StephenLawrence - 12 June 2012 04:34 AM

The difficulty is coming up with objective parts.

I think this is made particulary clear when thinking about temporal parts. So you are spread out from birth to death and we can divide you, over time, into parts.

But how could those parts be objective? I might pick 3 second divisons, or 3 year divisions, or daily divisions, but in each case I’ve drawn the lines between the parts.

What are the objective lines between your temporal parts?

Interestingly, this is the same question I asked of David Lewis many years ago. He gave, IMO, the right answer: there are as many divisions among temporal parts as there are among spatial parts. IOW the temporal line is the same as the real number line: it is a continuum with an uncountable infinity of points along it.

Though of course once you get below Planck’s Constant, the divisions no longer make any physical sense.

The more general question about ‘objective parts’ can be answered by reference to ‘natural kinds’. If there are natural kinds in the world, there are objective parts, and our usage of those kind-terms ‘cuts nature at the joints’ (as I think it was Plato who said). If there are no natural kinds, then all divisions of reality into parts are conventional in nature.

But even if such divisions were conventional (e.g., that any such division would be as good, true or useful as any other), that would not change the fact that reality is divisible into parts. The latter is incontrovertibly true.

dougsmith - 12 June 2012 04:52 AM

StephenLawrence - 12 June 2012 04:34 AM

The difficulty is coming up with objective parts.

I think this is made particulary clear when thinking about temporal parts. So you are spread out from birth to death and we can divide you, over time, into parts.

But how could those parts be objective? I might pick 3 second divisons, or 3 year divisions, or daily divisions, but in each case I’ve drawn the lines between the parts.

What are the objective lines between your temporal parts?

Interestingly, this is the same question I asked of David Lewis many years ago. He gave, IMO, the right answer: there are as many divisions among temporal parts as there are among spatial parts. IOW the temporal line is the same as the real number line: it is a continuum with an uncountable infinity of points along it.

Though of course once you get below Planck’s Constant, the divisions no longer make any physical sense.

The more general question about ‘objective parts’ can be answered by reference to ‘natural kinds’. If there are natural kinds in the world, there are objective parts, and our usage of those kind-terms ‘cuts nature at the joints’ (as I think it was Plato who said). If there are no natural kinds, then all divisions of reality into parts are conventional in nature.

But even if such divisions were conventional (e.g., that any such division would be as good, true or useful as any other), that would not change the fact that reality is divisible into parts. The latter is incontrovertibly true.

Thanks Doug, interesting.

How did you get to ask David Lewis questions?

Stephen

Isn’t the sorities paradox just an example of the contiunuum fallacy?

Austin Harper - 12 June 2012 05:59 AM

Isn’t the sorities paradox just an example of the contiunuum fallacy?

Yeah, you’ll see on your wiki citation, they’re basically different names for the same thing.

StephenLawrence - 12 June 2012 05:35 AM

How did you get to ask David Lewis questions?

He was one of my professors.

dougsmith - 11 June 2012 11:36 AM

CuthbertJ - 11 June 2012 10:15 AM

... my question really is roughly the same as Plato’s Forms notion.

You’ll have to explain that one to me.

It’s pretty heady stuff, but my understanding is that Forms refers to the ultimate reality or templates that exist, that particular physical things mimic or are reflections of.  So the thing that makes a person different from a rock is that each derives from a different form.  IMO it was Plato’s way of thinking about the same thing we’re discussing here…parts, wholes, differences between things, etc.

Here’s a link to a nice wiki article.  http://en.wikipedia.org/wiki/Theory_of_Forms

dougsmith - 11 June 2012 11:34 AM

CuthbertJ - 11 June 2012 10:05 AM

You could BE the Universe itself, as in “conscious beings are the way the universe contemplates itself”.

I’m not so egotistical as to think myself identical to the entire universe.

Also, the entire universe includes Jupiter, which is a bit too large to fit in my stomach.

Hmmm, I don’t find that egotistical at all.  Now if I went on to say, and by the way since I’m the universe I’m going to create a black hole in your backyard if you don’t give me $100, then ya that’s egotistical!  BTW, I recall the idea of us being the way atoms think about themselves as coming from Carl Sagan…definitely one of the most humble people who ever lived.