An argument based on likelihoods and probabilities is not anywhere close to rock solid proof, since the credibility of the folks determining those is what’s doubted in the first place.
Even if aliens with no human context at all showed up, a full proof will still convince them via pure logic and deduction from basic axioms.
An argument based on likelihoods and probabilities is not anywhere close to rock solid proof, since the credibility of the folks determining those is what’s doubted in the first place.