Thursday, August 22, 2019

Red cars and playdough

A red chunk of playdough needs to be red through and through. A red car need only be red on the outside. Peanut butter to be smooth must be smooth all the way through. But a mattress needs to only be smooth on the upper side to be smooth.

In other words, predicates like “is smooth” and “is red” apply to objects in different ways. A seemingly arbitrary decision needs to be made to how to apply them to a particular kind of object.

But perhaps this is only the case because chunks of playdough, cars, blobs of peanut butter and mattresses are not substances. Perhaps we can hope that for substances such decisions do not need to be made? But that hope is quickly dashed when we realize that a decision has to be made whether to call an electron a wave or a particle or both or neither, and that a decision has to be made which of a horse’s muscles are relevant to saying that the horse is strong (does it need to have strong eyelid muscles? tail muscles?).

Maybe when we descend to the level of applying fundamental predicates to substances, then the problem disappears. But that’s not clear. Position predicates seem to be fundamental but there is arbitrariness in deciding how to apply them to quantum objects when they are not in an eigenstate of position.

Perhaps where the arbitrariness disappears is when we consider cases where a fundamental predicate fundamentally applies to a substance. A fundamental predicate might non-fundamentally apply to a substance: thus, a dog might be negatively charged, and “is negatively charged” might be fundmental, but the dog is not fundamentally negatively charged—rather it is charged in virtue of mathematical facts about the overall distribution of fundamental charge properties throughout its body.


entirelyuseless said...

You might also need to consider how we decide to call a predicate "fundamental" or decide whether something "fundamentally applies." It may turn out (or rather it will) that the word "fundamental," like other words, applies to different things in different ways. This might cause problems for your standard of non-arbitrariness.

Michael Gonzalez said...

I don't think there's anything arbitrary about identifying an object as red insofar as it is relevant to the context. A red card is only relevantly red in the color of its numbers and symbols.

Now, I wouldn't extend this to particles; but that's because we're trying to determine what they are, not just some property about them relevant to particular situations (or, at least, physicists ought to be trying to determine what these things really are... it seems to me that the history of post-Bohr QM has been one of total denial about such basic aspects of what Physics is supposed to be after....). I would think deciding whether a particle is a wave or a particle is more like deciding whether a horse is an animal or a plant.