When talking about philosophical realism, how do philosophers define objects and their forms?

Question

Poorly versed in philosophical ideas, but I'm trying to get a grasp on some concepts discussed in The Last Superstition (2010), a polemical book on religion/theism by Edward Feser that an acquaintance recommended; in particular, I'm struggling with the second chapter, which provides a brief overview of Aristotelian metaphysics.

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My understanding is that a form is the nature of a thing, and is different from something's matter. Feser writes about how a blue rubber ball has the potential to be melted and molded into a door stop, for example, and the matter will persist through that change. However, the rubber will no longer have the ability to "roll" or "bounce".

1. Would this be an accurate description of how realists define what objects are? By what the matter has the potential to become/do? Would realists rely on spectroscopy, for instance, to define "blueness"? How would they say something is or is not "round" or "can roll on a flat surface" or "bounce"?

2. According to realists, are there infinite forms? My very crude understanding tells me this is the only way to reconcile this problem.

Answer 1

There is no single creature called the philosophical realist, nor position called philosophical realism. Rather, philosophers generally use the term "realism about X" to describe the position of believing that X is something that really exists. "Really exists" generally means that X is actual, and that that it is part of mind-independent reality. So, for example, realists about electrons think electrons are real things, not just features of our scientific models of atoms. Realists about values think that goodness and badness are part of the universe in a mind-independent way, and not just a feature of our way of looking at things.

Therefore, when philosophers say "realism," they generally have in mind some particular kind of realism, and so you might look into whether there is some kind of thing the existence of which your reading is deliberating about. Alternatively, it is possible that "realism" is used to describe the position of believing that there are some things that exist in reality in the universe, though that would be a little unusual.

Consequently, regarding your second question, realists in the general sense would not necessarily agree that there are forms in the platonic sense or any other sense.

Aristotelians, to take up your first question, understand the identity of objects in terms of their forms and also three other categories. Their forms are their shapes or structures. In addition to those, Aristotelians thought objects are characterized by their material (what they're made of), their origins (what thing or process produced them), and, most controversially, their purposes or ends (what they're for).

In your example, a blue rubber ball melted down will change its form but not its matter. It will become a different kind of object even though it consists of the same matter.