It depends on what your criteria for ‘truth’ are, which I think is exactly what we’ve been debating here. What degree of uncertainty are you comfortable with? To call a statement ‘true’ does it have to be testable? Repeatable? Is a strong argument good enough?

I think a great deal of philosophy tends to allow for more leeway here than standard scientific practice, and you seem to have stricter criteria than the average philosopher. Personally I think propositions arrived at via the scientific method are probably the ideal form for truth but that for certain questions this isn’t always a possible method of investigation—or not possible at this moment in history. To me, that doesn’t make the ‘speculative’ answers any less interesting or valuable, at least as possibilities, but yeah they could be wrong