The number of possible motivations for extraterrestrials contacting humans seems endless, or at least bound only by our imagination. We have no actual knowledge of anything involving extraterrestrial intelligence, so any talk of motivation is merely speculation. That speculation has been the subject of a robust body of work in science fiction for decades.
Some of the possibilities include:
-They’re responding to our radio signals or messages placed on our spacecraft
-They just wanted to say hello
-They’re scientifically curious
-They want to convert us to their form of religion
-They want to warn us about something
-They want to reveal something
-They want to conquer us
-They want to be our friends
-They didn’t mean to make contact at all, it was a mistake
The science fiction writers have been much more creative than this meager list shows. My point is simply that the motivation of extraterrestrials should be of top concern to us in the event of First Contact. And that brings up another issue: will they tell us their true motivation for First Contact? It’s easy to assume that aliens would be honest. But honesty is a human trait and dishonesty perhaps just as common. It will be important for us to not only ask why they have made contact, but we will have to try and determine the underlying motivations that they might not be willing to share. This may sound a bit paranoid, but we would be dealing with creatures that we don’t understand at all. Caution and critical thinking would seem essential in such a situation.
Of course, motivation is a two-way street. The relationship will also be formed by our motivations for First Contact. It may seem like a cut and dried case of curiosity on our end. But is that the only motivation? First Contact would probably bring to light a bunch of things we would hope to gain in a new relationship: knowledge, new technology, a solution to global warming, revelations about the true nature of the physical world and new energy sources.