A reader asks,
Would you explain the differences among compel, impel, and propel. Here is an instance that I read:“…I find myself returning again and again to the question of what compels us — what propels us — to record our impressions of the present moment in all their fragile subjectivity.”
The pel in compel, impel, and propel derives from the Latin verb pellere, “to drive,” as in the way one drives sheep, forcing them to go in a certain direction.
compel: transitive verb. To urge irresistibly, oblige, force. “The police compelled the motorist to stop.”
impel: transitive verb. To drive, force, or constrain a person to some action by acting upon her mind or feelings; to urge on, incite. In a literal sense, impel means to cause something to move onward. An engine, for example, impels a vehicle.
propel: transitive verb. To drive away or out. to drive or push forwards, onwards, or in a specified direction; to cause to move along. Figuratively, propel means “to encourage or promote an enterprise or activity.” One can “propel a person” in the sense of urging or spurring him on.
In the example provided by the reader–what compels us–what propels us–to record our impressions–, both compel and propel convey the idea of being driven to do something.
Compel conveys the idea that the person is being forced to do it; propel shows that the person is encouraged to do it by the same “what” that forces him to do it.
Three other pellere verbs in English are:
dispel: to drive asunder, scatter
expel: to drive out
repel: to push or thrust away