There are two hundred BILLION stars in our home galaxy, and even more galaxies in the the observable universe. The staggeringly incomprehensible numbers involved, lean towards a universe teeming with life - advanced and otherwise.
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To counter those big numbers, the available evidence points to the probability of life, especially intelligent life to be extremely small.
Absence of evidence is not evidence of absence.
Humankind has only just begun taking its first tentative steps outside its own front door. In a universe as big as ours, it's no wonder we haven't yet discovered lifeforms elsewhere. We've barely begun exploring our own back yard.
Only when our technology has advanced sufficiently to enable us to easily explore other star systems, will we be able to gather enough evidence to answer the question of alien life.