Sometimes the probability of the existence of an alien society with which we might make contact is discussed in terms of something called "The Drake Equation."
In 1961, the National Academy of Sciences asked the astronomer Frank Drake to host a scientific meeting on the possibilities of “interstellar communication.” Since the odds of contact with alien life depended on how many advanced extraterrestrial civilizations existed in the galaxy, Drake identified seven factors on which that number would depend, and incorporated them into an equation.
The first factor was the number of stars born each year. The second was the fraction of stars that had planets. After that came the number of planets per star that traveled in orbits in the right locations for life to form (assuming life requires liquid water). The next factor was the fraction of such planets where life actually got started. Then came factors for the fraction of life-bearing planets on which intelligence and advanced civilizations (meaning radio signal-emitting) evolved. The final factor was the average lifetime of a technological civilization.
Sometimes this kind of wild speculation and guesswork is called "science."