ON THE MODALS III: Metaphysical Modality II

This week, we look at David Lewis’ theory that our world is one out of the infinite number of worlds in logical space. We ended the last point at the intersection of explaining modal statements in possible-worlds terms, i.e. we explain ‘I could have been a doctor’ as ‘In some possible world, I am a doctor even though I am not a doctor in this world’.

If clarity of language is the ultimate goal of philosophy as I argued in the first post, then using a term or entity that is not well understood to explain another term, kinda defeats the whole purpose, doesn’t it?! So it was that ‘possible worlds’ also needs clarification, or else, we know less about what we wanna say about modal statements than when we began explaining in possible-worlds terms. At this juncture, came Lewis in 1973 and in the following years with talks here and there about possible worlds being real and concrete worlds like ours, until he published a book in 1986, which contains a carefully argued explanation of what and how possible worlds are. The simple truth is that, no theory, if I may be so bare, has received much bludgeoning than Lewis’ modal realism. Let us then look at the main features of this theory to see why it was brutally attacked.

To start with, you already are familiar with the hypothesis that there are other worlds besides ours (perhaps from Kripke or from Everett, in the preceding post), and that our world is called the actual world and others worlds are called possible worlds. Now, Lewis also called possible worlds counterfactuals, which simply means ‘contrary to what actually obtains’. But ordinarily, a counterfactual is something of this form; “Had the Germans won WWII, the USA would not be world power today”. Counterfactuals pick on a situation which could have happened but did not, and create another situation out from it. I believe you can now see why Lewis called possible worlds counterfactuals. So let’s begin. According to Lewis, that possible worlds are counterfactuals is the only thing that differentiates them from our world. This means that, possible worlds are just as real and concrete as our world; there are people and trees, table and chair, space and time and every normal thing you are familiar with which are in our world. But there are also weirdos like ghosts, banshees, mermaids, unicorns, dragons, and many other creatures which are not normalcies in our world. This is crazy right?! Wait until you here more of how these creatures are generated.

Okay, if these worlds are concrete, why haven’t NASA discovered them, or are they identical with Mars, Mercury and the planets in our solar systems and in other solar systems? Lewis thinks they are not. He says possible worlds are not planetary bodies. They are not planetary bodies because we cannot cause anything to happen in a possible world. Take for instance, Mark Watney (Matt Damon) in The Martian went to Mars with his fellow astronauts in a spaceship and planted potatoes there. In simple terms, the movie portrayed that we can cause something to happen on planets. For Lewis, possible worlds are not like these, we cannot travel down there in any futuristic intergalactic space ship and we cannot telescopically view them either. The reason is that traveling and viewing are all causal relations, and we do not have causal power in possible worlds. If we have causal powers at possible worlds, then the position that possible worlds are counterfactuals of actual events, breaks down. WWII ended and we all know how it ended; the Nazi-Germans were defeated. But you had just made a counterfactual statement that had they won, the USA won’t be the world power that she is today, (perhaps you were trying to make a point or you were just saying, but it doesn’t matter). Now, we have said that what could have happen but didn’t, happened at a possible world. But counterfactuals are not just saying what could have happened; they create distinct situations out from what could have happened. So,now suppose that a possible world, called W (or whatever you want, it doesn’t matter) is a world where the USA is not the world power. If we say that we have causal roles to play in possible worlds then we are saying that the USA is not the world power in W because the Nazi-Germans won WWII in our world, and you and I both know that they didn’t. Thus, whatever is a cause in a world only has effect in that world. Not so crazy after all, huh?!

Another reason why causes and their effects are within worlds is that there can be no space or time relations between any two worlds. Take your car and yourself; there is no part of your car that is a part of you and no part of you that is a part of your car. We can say then that you are spatiotemporally (space and time) disconnected from your car. Worlds are disconnected from one another in this way. There is no part of our world that is a part of W and no part of W that is a part of our world. We can say then that worlds are causally, spatially and temporally disconnected from one another. And from what we know about planets they are causally, spatially and temporally connected to our world and to one another. We can cause something to happen there (causally), we can travel down there (spatially) and we know what time it is there or how fast time runs there (temporally). If worlds are disconnected in these ways, then I cannot be in more than one world. I would not insult your intelligence by trying to explain this; it simply follows from what I said earlier about your car and you. Okay, I take that back. I can’t resist the temptation to explain; it is just too interesting a theory. Hahaha‼!

Since you are not part of your car and your car is not part of you; if your car is in the garage and you are on the sofa watching the sixth episode of Game of Thrones season 6, then your car is ‘there’ and you are ‘here’. You cannot also be ‘there’ and be ‘here’. Thus, you cannot be in two places at the same time. We can say then that every physical object is spatiotemporally bound. If I am here, then I am in no other place than here. End of the matter. So, if you are part of this world, then you are part of this world and you cannot be part of another world. But Lewis has a trick up his sleeve. He says, we have counterparts at possible worlds. Our counterparts are persons who have very close similarities with us, but who are not us. Even sci-fi writers are not that dumb to present two individuals who are from different universes completely the same persons. There are always some minute differences. Recall my example of Barry Hallen in the preceding post. The first world he and his friends went to, he was not the flash in that world. That is the kind of dissimilarities I am talking about. He shared very close similarity with Barry but he wasn’t completely similar to Barry and so he wasn’t Barry. In this way, I am not the person that is a doctor in W but my counterpart. 

You might have noticed that the whole theory of possible world hinges on what actually happens, and that should make our world, the actual world superior to other possible worlds. For Lewis, this is not the case; no world is superior to another; all worlds are on a par. I speak for many if I say this feature is the one that gave me so much trouble wrapping my head around. But once I understood why Lewis says so, I immediately saw that nothing could be more correct and I hope my explanation does the same for you. Lewis thinks that we should explain ‘actual’ in the same way we explain ‘here’, ‘now’, ‘I’ and all other indexical terms. When we use ‘here’ or ‘now’ or ‘I’, what we mean depends on where we are. If I am in the car, here or now means ‘in the car’, if I am on the sofa, they mean ‘on the sofa’. Also, ‘I’ always means ‘the speaker’. In this way, ‘actual’ means ‘where the speaker is’. So, we call our world actual because we are the speakers and we are in this world. In the same manner, your counterpart in W will think his world is the actual world because he is the speaker and he is in W. In this way, that our world is the actual world doesn’t make our world any more superior than W.

I promised to keep things short, so I fear I must stop at this point even though there are few more things to say about Lewis’ modal realism. For those who have been captivated by Lewis I apologize. In the next post, I begin with the last feature which time has made me cut out in this one. The feature will be about how the persons and things that populate possible worlds are generated. Even with the features I have discussed here, you must have begun to see why Lewis’ theory was frowned at even by fellow philosophers. After I talk about the last feature in the next post, I quickly discuss the versions of the possible world theory that claim to offer the benefits of Lewis’ theory but without the cost. The cost, as you must have discerned, is that his theory is so far away from commonsense. Well! That is all for now, see you next week.