Dumb question about modal logic

[rizdek]

There is a dumb question thread in the science forum. This is a dumb question in logic.

I guess I understand that the ontological argument for god makes use of modal logic. And I guess modal logic has something to do with imaging worlds and whether things could happen/exist, must happen/exist or cannot happen/exist.

I don't want to ask the pros and cons of the ontological argument for god. And I don't really want someone to try to explain to me the ins and outs of modal logic...that's my job to learn and I am trying. But rather, can someone give an example of what other practical but uncertain issues are argued for or against using modal logic? I'm not looking for a simple and obvious example like the one below to demonstrate the argument form, but where else (besides the god argument) does the argument lead to debates because of uncertainty about the issue(s) being argued? Thanks.

I have been trying to read up on it, but find the discussion at sites like wiki, for example, to be odd. If someone really doesn't know what modal logic is, then they aren't going to get it by reading wiki. The article is so full of logic speak that one would need a pretty good background to understand the discussion. And if they have that background, they probably know enough about modal logic that they wouldn't seek a deeper understanding by going to wiki...of course I might be wrong given I don't understand what was written.

I found this explanation of how modal logic might be useful:

Why is modal logic useful?

Classic logic is great for mathematics, but for the analysis of daily language and arguments, it lacks certain operators. There are many sentences that you can't express in classic logic that can be expressed in modal logic. Example: "I may get burned if I lie in the sun for too long". In classic logic, you can say: "I get burned if I lie in the sun for too long", but you can't express the possibility of getting burned. In classic logic, it's either true or false. In modal logic, you can also express the possibility or impossibility of a proposition being true or false.

from: http://philosophy.stackexchange.com/questions/5929/what-is-modal-logic-for

But, I'm thinking really? That doesn't seem like an example of how it is useful? It might demonstrate, but it's so obvious that it doesn't seem useful.

 

[Wiploc]

- If you cross the street without looking both ways, you may get hit by a car.
- You don't want to get hit by a car.
- Therefore, you ought to look both ways before crossing the street.

It is, like you say, obvious. And it is overwhelmingly useful; you rely on modal statements all the time.

Systematizing modal logic, making it a rigorous field, is hard. I don't know what use that is. It seems to me that the entire virtue of the modal cosmological argument is that it is sufficiently confusing that people can be confused by it if they want to be.

 

[rizdek]

It seems, then, that modal logic is very much used in every day life...we just don't think of it in "modal logic" terms. It allows us to accommodate uncertainty, to err on the side of safety, to make decisions with less than complete information and even enjoy life as in, "I'm not sure I will like this new dish, it's possible I might like it, so I'll try it and yummy!" Yes that has double meaning, but I was thinking a food dish.

Perhaps also without using the term modal logic, the whole field of risk analysis where folks debate how much to weigh this or that factor is a form of modal logic?

Thanks.

 

[StarryNight]

well being necessarily good for owner, therefore transworld ethics possible , albeit basic. contingent unto others so love and hate possible virtues for them given apt context. eg i am aiding or harming their well being.

 

[DBT]

Here's an interesting criticism of the use of modal logic in philosophy;

Quote:
''There are a number of reasons why I feel that modern philosophy, even analytic philosophy, has gone astray - so far astray that I simply can't make use of their years and years of dedicated work, even when they would seem to be asking questions closely akin to mine.

The proliferation of modal logics in philosophy is a good illustration of one major reason: Modern philosophy doesn't enforce reductionism, or even strive for it.

Most philosophers, as one would expect from Sturgeon's Law, are not very good. Which means that they're not even close to the level of competence it takes to analyze mentalistic black boxes into cognitive algorithms. Reductionism is, in modern times, an unusual talent. Insights on the order of Pearl et. al.'s reduction of causality or Julian Barbour's reduction of time are rare.

So what these philosophers do instead, is "bounce" off the problem into a new modal logic: A logic with symbols that embody the mysterious, opaque, unopened black box. A logic with primitives like "possible" or "necessary", to mark the places where the philosopher's brain makes an internal function call to cognitive algorithms as yet unknown.

And then they publish it and say, "Look at how precisely I have defined my language!"