has part in actual world , part in world. because identity not problematic, overlapping individuals having overlapping worlds. 2 worlds overlap if share common part. properties of overlapping objects are, lewis, troublesome (lewis 1986:199-210).

the problem object’s accidental intrinsic properties, such shape , weight, supervene on parts. humphrey have property of having 6 fingers on left hand. how that? can’t true humphrey has both property of having 6 fingers , 5 fingers on left hand. might has 5 fingers @ world , 6 fingers @ world. how should these modifiers understood?

according mcdaniel (2004), if lewis right, defender of overlapping individuals has accept genuine contradictions or defend view every object has properties essentially.

how can 1 year older are? 1 way there possible world exist. way have counterpart in possible world, has property of being 1 year older you.

trans-world individuals

take humphrey: if trans-world individual mereological sum of of possible humphreys in different worlds. road goes through different regions. there parts overlap, can there northern part connected southern part , road mereological sum of these parts. same thing humphrey. 1 part of him in 1 world, part in world.

possible exist iff possible whole exist. is, iff there world @ whole of exists. is, iff there world such quantifying on parts of world, whole of exists. is, iff whole of among parts of world. is, iff part of world – , hence not trans-world individual. parts of worlds possible individuals; trans-world individuals therefore impossible individuals.

haecceity

a haecceity or individual essence property single object instantiates. ordinary properties, if 1 accepts existence of universals, can exemplified more 1 object @ time. way explain haecceity distinguish between suchness , thisness, thisness has more demonstrative character.

david lewis gives following definition of haecceitistic difference: “two worlds differ in represent de re concerning individual, not differ qualitatively in way.” (lewis 1986:221.)

ct not require distinct worlds distinct possibilities – “a single world may provide many possibilities, since many possible individuals inhabit it” (lewis 1986:230). ct can satisfy multiple counterparts in 1 possible world.