In less descriptive terms, the expression “there’s no use beating / flogging a dead horse” essentially means to “bring up an issue that has already been concluded is futile.” A necessary point to convey, but the imagery of this well-known idiom is enough to make my tummy turn. English politician and orator John Bright seems to have been very fond of the phrase and may even have originated it. In 1872, The Globe newspaper quotes a speech Bright gave to Parliament in which he said that rousing the government from its apathy on a particular issue (The Reform Act of 1867, if you want to know) would be “like trying to flog a dead horse to make it pull a load.” There is evidence, however, that he said it even earlier than that, as it is attributed to him as early as 1859.
Either way, I think 150 years is long enough for this violent expression to have had its time in the sun. But that’s the amazing thing about language: it’s fluid, it’s unpredictable, and it’s fickle. But it’s also stubborn; steadfast, and obstinate. If you tell it to change, it will dig its heels in and resist even more. However, language’s only power lies in usage. Like the annoying tease who stops teasing when you ignore him, so, too, can offensive or distasteful expressions wither and die from underuse. We are the carriers of such expressions, and with conscious neglect, we can strip them of their power.
And so, I give you an alternative: “There’s no use watering a dead flower.” Visual. Evocative. To the point. Try it on. Say it aloud. Practice it at home and in public. Share it with loved ones. Write it into a speech — to Parliament or otherwise. With constant use, it can grow and flourish and leave the violent version in the dust.