Of course that claim is true; it is tautologically true. It says nothing more than "if a cause produces an effect, the cause must be able to produce that effect." But like most tautologies, it doesn't get us anywhere. It doesn't, for example, show that physical activities cannot cause mental activities.
But this wasn't even part of the argument I was asking you to respond to. Again, again, you are offering an argument that naturalism is false, but the claim I am responding to isn't "naturalism is false," it's "if naturalism is true, then rational thought is impossible." And the argument I offered against that claim was:
P1. [If naturalism is true, then] chemical actions (which are in themselves non-rational) cause mental states in people such as considering, judging and concluding.
P2. A person who is in the mental state of considering, judging and concluding is capable of doing those things well: that is, rationally.
C. Therefore, if naturalism is true, then non-rational chemical actions are capable of producing rational thoughts.
Do you dispute either premise? Do you claim that the conclusion does not follow, if the premises are true?