I'm sorry, but I must be dense. I see two issues here. First issue is that any change requires an existing (actual) cause, for something cannot come from nothing. Thus the cause of the food going from cold to hot is something actual, the microwaves. OK. But, second, according to Feser, not only must the cause of the change from cold to hot exist prior to the change, and bring about the change, but it also must have in actuality hotness: what causes hotness must itself be hot. Based on your remarks, either I have misunderstood Feser or Feser is confused about Aristotelian causality.

I don't have a problem with the notion of a sustaining cause, whose activity would be simultaneous, What I question is the notion of a hierarchy of such causes. In addition, both his notion of initiating cue and sustaining cause relies on this Potentiality/Actuality model, which is what I am questioning. The example that comes to mind is a microwave oven. Microwaves cause something to go from cold to hot. On his model of causality, this is because the microwaves are actually hot!

Addendum:
The problem I have is with Feser's (Aristotle's and Aquinas's) view of causality. I'd like to think that it is not just a disagreement about the meaning of the term 'cause', but rather about what account we can give of the causal relation, viz., what makes the proposition ^A causes B^ to be true?

Thanks andrewk. I posted my issue there, but will do so here as well.

I have several problems with Feser's argument.
1. His Principle of (Aristotelian) Causality: Every change is a change from potentiality to actuality brought about by something with the actuality in question.
2. His Principle of (Hierarchical) Sustaining Causality
3. His claim that the existence of anything is the result of the actualizing of the potential to exist by something already actualized as existent.
4. His claim that anything that already existing cannot continue to exist with out something sustaining that existence, continually actualizing the (so-called) potential for existing.
5. His claim that while there may be an infinite chain of (temporally extended) initiating causes, there can not be an infinite chain of simultaneous sustaining causes.

What I would like to know is whether there are any good arguments against these theses, especially #1 and #3. #3 seems to treat existence as a property that something may have as either potentially or actually, similar to the potential for hotness. And that just as something that is actually hot "activates" the potential for hotness in another object, so to something that exists activates the potential for existence in another.

The problem I have is with Feser's (Aristotle's and Aquinas's) view of causality. I'd like to think that it is not just a disagreement about the meaning of the term 'cause', but rather about what account we can give of the causal relation, viz., what makes the proposition ^A causes B^ to be true?

I have several problems with Feser's argument.
1. His Principle of (Aristotelian) Causality: Every change is a change from potentiality to actuality brought about by something with the actuality in question.
2. His Principle of (Hierarchical) Sustaining Causality
3. His claim that the existence of anything is the result of the actualizing of the potential to exist by something already actualized as existent.
4. His claim that anything that already existing cannot continue to exist with out something sustaining that existence, continually actualizing the (so-called) potential for existing.
5. His claim that while there may be an infinite chain of (temporally extended) initiating causes, there can not be an infinite chain of simultaneous sustaining causes.

What I would like to know is whether there are any good arguments against these theses, especially #1 and #3. #3 seems to treat existence as a property that something may have as either potentially or actually, similar to the potential for hotness. And that just as something that is actually hot "activates" the potential for hotness in another object, so to something that exists activates the potential for existence in another.