> It's legal and perfectly reasonable for a human being to combine organic fuels with oxygen from the air to create energy and CO2.

Is there any line past which it becomes unreasonable?

> It would not be reasonable to allow machines to do that at unlimited scale without restrictions.

If the machines were a replacement for a damaged respiratory system in a human would it reasonable?

What about if the machine were being used by a human to do something else that was important?

Where is the line where it becomes reasonable?