Why Something rather than Nothing? The 'Why not?' Response

According to a presumably apocryphal story, Martin Heidegger asked G. E. Moore, "Why is there something rather than nothing?" Moore replied, "Why not?" A reader finds the 'Moorean' response cheap and unphilosophical. Let's think about this.

Suppose we ask a related but more tractable question: Why does the universe exist? and we get the response: Why not? Why shouldn't it exist?  Charitably interpreted, the response amounts to the suggestion that the question is gratuitous or unmotivated or unnecessary in the sense of unneeded.

Some explanation-seeking why-questions are gratuitous. (It is worth noting that grammatically interrogative formulations such as 'Why does anything at all exist?' might be used merely as expressions of wonder that the, or a, universe exists, and not as requests for an explanation. Here we are concerned with ultimate explanations.)

Suppose it is 110 degrees Fahrenheit.  I walk into your house where the temperature is a pleasant 80 degrees. If I were to ask why the air conditioning is on, you would be puzzled. "Why shouldn't it be on?"

But if your house were a miserable 95 degrees and I asked why the air conditioning was not on, or why it was so bloody hot in there, you would give some such answer as: "My A.C. unit is on the fritz; the repairman should be here in a couple of hours."

My first question is gratuitous; my second question is not. Some things need explaining; other things don't need explaining. 

Perhaps it is like that with the universe. Why should anyone think that it needs an explanation in terms of some item transcendent of it such as the One of Plotinus or the God of Aquinas? 

I assume, quite reasonably, that the universe U is modally contingent. Thus it does not exist of metaphysical necessity, the way God exists if he exists; nor is U's existence metaphysically impossible.  U exists, but it might not have: its nonexistence is possible.  That is to say: U exists, but its nonexistence is not ruled out by the laws of logic or the laws of metaphysics.  It exists, but its nonexistence is neither logically nor metaphysically impossible.

But if x is modally contingent, 'contingent' for short, it does not straightaway follow that x depends for its existence on something. It is a mistake to conflate modal contingency with contingency-on-something. That is an important conceptual/semantic point. 

So it might be like this: U exists, and exists contingently, but it exists without cause or reason or explanation. If this is the case, then we say that the universe exists as a matter of brute fact. The factuality of the fact resides in its existence; the 'brutality' in (a) its contingency and (b) its lacking a ground, cause, reason, explanation.

I conclude that one cannot argue a contingentia mundi to a prima causa without a preliminary demonstration that our ultimate explanation-seeking why-question is not gratuitous. Before one can mount a cosmological argument from a contingent universe to a transcendent Cause, one must show or at least give a good reason to think that the universe needs an explanation.

In my published work on this topic I argue that contingent particulars, taken by themselves as "independent reals" are contradictory structures. But they patently exist, and nothing can exist that is self-contradictory. So there must be something transcending th realm of contingent particulars to remove the contradiction. Now I cannot go into the many details here and fill in the steps in the argument, but the main point I want to make, in answer to my reader's query, is that it is not unphilosophical to take seriously the 'Why not?' response.

One needs to be able to show that the question, Why does the universe exist? is not gratuitous.