Why do people think there needs to be water and air on a planet for alien life?

and that, mon frere, is exactly my point.

Saying the Laws of Physics is universal is like an isolated tribe of Bojanglians deep in the forest saying "We speak Bojanglian, therefore the rest of the people on this planet must speak Bojanglian"

For all practical purpose, they are right (they have yet to come into contact with anything to contradict their beliefs) but from a technical standpoint theyre wrong (there are hundreds of languages).

I know, I know...an extreme example. But I like to keep my mind open, just in case. In the paraphrased words of tommy lee jones from MIB:

Hundreds of years ago, we knew the earth was flat. Yesterday, you knew we were alone in the universe. Imagine what you will know tomarow"

mrbojangles25

The thing is that we have observed stars and galaxies far, far away from where we live and have found them to obey precisely the same laws of physics as our own sun and galaxy. It's not just looking at our own planet and concluding things about the universe. Does this mean that it is theoretically impossible for there to be a theoretical galaxy that we haven't found that doesn't obey the laws of physics? No. But does that mean that we ought to hold that galaxy out as a very real possibility? No. It wouldn't make any sense to do so unless the evidence necessitated the establishment of such a galaxy in order to be free of contradictions.

Keeping an open mind is not the same as believing that anything could be equally likely to be the case. The whole purpose of science is narrowing down on what is most likely to be true and discarding for all practical purposes that which isn't, thus increasing the total amount of things we know about the universe. If scientists simply said "well we'll never know for sure, so we shouldn't bother", we wouldn't exactly have gotten very far.

The assumption that aliens can only live with air and water is far better than the assumption that they can grow on any rock, mainly due to the fact that there are three other large, air-less and water-less rocks in our solar system that don't have anything on them.

Except for the polar caps on Mars.

and that, mon frere, is exactly my point.

Saying the Laws of Physics is universal is like an isolated tribe of Bojanglians deep in the forest saying "We speak Bojanglian, therefore the rest of the people on this planet must speak Bojanglian"

For all practical purpose, they are right (they have yet to come into contact with anything to contradict their beliefs) but from a technical standpoint theyre wrong (there are hundreds of languages).

I know, I know...an extreme example. But I like to keep my mind open, just in case. In the paraphrased words of tommy lee jones from MIB:

Hundreds of years ago, we knew the earth was flat. Yesterday, you knew we were alone in the universe. Imagine what you will know tomarow"

mrbojangles25

Based solely on what we have seen? It sounds like you have impossibly high standards of verification.

Here's me:
*touches stove*
Ouch! Okay, I'm never doing that again.

Here's you:
*touches stove*
Ouch! I'm not going to draw any conclusions, though.
*touches stove in neighbor's kitchen*
Ouch! I'm not going to draw any conclusions, though.
*touches stove in grandma's kitchen*
Ouch! I'm not going to draw any conclusions, though.

Oleg_Huzwog

We've moved beyond the Bojanglians... Srsly.