Exactly the opposite. Neither you nor I know how common extraterrestrial intelligence may be.
All we know is how vast the universe is. And even our own galaxy is mind numblingly large.
To claim that absence of evidence, especially when the search so far has been infinitesimally small and restricted, is evidence of absence of other intelligences is laughably false. Heck, it is only within the last century we have established that there are not other intelligent beings on Mars and Venus, and we still have no idea if their may be other life within our own solar system, or past life on Mars.
Whoops, that reply was meant for another thread.
I never made such a claim. All I am claiming is that I don't believe there are other intelligences out there because I have seen no proof that there are. And yes, its a fine logical point. When and/or if such evidence shows up, I will likely change my mind. But until it does, I believe what I believe.