Summary |
Two
characteristics distinguish quantities from non-quantitative
properties and relations. First, every quantity is associated with a
class of determinate “magnitudes” or “values” of that
quantity, each member of which is a property or relation itself. So
when a particle possesses mass or charge, it always instantiates one
particular magnitude of mass or charge -- like 2.5 kilograms
or 7 Coulombs. Second, the magnitudes of a given quantity
(alternatively, the particulars which instantiate those magnitudes)
exhibit “quantitative structure”, which comprises things like:
ordering structure, summation/concatenation structure, ratio
structure, directional structure, etc. We often represent quantities
using similarly-structured mathematical entities, like numbers,
vectors, etc. Classic
debates about quantities concern attempts to give a metaphysical
account of quantitative structure without appealing to mathematical
entities/structures. Other questions include: How do quantities play
the roles they do in measurement, the laws of nature, etc? Are a
quantity's magnitudes fundamentally absolute (like 2.5 kilograms) or
comparative (like twice-as-massive-as)? |