I’m still left with the same question: how do you distinguish between worlds where the only difference is the facts and not the laws.
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From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of sowa@xxxxxxxxxxx
Sent: 26 July 2011 12:13
Subject: Re: [ontolog-forum] intangibles (was RE: Why most classifications are fuzzy)
> I am left wondering what it is you would use possible worlds/Dunn's
> semantics for. It seems that you are expecting different laws of physics to apply.
No. I was just making the point that modality depends on laws. For practical applications, I would assume the same laws of physics in all worlds. That defines the meaning of 'necessary' and 'possible' as physical necessity and possibility.
But we could also have many other kinds of modality, such as engineering possibility, which would depend on the available technology. In the 1940s, for example, it was impossible to build a computer with transistors. Today, it would be economically impossible to build a computer with vacuum tubes, because it would be prohibitively expensive to build a factory that makes the kinds of tubes we would require.
The laws could also be the laws of different countries, which can make certain designs permissible in one country, but illegal in another.