In the same way that you don't know that there are machines that don't have makers.
However, in the vastness of the machine world, the evidence that all machines have makers is so great, that you would have a difficult time finding a machine without a maker.
I'll help you. There is that ancient Greek machine that turns out to be the oldest computer in the world - http://www.pbs.org/wgbh/nova/ancient/ancient-computer.html - that was found on an ancient Greek galleon. Just because it was found there, on a sunken Greek galleon, doesn't mean we know that it had a maker. But try to tell that to any scientist, and they will laugh you right into a funny farm.
This is the same argument as ''everything is designed'' which I already debunked. You told me to look for the definition of machine: ''an apparatus consisting of interrelated parts with separate functions, used in the performance of some kind of work:'' Now if the universe can be a machine, then so can a volcano, for example. Now how do you know a volcano has a maker? We don't. We only know ''machines'' have makers because those makers are humans, all the machines that have makers are humans, that doesn't prove god or that all machines have makers, it only proves, in any case, that all machines have human makers.
Consider AI. It is a machine made by mankind. Yet it can teach itself to play chess better than a human, even in ways that a human can't match. Our crude AI isn't really alive, doesn't really have sentience. Yet it acts in ways that seem uncontrolled... at least as far as we are concerned. But the work that it does is not controlled directly.
AI is a machine made up of many smaller machines, doing work that is not controlled by us directly - not even entirely understood by us. Yet the Master Machine Maker understands every, last erg of energy and force in a volcano, via cause and effect. He set it up. He also understands every last working of our AI. None of this means that He has to focus on all of it all the time, with the essence of His "I AM."
You have in no way debunked the idea that everything is designed. What you are doing is debunki9ng yourself. Soon you will be gone forever... if you do not change and take hold of the offering of eternal life from God.
You didn't answer at all here. I asked you how do you know that everything is designed or made by a sentient being. Yes we know our machines are designed by us, obviously just like we know a watch or a chair is designed by humans because nature does not produce such things. You are claiming that trees, rocks, planets, everything is designed by something else, my question is, how do you know?