Tuesday, May 02, 2006

The problem with enforcing strictly ridgid definitions is that it would be difficult to explain why the trashcan remains the same trashcan as time progresses.

If I cut a chunk out of the can, everyone will agree its the same trashcan. But the definition has changed, it has different molecules (there are less) and it now can be described as having a hole, whereas it couldn't before.


Blogger Undercover Sheep said...

Temporal parts! This is the answer. However, this answer runs into trouble when two objects are formed at exactly the same time and destroyed at exactly the same time. In theory, this makes the temporal parts argument weaker, but because it does not happen very often in reality, still offers some sort of explanation.

9:54 PM  
Blogger linford86 said...

Here's an alternative: don't include every property of the trashcan in the definition. Then, you don't run into any problems with having "changing definitions".

Also, in response to undercover sheep, why does the fact that two objects can be created at the same time and then destroyed at the same time cause problems for temporal parts? As far as I can tell, the temporal parts argument is not only consistent with Einstein's relativity but required by it. In any case, relativity requires objects - or physical things, whatever they may be - to have extension in time in basically the same way that they have extension in space. Of course, in physics, there is no problem with two things being created at the same time and then destroyed at the same time. In fact, the space-time diagram of a particle/antiparticle pair being created from a photon and then colliding back into each other to be destroyed only to create another photon requires that this is possible. For those of you guys who have taken Physics 143, you've probably seen that particular diagram (we just did Feynman diagrams right before our last midterm...)

1:34 PM  

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