The phrase "arguably since" is correct and usable in written English.
It can be used to introduce a statement that presents a point of view or opinion that is open to debate, often indicating a reason or justification for that opinion.
Example: "Arguably since the introduction of social media, communication has transformed dramatically."
Alternatives: "It can be argued that" or "One could contend that".
Arguably, since the writer finally turns against the taxidermist, the novel itself could be said to reject this approach.
If Scotland votes Yes to independence in next week's referendum it will be the most volcanic domestic political event since 1945 and arguably since well before that.
But Flavio Costa's team made it through, and got their act together in the Final Pool in a style which was unprecedented and arguably since unmatched.
Past and current administration officials say that Mr. Summers has been the Fed candidate-in-waiting arguably since Mr. Obama was first elected, notwithstanding that the president renominated Mr. Bernanke in 2009.
Well, a bit Grief, and its consequences ReprintsIn Britain, public sympathy for the military has not been this intense for many years, arguably since the Falklands conflict of 1982.
In the process his staff created one of the great political punch lines of the year – and arguably since the Clinton scandal – by reporting that he was hiking on the Appalachian Trail.
Arguably that has since been overtaken by the 2003 invasion of Iraq as the most unpopular conflict, though initially it was a military triumph.
Not since Jimmy Carter handed the office to Ronald Reagan — arguably not since Herbert Hoover yielded to Franklin Roosevelt — had a president of one party bequeathed a successor from another party so utter an economic disaster as George W. Bush bequeathed to Barack Obama.
A high-level campaign official called Mr. Biden's comments as bad a mistake as he has made in a long time — arguably since October 2008, when he "guaranteed" at a Seattle fund-raiser that Mr. Obama would face an international crisis within six months of taking office.
A rejiggered capital structure with less equity to debt is arguably adverse since it makes the risk of default greater given the stations' current performance.
Arguably not since the emergence of Nancy Friday has American letters produced a purveyor of erotica with such mass-market appeal.
