If you aren’t sure about something, you can’t just throw up your hands, say “well, we can’t be sure”, and then behave as if the answer you like best is true.
We have math for calculating these things, based on the probability different options are true.
For example, we don’t know for sure how abiogenesis works, as you correctly note. Thus, we can’t be sure how rare it ought to be on Earthlike planets—it might require a truly staggering coincidence, and we would never know for anthropic reasons.
But, in fact, we can reason about this uncertainty—we can’t get rid of it, but we can quantify it to a degree. We know how soon life appeared after conditions became suitable. So we can consider what kind of frequency that would imply for abiogenesis given Earthlike conditions and anthropic effects.
This doesn’t give us any new information—we still don’t know how abiogenesis works—but it does give us a rough idea of how likely it is to be nigh-impossible, or near-certain.
Similarly, we can take the evidence we do have about the likelihood of Earthlike planets forming, the number of nearby stars they might form around, the likely instrumental goals most intelligent minds will have, the tools they will probably have available to them … and so on.
We can’t be sure about any of these things—no, not even the number of stars! - but we do have some evidence. We can calculate how likely that evidence would be to show up given the different possibilities. And so, putting it all together, we can put ballpark numbers to the odds of these events—“there is a X% chance that we should have been contacted”, given the evidence we have now.
And then—making sure to update on all the evidence available, and recalculate as new evidence is found—we can work out the implications.
If you aren’t sure about something, you can’t just throw up your hands, say “well, we can’t be sure”, and then behave as if the answer you like best is true.
We have math for calculating these things, based on the probability different options are true.
For example, we don’t know for sure how abiogenesis works, as you correctly note. Thus, we can’t be sure how rare it ought to be on Earthlike planets—it might require a truly staggering coincidence, and we would never know for anthropic reasons.
But, in fact, we can reason about this uncertainty—we can’t get rid of it, but we can quantify it to a degree. We know how soon life appeared after conditions became suitable. So we can consider what kind of frequency that would imply for abiogenesis given Earthlike conditions and anthropic effects.
This doesn’t give us any new information—we still don’t know how abiogenesis works—but it does give us a rough idea of how likely it is to be nigh-impossible, or near-certain.
Similarly, we can take the evidence we do have about the likelihood of Earthlike planets forming, the number of nearby stars they might form around, the likely instrumental goals most intelligent minds will have, the tools they will probably have available to them … and so on.
We can’t be sure about any of these things—no, not even the number of stars! - but we do have some evidence. We can calculate how likely that evidence would be to show up given the different possibilities. And so, putting it all together, we can put ballpark numbers to the odds of these events—“there is a X% chance that we should have been contacted”, given the evidence we have now.
And then—making sure to update on all the evidence available, and recalculate as new evidence is found—we can work out the implications.