Usage of "lest"
Is the following sentence with "lest" grammatical?
"You shouldn't swear lest you'll look like a hypocrite."
Lest is generally followed by a verb clause, and the construction as a whole creates a subjunctive mood (A hypothetical).
No auxiliary verbs like "will", "would" etc are used following "lest", although "should" can be used in many cases.
The grammatical version, in this case, is either
- You shouldn't swear lest you look like a hypocrite
- You shouldn't swear lest you should look like a hypocrite
[Props to Edwin for reminding me of the grammaticality of "Should"]