In article , (Eric
Flesch) writes:

On 30 Dec 2017, Gary Harnagel wrote:
It is quite unreasonable to assume that in all the universe we are the
first. In fact, it is unreasonable to assume that a civilization like
ours didn't develop billions of years ago.

Ding! Wrong. A first one is a requirement, therefore it cannot be
unreasonable to posit it in the absence of knowledge of any other.
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.

I'm a bit confused. Perhaps you mean that since SOME civilization has
to be the first, one can't disregard that we are the first.

Whether it is likely that we are the first, and whether it is likely
that we are not alone, are other questions.

Opinions vary greatly on the probability of extraterrestrial
civilizations. While life might be common, it could very well be that
intelligent life is not. For well more than half of the history of life
on earth, the most advanced organisms were similar to algae. Since the
Cambrian explosion occurred only 600 million years ago, it appears far
from inevitable. Similar arguments apply to human civilization, which
is very, very recent; if it took so long to arise, it could easily have
taken much longer.

Until relatively recently, the number of humans on Earth was not that
large, and the amount of geological time occupied by humans very small
compared to other times. Could an intelligent but non-technological
species at a level of intelligence similar to humans have arisen
sometime in the past but left no fossil or other record?