Last November, 80% of Denver voters rejected Initiative 300 to "adopt an initiated ordinance to require the creation of an extraterrestrial affairs commission to help ensure the health, safety and cultural awareness of Denver residents and visitors in relation to potential encounters or interactions with extraterrestrial intelligent beings or their vehicles"
While on its surface, Jeff Peckman's initiative is not unreasonable (more about that later), a quick perusal of his website (see http://extracampaign.org/) revels that he believes that extraterrestrials routinely visit the earth and that the government and its minions are involved in a conspiracy to keep the public in the dark. Rather than preparing for the possibility of an ET visit, Peckman's intention was to use a mandated extraterrestrial affairs commission to expose his belief in an ET cover-up.
I am often asked by non scientists if I believe in extraterrestrial life. From the scientific viewpoint, my answer is that there is no evidence for ET life. However, the existence of life beyond the earth is a testable hypothesis and therefore fits comfortably within the realm of science.
In the middle of the 20th century, Miller and Urey recreated in a glass vessel what were believed to be the conditions on the younger earth: water, methane ammonia and hydrogen in the presence of electrical sparks to simulate lightening. In a recent (2008) reanalysis of the data reported by Johnson et. al. in Science, these simple experiments showed that 22 amino acids - the basis of life on earth - were formed. Many other experiments since then have shown that amino acids can be formed under a variety of conditions both on the earth and in space. Thus, on the basis of our current knowledge of chemistry, astro-biology and extrasolar planetary systems, the existence of life is not only plausible but highly likely.
While there may be many worlds out there that have simple life forms, only a tiny fraction of them would evolve intelligent life forms. Even so, the numbers of stellar systems are astronomically large, so it is likely that alien intelligent life forms exist.
Some of my friends might argue that a belief in alien life forms is akin to a belief in God. Not so. I would argue that these two beliefs are significantly distinct. My arguments about the plausibility of ET life were based on our knowledge of terrestrial life, general science, and simple extrapolation. However, there is no scientific evidence for God. In fact, the Judeo-Christian God prohibits humans from putting Him to the test. On many levels, God can only exist through belief not through the scientific method. This does not imply that God cannot exist, only that there is no rational method for proof.
Given what we know, it is unlikely that we are alone in the universe.