With re. the 'appeal to probability' and 'division' fallacies, while they may not allow one to be certain of the nature of an unknown entity, they do function well as a generic guide to what the nature of the unknown entity is most likely to be. Therefore, if you are unable to obtain the relevant observations directly (and/or if you are under time pressure) you can at least make a well-informed gamble (shortcut).
_________________ If you are doomed to be boring - make it short. Andre Geim