At Big Think, philosopher Shai Tubali rehearses all the reasons we should suppose that there is life out there — the vastness and variety of the universe, the fact that our search has hardly begun, the possibility of completely unknown biochemistries — but then he admits,

However, these thrilling reasons for scientific excitement shouldn’t distract us from a sobering truth: This is still a leap of faith. The question of whether we are alone remains one of science’s greatest enigmas. As Professor David Kipping aptly points out, the data paints a tantalizing picture — just as compatible with a Universe brimming with life as it is with one where we stand solitary under the stars. To insist there must be life out there, he reminds us, is to trade evidence for optimism. The most honest answer to this cosmic mystery is a simple, awe-filled: “We don’t know.”

“What if we’re alone? The philosophical paradox of a lifeless cosmos,” January 31, 2025

Then there is the possibility that we are effectively alone:

And even if other civilizations exist, we may be forever separated by the vastness of space and time. Our attempts to listen to the stars have met only with haunting silence. Civilizations might arise and vanish like sparks, flickering out long before their signals could traverse the galactic void. The distances are staggering — light itself takes millennia to cross the nearest stars — and our technology for interstellar travel is more fiction than fact. To make matters worse, the Universe’s accelerating expansion drags galaxies further apart, locking us into a kind of cosmic isolation. In the grandest sense, we might be effectively alone — adrift in a magnificent yet uncaring sea of stars, waving a signal no one will ever see. “What if we’re alone?”

Author of many books, including Cosmos and Camus: Science Fiction and the Absurd (Peter Lang, 2020), Tubali thinks we should face the possibility that we are alone:

Facing cosmic loneliness head-on might be our most empowering choice. If we are truly alone — no reflective, self-conscious extraterrestrial companions as far as we can tell — it’s time to stop waiting and embrace this Universe as ours. Constantly yearning for other life forms or hoping for redemption from this solitude risks avoiding responsibility. Would a bustling galactic neighborhood really make our existence more meaningful? Philosopher Thomas Nagel argues that even a role in some grand cosmic enterprise might fail to give us what we truly seek. In the end, with or without the fireworks of “others,” we are the naked human, standing in an unfathomable Universe, with no one to make choices for us. “What if we’re alone?”

All of this, of course, overlooks the overwhelming evidence of the fine-tuning of the universe and of Earth for life, which suggests a cosmic Mind underlying it. In that case, we are never, strictly speaking, alone. Then the quest for extraterrestrial life remains a reasonable pursuit if we want to find out more about our universe. But not so that we won’t be alone.