Comment by pengstrom
I think the fact that the initial _size_ of the recursion can be arbitrarily large is where infinity comes in. No matter your resources, there might be (must be?) a recision problem that's too large, that requires too many steps.
I think "recursion" simpy said, allows for algorithms which end as much as "not ending algorithms".
but in practice, an algorithm has gotta end, otherwise it's not very useful. I think some academics would go as far as insisting a function or process which never ends is not even a proper "algorithm"; but I digress.
recursion does allow us to "reach the infinite"; however, philosophically, we can only ever grasp the finite.