by absurdmind » Mon Jul 21, 2014 2:02 pm
last night was a 2 hour meeting, and i drank more than i probably should have, so forgive me for forgetting details, misrepresenting views, etc. we decided to go through kind of page by page, summarizing the current arguments, looking at important details, and then raising any concerns. ill try to do something similar with these notes (unfortunately i didnt write notes during the discussion, these are just from memory).
in section 1.1 lewis puts forth an argument in why we should believe in a plurality of worlds. his idea is that his thesis is serviceable/fruitful, and this is some motivation to believe it is correct. basically, he believes that this idea can make better sense of the difficulties that come from talking about possibility. it has less problems than other views, and more going for it.
initially this seems a weird case to make. why should we care that this is a "serviceable" theory? well we can look at this a few ways. its not just about being serviceable, its about making the most sense out of any other theory of possibility. this is in a similar vein to the way theoretical physics works. things like string theory which have no empirical grounding are still supported due to the fact that the idea just makes the most sense.
what if there are various theories that seem to make equal sense? well, this probably wont happen, but if it is the case we should look at this in the most parsimonious manner. this brings us back to something i skipped over that happens on page 2/3. lewis wants to be clear that he believes these worlds exist simpliciter. in other words, they exist, period. he says this and adds that hes not sure what it means for something to exist in a different manner. lewis makes this small claim for a few reasons. it shows that he doesnt want to speak of these as some abstract ersatz entities, this makes sense because lewis is a materialist. all worlds are just as "concrete" as ours. this ties in with a parsimonious view because lewis believes he is paying for "ideology with the coin of ontology". if youre not familiar with quinean terminology: ideology refers basically to "kinds of things", ontology deals with the things that exist. ex: if we believe in donkeys, god, t-shirts, whatever, these are things in our ontology, if we believe in material objects, and non-material objects, we have 2 things in our ontology.
how does this tie in? if we talk about possibility as its own irreducible kind of thing (a primitive), it seems that this gives us a larger ideology, albeit a small ontology. lewis believes its simply an obvious truth that its better to apply occams razor to ideology than ontology. in believing in many concrete worlds, lewis has an ontology of just material objects, although there are lots of them. soon lewis will discuss how belief in primitive modality gives us many more problems with ideology, and problems in general.