A question that gets asked often by skeptics, not without some irony, is why do we seem to often jump to the conclusion that a UFO is connected to extraterrential beings? By definition, any unknown object seen flying is a UFO, and as some people point out, this could mean an alien spaceship just as much as it could refer to a frisbee someone else threw far away and which you can see but not recognise. Or, perhaps more likely, it might simply be a human aircraft rather than an alien one, and any governmental secrecy is further explained by said aircraft being of the military type.
Truth be told, ufologists may sometimes be too rash in declaring a UFO sighting to be proof of extratterestrial activity.
There are believable sightings of UFOs going back at least to the 19th century. Before that, there may still be reports, but far too little data to judge them from. However, it wasn't until the mid 20th Century that the default reaction to UFOs was to assume they were extraterrestrial.
Modern ufology has a birth date: June 24th, 1947. Pilot Kenneth Arnold is flying his plane in the Pacific North West. The weather is good and the sky clear. Unexpectedly, Arnold notices bright flashing lights. He doesn't jump to conclusions about UFOs or UAPs; he looks for other aircrafts reported to be flying in the area, thinking that his plane might be dangerously close to another one. It isn't, and the closest reported plane is still miles away.
The lights continue. Arnold establishes he's not seeing reflections, but actual lights coming from flying objects near Mount Rainier. And the objects keep moving, and move closer to him, close enough that he can get a good look at them. They're not like any common human aircraft. They are shaped like discs or half-moons, they move at high speed, staying in a group all together, and they seem to have bright lights on them.
Arnold observes them for a while. He follows them, he tries to estimate their speed (which he calculates as being faster than any known human aircraft at the time), he then returns to his original destination and shares his story. Immediately, it's a media sensation.
It's possible that Arnold was a charlatan.
His story received immediate media sensation. Being a pilot, a logical, serious and in many ways average man, Arnold was seen as a more reliable witness than most. He was respected, and not immediately ridiculed or told he'd imagined everything. People were interested in the story. They believed it, even. It was no different than historical reports of "foo fighters", after all. No mention of aliens was made.
However, Arnold did ask the media for help uncovering this secret, and did receive from readers the theory that the UFOs might be extraterrestrial in nature. He didn't reject the theory: in fact, he seemed to warm up to it and make it his preferred theory. Again, he talked to the media about it.
Something clear in this story is that Arnold wasn't shy about talking to newspapers, and newspapers were keen on making the story into a sensation and Arnold into a celebrity. The more cynical side of us almost wants us to immediately jump to the conclusion that Arnold was making everything up in an attempt to gain celebrity. However Arnold wasn't the only one to withness the flying discs on Mount Rainier on the 24th of June, with a prospector on a nearby mountain as well as some people from nearby towns telling similar stories to their local newspapers.
The army claimed to know nothing. It seemed clear, then: either the government knew, and was hiding extremely high tech aircrafts from the public, presumably for military use (let's not forget, after all, these were the beginnings of the Cold War), or, and perhaps this possibility is worse, the government was as ignorant about the objects as the rest of us.
If the devices were of military use, we have received no proof of them being used in open, official military business. Despite these aircrafts being able to travel at a speed much higher than any other human aircraft, the military did not suddenly come out with extremely fast jets or rockets or planes. Neither did the Soviets, and after ruling out the American military and the Soviet military, there are not many other organisations to suspect. Perhaps, it's no wonder Arnold so easily settled on the hypothesis of aliens.
It is also a fact that after Arnold's sighting, thousand more were to come. It's not easy for a man of the 21st Century to read about a sighting made in 1948 and conclude whether it is credible or not. However, I believe I can state with very little doubt that many of these sightings were hoaxes. The risk many people incur in when trying to discuss ufology is to assume that the high number of false reports must prove that all reports are in a sense false. And those that aren't outright lies, people assume, must be a case of a misunderstanding, or of a person's mind playing tricks on them.
Personally, I believe we have to be careful and treat each and every sighting as a case in itself. It is to easy to dismiss theories that seem "wild" to us by accepting others that are plainly illogical, but closer to established reality we all know and accept as true.
Perhaps it is true that we are impressionable people who will think we see things that are not there after we saw them countless times in media, in sci-fi movies and comic books, and perhaps it is true that many of us are cunning people who will lie and cheat to get fame if that is what we desire. However, it is too dismissive to see a trend and expect it to be a rule. Regardless of whether these objects are alien in nature or not, we cannot simply accept as an explanation that we must have imagined them.
There have been sightings, of varying levels of credibility, involving actualy extraterrestrial life, too. We call these "close encounters of the third kind", and if a UFO witness gets some amount of respectability from the public, someone who claims to have seen an extraterrestrial being does not. But if we think about it, what reasons do we have to immediately assume we are the only intelligent beings in the universe?
When a skeptic (and I have to say, it is a great thing to be skeptical of all things) makes the point: "why assume that every UFO is connected to aliens?", they aren't wrong. But their skepticism stops there. It doesn't transfer to skepticism of the empty words of explanation public authorities give; it doesn't transfer to skepticism of all the "truths" that make us feel comfortable and safe. It isn't skepticism of anything that might bring the person insecurity. It is only skepticism of that which threatens the status quo, and which might bring instability, confusion and fear. But to simply be skeptical of something scary will not make it dissapear.
To answer the title's question, a UFO is nowhere close to being proof of alien activity. But a UFO raises questions we must ask, rather than dismiss. And we do have reports and sightings of creatures that seem extraterrestrial, and those reports should not be dismissed either.
Most of us have heard all about scandals the CIA reported themselves they had committed to: they experimented on the general population; they wilfully infected American citizens with illness; they attepted numerous assassinations all over the globe... the list goes on and on and on. Likewise, we are beyond the times in which believing the government is spying on us is a sign of being a lunatic conspiracy theory: it is simply common knowledge now. Should we then trust the government on the issue of what the UFOs they find are, and what the ones we see are?
I can imagine some of you will be thinking I am equating apples with oranges. But what I simply want you to do is to make up your own mind, without listening to either me or anyne else as your only source, on what this issue might be. When something sees unexplainable by common reasons, the uncommon reasons are the natural ones to turn to.