That's right! So how would you define life? Or the meta-question, why bother? We gain nothing from figuring out what's "alive" and what has "merely" a rich complexity.
"Search for life" is a category error.
> The thing about searching for "life" over "intelligence" is that life doesn't necessarily need to be intelligent for it to be interesting.
If something is interesting, why do we care if it's "life?"
Anything we find is likely to operate on some scale vastly different than what we're familiar with. We won't even agree on whether it's alive.
> Whereas when you're visiting a planet, you can observe a wider scope of life as it need not be intelligent (as we can perceive anyway) for markers to be identified.
My hope is we'll find markers that are clearly weird and that aren't evidence of life but maybe something more and weirder that we don't understand.
Isn't that even more interesting? Why hope to find life, when we know life is already possible?
> "Search for life" is a category error.
To be honest I think you're over thinking the whole "life" thing. It's just a label. You could replace that term and still have the same arguments. eg "What would someone define as 'interesting'? What does that category even mean?". Or "complex", or "intelligent" or any other label.
> Why hope to find life, when we know life is already possible?
Possible, yeah. But it's unique in that we are constantly finding a multitude of other phenomena in the universe yet we've only ever observed life on our own planet. That alone makes this topic interesting in my opinion.
I don't see why it has to be an either / or though. Nobody is suggesting we search for life at the sacrifice of learning more about black holes...or whatever.
This is not to subtract from geology which is an interesting and useful study, just to say it is unlikely we would discover anything very new if we could somehow examine every planet in the universe. However if we add in life we would expect a lot of interesting variety to study.
We know it's possible, but we've also seen it happen only once. The observational data we have suggests the universe is mostly dead - that is, not complex. Or, in other words, boring. Discovery of any complex process on a comparable level to even simplest of what we call life would be a civilization-changing breakthrough. It would prove the universe is not boring.
(It would also ultimately kill off most of our existing religions.)
Religion tends to be very careful to stay in the area of not providing a testable hypothesis which means that new alien knowledge won't prove it wrong.
> Religion tends to be very careful to stay in the area of not providing a testable hypothesis which means that new alien knowledge won't prove it wrong.
That's true, but until very recently, the idea of life elsewhere wasn't really considered seriously.
Source: I'm not religious but I've been dragged to plenty of sermons by the extended family.
I think you may be underestimating the tenacity of religions
Unconditional belief in the unknowable gives you an awful lot of wiggle room when it comes to evidence.
The thing about searching for "life" over "intelligence" is that life doesn't necessarily need to be intelligent for it to be interesting.
I also think the SETI example you've made is a tad unfair because their process dictates that their search be for intelligence (crudely put, radio transmissions). Whereas when you're visiting a planet, you can observe a wider scope of life as it need not be intelligent (as we can perceive anyway) for markers to be identified.