What have we stopped noticing?
The things we say, do, and accept without thinking twice.
Look closer where it comes from, what it assumes, and the case for keeping it
What you mean by it
To keep arguing a point that's already settled.
What it's actually picturing
Read literally, someone is whipping a horse that can no longer respond. It's been in print since 1859. Older “dead horse” sayings were about work that had already been paid for.
What it takes for granted
Hitting a living horse is the unstated norm the joke depends on.
Worth knowing
Usually said with a wince and a smile. Few people picture it; most people wince when they do.
The case for keeping it
The phrase is itself a criticism of futile cruelty. It is hardly an endorsement.
Say it plainly
Go over old groundBelabor the point
Or have some fun
Feed a fed horse
Where this comes from
- Flog a dead horse · The Phrase Finder