A COMMON pitfall in writing is to mistake possibility or simple probability for certainty. Either from faulty grammar or faulty thinking, writers can make sweeping or hasty generalizations — statements that assert too much on too little evidence. They overstate their case and undermine the very argument they are making.

Consider this opening statement of a recent advice column: 'Your greatest weakness is the one that you are unaware of. Because you do not know that it exists, you become vulnerable to the one who spots it.' By using the superlative 'greatest' without qualification, this statement makes an assertion that can't be possibly proven. Being unaware of a weakness doesn't necessarily make it one's greatest weakness; more likely, one's greatest weakness would be the weakness one actually suffers from and is fully aware of. The premise thus proves logically indefensible.