|Which is correct?
The CSO explained that you ___________ the desire of employees to be helpful to their bosses, which explains why they so often respond to social engineering tactics in email pretending to be messages from head office.
a. can’t underestimate
b. shouldn’t underestimate
c. can’t overestimate
Answer: b or (less probably) c
Although can’t underestimate and shouldn’t underestimate might seem to have similar meanings, in fact they’re quite distinct:
If you can’t underestimate something, it’s so small that no matter how tiny you estimate it to be, it’s smaller than that.
So, in this case, if you can’t underestimate employees’ desire to be helpful to their bosses, that means that they hardly want to be helpful to their bosses at all. Which could, of course, be the case — but is not usually the meaning intended in this kind of sentence.
If you can’t overestimate something, it means that no matter how great you estimate it to be, your estimate will fall short of the reality. In this case, it would mean that employees want to be helpful to their bosses beyond anything you could possibly imagine. Which doesn’t seem quiiiiite correct either.
What we want here is shouldn’t underestimate, because the considerable (although not unimaginable) desire of employees to help their bosses can lead to a real security threat.