The law tries to address this. If a defendant is aware that there is a significant risk of [X], but deliberately avoided information that might confirm [X], then knowledge that [X] can often be imported to them under the "willful blindness" doctrine. Though, as you can imagine, it can be difficult to apply this in practice since it is difficult to articulate the level of suspicion a defendant must have had in order to have been "willfully blind" rather than just ignorant.
https://scholarship.law.uci.edu/faculty_scholarship/803/
