Suppose you have a black box. It has two openings, one labeled "Questions" the other labeled "Answers."
No matter what you put into the "Questions" slot, something will come out of of the "Answers" slot. Whatever the "Answers" output is, it is a complete answer to the "Questions" input question.
This is true even if the "Questions" input is not a question. To be clear, anything can be put into the "Questions" slot and will produce a complete answer from the "Answers" slot.
This means that even output from the "Answers" slot could be input into the "Questions" slot, and thereby produce it's own answer.
Again the truth of these answers will always be as reliable as the truth of the answer to the question "If I have one apple and someone else gives me an apple, how many apples will I have?" is "Two apples."
This is even true of questions that are unanswerable, like the halting problem or something of that nature. The black box will never the less produce an answer. The black box is not a computer and is not limited by the limits of computation.
Now, imagine that you do not have access to the "Answers" slot. The answers are being produced to whatever question you are feeding into it, but you cannot see them or know what they are.
That would be frustrating, but you would know for certain that there was an answer, even if you could not see it.
Suppose now, that for some questions, you can figure out the answer yourself. Without observing what the output of the black box is, you can still know what the box will output anyway. This empirical or grammatical fact. Things that can be known through observation or reason.
We have access to these facts, although the black box will not confirm them.
There are other questions that we cannot figure out the answers on our own. Any number of answers could be correct, all of them could be, or none of them could be. We just can't tell because we can't see what the output is.
These are metaphysical questions, or rather, these are the anxieties that we attempt to address with metaphysical questions. Here I mean questions like: "Why is there something rather than nothing?" "What is the mind?" "What is the essence of the good?" "Why is the world as it is and not some other way?" "Is the world determined entirely materially or are there also volitional causes?" "What is a volitional cause?"
The only way to answer these questions would be to understand the workings of the black box.
But to understand the workings of the black box we would need to either a.) open the box and observe its mechanism or b.) reverse engineer its mechanism by seeing how it gets an output from a given input.
We can do neither of those things.
This is a model of the god-machine.
From this model we can learn various things about the god-machine
1.) It is impossible to ask meaningful questions about the output of the god-machine because any answer will be arbitrary and without any grounds for belief beyond the temperament of the believer.
2.) The god-machine cannot not exist because it is defined as the point beyond which inquiry cannot proceed. That point exists necessarily because there are questions of metaphysics that can neither be observed or reasoned about, which are the only species of questions that can be answered without appeal to the output of the black box. The god-machine's enigmatic existence is therefore a necessary truth.
3.) It is impossible to know what the god-machine is because its exterior is entirely opaque. The input god-machine is the limit of inquiry and it's own workings are past that input and cannot be interrogated.
4.) None of these things that we can know about the god-machine are particularly interesting because they are tautologies.
5.) Because the god-machine represents the limit of inquiry, it must therefore be the final answer of any regression of causes or questions because nothing beyond its limit can be interrogate.
6.) The god-machine exists everywhere in the substance of the universe as the final answer to the question of what matter energy space and time are, and also therefore cannot exist anywhere because those things are matter and energy and space and time and are definitely not the god machine as defined above.
7.) Such a thing is a paradox and cannot exist.
8.) Because it must exist, a paradox is true, therefore paradoxes do not preclude existence.
9.) This leads to vicious regression about paradox and logical necessity the resolution of which is beyond the limit of the god-machine.
10.) Therefore it is a sufficient answer to any metaphysical question to simply point to the god-machine and shrug.