Comment by mrob

It's not a question of probabilities. You're advocating punishing people for wrongdoing you anticipate them doing in the future. This is the argument behind racial profiling, and it's widely considered immoral. Would you mark a black student down because they're statistically more likely to fail in the future? If you suspect a student lacks understanding then you should actually test that understanding, not just assume they're going to fail and punish them preemptively.