One definition of a tautology is the needless repetition of an idea, statement, or word. It strikes me that some of the "big questions" that are often discussed about the universe and life are little more than tautologies. They may be interesting to discuss, and if you believe in God or another cosmic consciousness or creator, they might even seem to have meaning. But based on what is actually observable, there is a big and complex physical universe that has been chugging along for billions of years, much longer than there have been human brains to do things like wonder why. And for a few thousand years, there have been human brains, some with enough security and free time to do the wondering. That's it!
The "anthropic principle" is the one that bugs me the most. This is the idea that since physical constants and conditions are suitable for stable matter, life, and intelligence, and since we can conceive of these things having been otherwise, someone or something must have set them that way so matter, life and intelligence can exist. But this is a tautology, since we wouldn't even be around if this were not true. If the conditions were wrong, or if there are multiple universes and some don't have these conditions, there would be no "we" around to wonder about this. It clearly assumes some purpose for the universe or a god or creator that could make decisions about this. And if that is the case, who or what created that creator, and in what universe, with what physical constants, defined by whom or what? It's an infinite regress.
Why not stick with what's observable? As far as I'm concerned, the universe simply is. That doesn't mean I can't be awed by its beauty or impressed with its intricacy, or that I can't be curious about its many parts and try to understand how some of them work (that's why I majored in physics). It just means I accept the universe as the natural state of things and that I don't believe it was created for the benefit of humans. We are simply one of the complex manifestations of its properties. Life with a cherry on top (more like cherry Jello).
There's a related question that is often asked about the universe: Why is there something rather than nothing? Again it's a tautology -- if there were nothing, nothing would exist to even think about this. There is no why there.
Sometimes people talk about "the will to live." I have often marveled myself at the enormous efforts that animals (including humans) will make to survive or even just carry on their normal life cycles. Things like certain migrating birds that fly thousands of miles twice a year to feed and reproduce. But the will to live is "baked into" life itself because natural selection eliminates those without it. So it's one of those things that is both amazing and commonplace, even inevitable. Of course it has some side-effects that we and some of our fellow creatures may perceive as happiness or contentment. When my dog and I are well-rested and well-fed and are enjoying the sights and smells of a walk on a sunny fall morning, that feeling came from evolution too. It's still pretty awesome.
And what about "are we alone in the universe?" This is a different kind of question, not a tautology. It's worth thinking about, and even doing some research, although it is not as exact question as some people may believe it to be. Clearly there is insufficient data now to evaluate this, though this may not always be so. Humans are certainly expending some effort to find information related to this question through space exploration and other means, and as we have identified thousands of exoplanets, we know at least that there are other places where life similar to ours could exist.
Many years ago, astronomer Frank Drake defined an equation that aims to estimate the number of intelligent civilizations in the universe. It identified some of the relevant parameters of this question, and defined them as probabilities, although some of them are not well enough defined to plausibly consider as a probability. Things like "the probability that an intelligent life form will develop a technological civilization." This is almost like asking "what is the probability that my karma is purple?" How to you define "karma?" Do karmas come in colors? How to you even define "intelligent life?" Does that mean "capable of developing technology?" Isn't that a tautology?
I just read an article describing a similar equation that considers the probability of detectable life. The "Seager Equation" is geared to our current knowledge of (many) exoplanets and how likely it is we could detect some planetary biosignatures. It is a bit more physical than Drake's equation, and does not consider intelligence or technology. A planet hosting only blue-green algae might have an oxygen-rich atmosphere detectable by spectroscopic methods if conditions like distance, star type, exoplanets in the habitable zone of the star, and others are right. The answer to this question? Her best estimate is 2. Not 42. Not millions. But not zero or .0005. That suggests it is worth looking.
I hope we are not alone in the universe. I hope there is simple life and intelligent life in abundance and that someday we can find it. But if we are alone, that's OK too. We will keep busy and maybe even survive to a ripe old age. We aren't here for any particular reason, but it's a great party, and I'm glad we crashed it.
-----
Nick Bostrom has a book on anthropic bias that apparently goes much more deeply into this subject. I haven't read it, but his web site has a lot of helpful information.
The picture here is by Slovak graphic designer Martin Vargic. It's a chart showing his artist's impressions of 500 of the some 2000 confirmed exoplanets arranged by mean temperature (x) vs. density (y). Although these planets have not been directly observed, the depictions are not completely fictional, as they are based on temperature, density, metal content, and other factors (the rings are purely for looks -- they are pretty common in our solar system, but only prominent on Saturn).
