If you actually had assumptions that made any sense and understood logic you would do better. However this isn't a question that can be answered by logic since we have no reality to base the assumptions on. It is like some ancient Greek sitting in his cave using his pure reason and logic to understand the nature of the universe. We tried that technique for a few thousand years and it got us nowhere. It has only been in the last few hundred years that the scientific method begin to tell us something about reality.
Why don't you spend more time proving that time began? Since you KNOW it did, you must have, or think you have, some evidence of the fact. Or was it just that it felt right?
Here's the argument again, since for the countless time you completely ignore the logic of it.
If one claims the past is infinite. That is the same as saying the amount of time that has already passed is infinite since the past is time that has already passed.
If this can't be understood then people have trouble understanding truisms. It is simply a truism that the past is time that has already passed.
If one claims the amount of time that has already passed is infinite they are saying it is an amount that has no limit or end.
This is just another truism, a definitional truism. An infinite amount of time is an amount of time that has no end. Infinite time in the future is time without end in the future. It is an amount of time that will never finish passing.
So if one claims the amount of time in the past is infinite that means they are claiming the amount of time that has passed before any present moment is an amount of time than never finishes passing.
Their claim is absurd. An amount of time that never finishes passing can't have already passed before any present moment.
It is like claiming the amount of time in an infinite future has finished passing.
It's a complete argument I haven't needed to change in a while.
It's been attacked with absurd objections, claims that the past isn't time that has already passed were made, claims that time doesn't pass were made, claims that time had no beginning were made, claims that infinite time can finish passing, claims that infinities end, and many other absurd claims were made.
But the logic of the argument remains. And the conclusion of the argument is that it is illogical to believe time in the past was infinite.
It is as illogical as to say that modeling infinite time with a line and an arrow somehow protects you from the logical consequences of saying time had no beginning.
Time with no beginning is an amount of time that can never finish passing. Just when we think it all has passed the arrow moves a little further and there is more to pass.
Infinite time is not like an infinite amount of fractions that are limited by a whole number. Infinite time is like the positive integers. An infinity that grows larger without end.
The past is one day plus another plus another. It is an ever growing infinity.