The Cosmological Argument and Free Will

[Mudhammam]

I'm still not sure why it seems to be sound when applied to anything, let alone the totality of existence (or any specific area). Mechanical issues with the statements. Are we aiming more for a "non-existence doesn't exist" sort of thing or a "that which is non-existent does not exist"?

I take it to mean that non-existence as a stand-alone concept does not change; change requires a "something" to act upon; a "something" for which change can be said to apply.