David Lewis’s On the Plurality of Worlds: A Modal Realism

A huge thing that philosophy is occupied by is sense data. Sense data (by Royce, Moore and Russell at first) has its characteristics and are data that come from our perceptive senses. The real question is, concerning sense data: Are the sense data representatives of material objects in reality,  or are sense data just images our minds produce with no relation to reality, therefore sense data having no connection to material reality? When I look at a blue cup,  is there really a blue cup there made of plastic particles fusing together to make a good device to carry a drink of choice, or is the blue cup just something that my mind is telling me is there? Many philosophies advocate one or the other, in different variations, such as solipsists believing that if a blue cup is seen, its existence is not known, extremes are taken, when at the same time, philosophies are less extreme. Considering Descartes, an evil deceiver distorts our visual world deceiving us of certain existences, which is another theory on the matter. Realism theories advocate that what we see pertains to real material existences. David Lewis proposing a thesis for the plurality of worlds advocated a modal realism.

Lewis, a philosopher I have only recently encountered the writing of, begins On the Plurality of Worlds by stating his thesis of plurality. He introduces a modal realism stating that all things perceived and sensed are existent and real in some way. The world I see right now with a computer, a blue cup, an iPod touch, my phone, a bunch of books, the blue sky, and everything else is one specific world. If one were to perceive a world where all life has been demolished except that person, that is yet another world. Some people humorously talk about parallel universes, like if I have blonde hair, blue eyes and am white, my parallel universe world would involve me with black hair, brown eyes, and black, and where everything else is opposite the way things are in the first world.

If one can perceive it, it is a possible world. Lewis puts it very well: “The worlds are many and varied. There are enough of them to afford worlds where (roughly speaking) I finish on schedule [his book], or I write on behalf of impossibilia, or I do not exist, or there are no people at all, or the physical constants do not permit life, or totally different laws govern the doings of alien particles with alien properties. There are so many other worlds, in fact, that absolutely every way that a world could possibly be is a way that some world is” (Lewis). He discusses in the beginning writing his book on time, and refers that to a certain possible world. Also, he states that he writes on the possibilities, not the impossibilities (impossibilia), but in some world he may be writing about the impossibilia. The bold writing says it all.

Lewis also adds that possible worlds perceived do not include worlds we make up. We may make worlds up in sleep, insomniac hallucinations, or narcotic hallucinations, and those are not the possible worlds because those are exaggerations and digressions of ideas of actual material things.

What do these possible worlds mean? To one that believes in this modal realism, it means (in my opinion, and others’) that sense data, or perceptions, denote material objects and/or reality in one way or another. Seeing the regular world one always sees, and then immediately seeing a world where all civilizations are wiped out, are both different worlds, meaning both are reality in one way or another. This is one answer for the argument stated at the very beginning ( are sense data representations of reality, or are sense data just images of the mind not connected to any reality). Modal realism states that all perceptions (not dreamed or hallucinated) are reality and can be of material objects.

So, one might ask, if I am perceiving one world (where monkeys run the world, and humans are the pets), how is the opposite world (where humans are the runners of the world, and monkeys are wild animals or pets) a real world at all? What we are perceiving at one instance is the only world actualized ( the succeeded form of a potential world). Another person besides me might be perceiving the same world, and maybe that person is perceiving a world not actualized to me. Because our perceptions are so different each person’s world is one world actualized while all the other possible worlds are, yet are in a potential state. The actualized potentialized understanding of all the possible worlds was kind of my understanding of all of this. It is also important to note that all possible worlds are not spatio-temporally connected. One world does not appear at one time, and another at a later time. One world does not exist in one space, and another world 6999 light years away. Spatio-temporal connections of the possible worlds are not existent.

To sum up the possible worlds in  modal realism:

• Worlds are not created by people- As in, one dreaming or hallucinating a round square (how that would be I have not a clue) is not of a possible world because this thing is not at all possible in any world.
• Worlds are not spatio-temporally connected-  Worlds are not spaced out in time, and are not located individually in space
• To conclude from the above, worlds appearing to each person (not dreamed or hallucinated) are worlds that happen to be actualized. All  other possible worlds not appearing to a person are potential, and still are.

To discuss more the argument that all perceptions are perceptions of reality, if one saw any blue animal ( a lion for instance)  in one world appearing to him, what that person is seeing would be real. This is because an animal can become blue if it needed to be (not in this case by itself, specifically if this was a weird world where people soaked animals in pools full of blue dye), and this is a possible world. Because of how this is incredibly possible, it is real.  If we try to take something incredibly outrageous and crazy from a dream or hallucination, like seeing a round square, a round square is not real or possible. A round square could not appear in a possible world, and is therefore not real or material in any way (something being real usually denotes it being a material object of some sort). A round square is just an example for outrageous crazy things that we make up sometimes that are not real even in the huge possible worlds of modal realism.

Look around. If you see something that cannot be logically possible then question the reality of your perceptions. But if you look around and cannot find one impossibility to be questioned, then your perceptions are real and material in the best sense of the words.

Thanks for the support, once again.