In article , Gary
Harnagel writes:

The existence of a benevolent civilization billions of years older than
ours wouldn't change YOUR worldview? Come ON!

Not in the least. Why should it? I wouldn't be surprised. The Earth
is about 4.6 billion years old, the universe about three times as old.
Civilization developed here, so I wouldn't be surprised if it did
elsewhere, but I don't know how likely it is; perhaps there is some
difficult bottlenect. It would be an interesting event, yes, but it
wouldn't change my basic worldview.

It WOULD change that of 99% of the world's population just if an advanced
civilization wore confirmed to exist on a planet around Tabby's star.

Why? How? What worldview is committed to the lack of extraterrestrial
civilization?

The odds of spontaneous life could be arbitrarily close to zero.
That we are here (necessary for this discussion to take place) has zero
commentary on the odds of spontaneous life anywhere else.

That's likely to be quite irrelevant:

https://en.wikipedia.org/wiki/Panspermia

Panspermia is a hypothesis, by no means proven.

I think it's pretty solid given evidence for extra-solar comets and asteroid
impact.

No life has been found there. Organic molecules, yes. But it is a huge
leap from there to panspermia. Suffice it to say that the most
scientists in the field are not convinced that panspermia is responsible
for life on Earth.

It
seems to me that we should be arguing intelligent life developed long
ago in the universe until refuted by evidence to the contrary.

Why should we assume anything?

Because we're human. It's what we DO.

Humans do many things; not all of them are correct.

Also, there is no way to disprove the existence of extraterrestrial
intelligence.

But there IS a way to confirm it, which was the mission of Kepler and will
be the mission of the Webb telescope.

Right (and contrary to what you wrote before): if you can find evidence
of extraterrestrial civilization, then you confirm it. The reverse is
not true: while absence of evidence is not evidence of absence, neither
does it mean that one should assume that extraterrestrial civilization
until proven otherwise, since one can never prove it otherwise.