of the
    sort whose finite axiom set has been written down.

JA: 4.  Ergo, sets and their elements are not physical objects.
 
JA: Now, I am perfectly well aware that we very often speak as
    if physical objects could be sets, or the elements of sets,
    but that just tells me that we very often speak loosely.
 
JA: No news there.
 
JA: The confusion arises, I guess, from the fact that we very often
    use mathematical systems in the description of physical systems.
    And so I would have to classify