By circular motion, you either mean a causal series that loops back onto itself (last member causes first member) or a circular explanation (explaining the explanandum with more explanandum) like the one above.

Both are compatible with the first way.

A causal loop of derivative instruments would still a need a prime mover to derive their motus or causal powers. Otherwise, your friend is saying that the gears can move without a motor provided that they are in a circle. We still need a source of actualization outside the loop to get the gears or derivative instruments going. You can put the instruments or gears in a circle, net, stack them but without a prime mover or motor, there will be no effect. You still need a prime mover or a motor to actualze their potency.

Explaining the explanadum with more explanadum is obviously avoidong the question since all it does is introduce new derivative instruments or more "gears".

As for the example of gravity: The potential gravitation of the smaller mass to  the bigger mass is actualized by the spacetime curve which is actualized by their masses which is actualized by the Higgs boson and so on.

Camoden wrote:

I agreed with the first part and that wasn’t so much my issue. I think the crucial difference is whether there is a possible capacity for actuality in operation given the constituents. I agree in the gear series there isn’t. The last part is really helpful however, although I didn’t suppose the objector was trying to focus on anything other than the mundane aspects of it. Sorry if I was really unclear about what I was trying to convey.

Thanks and God bless you,

Cameron

It would apply to all essentially-ordered series.  

I honestly wish I could delete this whole thread. I had just gotten up and thought that there was a lot more to this objection than there was. This is literally just as much an example of mutual manifestation as almost any physical example would be.

Thanks for the responses,

Cameron