PHIL315 Lecture Notes - Lecture 22: Modal Realism, Existential Quantification
2 May 2018
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4/30
Lewis on time vs. modality
❖ Time eteralis
o All times exist (past, present, future)
o All times are ontologically equivalent
o Preset, o et. are indexical same view on time as space; there is the
preset tie, o, ut there are all the other possile ties as ell… there
are other times (existential quantification over those times) all depends on when
we happen to be speaking
o All times exist and are the same as the present time.. they are just not now,
now!
❖ Modality – modal realism
o All possible worlds exist – the actual world, is just one of the infinitely many
different worlds
o All possible worlds are ontologically equivalent – they all exist in the same way
o Atual is indexical – picks out the world that you are in
❖ there are differences between fictional characters and fresh and blood
Objections
❖ Everything is actual – if you think there is just the actual world (concrete totality), then
there is’t athig that is’t a part of the atual orld odal realis sas there is…
ou a’t state odal realis!!!!
a. The other worlds, actually exist, have nothing to do with possibility! Actuality
might have been different, which is what modality is about
b. Even if there are other actual worlds, what does this have to do with modality?
❖ Ad hawk – part of a hypothesis added only to validate your current hypothesis
5/2
How can we know
❖ Nuers are i Plato’s heae… ut ho do e lear atheatis?
❖ Causal theory of knowledge – all knowledge is causal
❖ A problem for math is a problem for Lewis. Modal talk, when truth, is talked about in
addition to the actual world all the other possible worlds that exist. These worlds are
isolated spatially and temporally. But odal koledge do’t just eliee ut ko
that is in part, knowledge going on in other worlds
❖ But how can we know about these other worlds if we are causally isolated from the
other worlds?
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