PRmerger:
Where else in the entirety of your experience have you ever seen something begin to exist which doesn’t have a cause?
Almost certainly nowhere. More relevant, however, is the question: Where in the entirety of my experience have I ever seen a universe begin to exist? Nowhere. I have no experience of such a thing.
My life-experience is incredibly narrow in terms of temporal duration, physical scale and type of substance. I have lived only forty-eight years (and for some of that time I was incapable of logical and reasoned thought). I can perceive things down to fractions of a millimetre and up to (arguably) millions of miles. Outside that range, and even within it, I have little or no direct personal understanding. I have experience of solid, liquid and gaseous substances made of the elements that exist at or near the crust of one planet. My experiences don’t even allow me to appreciate the nature of supercooled liquids such as glass. The range of pressures, temperatures, and properties of space-time that I have experienced is similarly incredibly narrow.
So it seems to me that I would be foolish indeed to make assertions about ‘whatever begins to exist’, because my experience about all of the things that may begin to exist is simply too small. I don’t believe that any other human alive or dead has or had sufficient breadth of experience either. If you insist on first-hand experience, I must reject premise 1.
To accept premise 1 as true seems to me to assert knowledge about all physical matter of all types and at all scales and at all stages of the life-cycle of our universe and even outside the space-time of our universe (assuming such a concept even makes any sense). I’m not prepared to assert such knowledge.
PRmerger:
What evidence do you have that the universe did not begin?
I don’t have any. But rejection of an argument does not equate to acceptance of the contrary view. I’m as yet unconvinced by the arguments that the universe definitely had a beginning
and by the arguments that it did not. I don’t think that any of us yet know enough about the origins of the universe. Hence I must reject premise 2.