Aliens probably just want to eat our brains and gain our intelligence. This is why we should never trust other species and kill them at first sight. I love my family and i don't want aliens to come to earth. Praise the good Lord and stay on your own planet.
If we fight them they may fight back and they may have some extremely sophisticated technology that could destroy or enslave us. If aliens contact us we should try to make friends. Maybe they can help us. They may be able to help us do things like use wormholes to travel between stars or give us the cure for cancer.
Think about Star Trek. If Cochrane had shot the Vulcans at first sight, like in the alternate universe in DS9, the humans would have become near slaves to the other species. But when he worked together with the aliens, all of human suffering, poverty, and wars disappeared within a few years. It also brought in an age of cooperation, peace, and exploration.
No, we should not fight aliens at first sight, because the aliens might be friendly. The aliens could be waiting to meet us. If we might them at first, if they are more sophisticated than us, they might come to earth and destroy all of us, or takes us as their slaves.
If they can track life down and travel thousands of LIGHT YEARS in space so Fast then the chances are that they're trillion times more advanced than us !
If we show any signs of deliberate hostility despite having intelligence we'd be in GRAVE danger,the only possible thing we should do is appreciate their efforts and welcome them in a peaceful gesture and maybe give them some beer and chips.
We should absolutely not seek to fight aliens at first sight. Unless they are threatening our safety, why would we not seek peaceful relations with them in the hopes of befriending them. We could gain invaluable knowledge were we to focus on understanding their existences rather than ignorantly attacking them.
If we come into contact with aliens on our own planet we almost certainly need to seek peace as a first strategy. Stephen Hawking made an excellent point when he observed that if aliens have the technology to travel here, and we do not even have the technology to find them, chances say that the ensuing incident would look similar to the Native American and Europeans after the discovery of the Americas.
If we are immediately attacked, we have little choice, but peace should definitely be investigated and attempted.
Contact with an extraterrestrial species could improve our own life on earth. If we attacked the species at first sight, without provocation, and without knowing if the species is peaceful, we would forever damage our reputation for peaceful encounters. If there is a possibility to learn and advance or civilization from information we could obtain from an alien race, we should definitely not attack them before finding this out.
Who is to say the "aliens" are bad? To them, we are the aliens. Should they want to fight us? They are curious and if they are real, why not try and be friendly? We listen to all this horror stories, but what is the truth? We can't understand them and they look different so immideately they are bad.