The phrase "arguably required" is correct and usable in written English.
It can be used when discussing something that can be claimed or asserted to be necessary, though there may be differing opinions on the matter.
Example: "In order to ensure the project's success, additional funding is arguably required to meet the necessary resources."
Alternatives: "possibly necessary" or "potentially essential".
QE was arguably required in 2009 to provide the banking sector with liquidity in the face of a frozen interbank lending market.
According to a filing to the judge from Mr. Feinberg last week, 155,000 people have filed in the various suits, but about 57,000 of those who have signed up for the lawsuit have not presented claims to the fund, a step arguably required under the Oil Pollution Act.
Information is arguably required by the public during any disaster, regardless of where that disaster occurs.
Confidentiality is arguably required by fair relations with government and businesses (Workplace Fairness, 2009, Other Internet Resources).
Enforcement mechanisms of a multilateral treaty are arguably required and these mechanisms may take on more strength if the growing knowledge of ecosystems services is employed to quantify an ecosystem capital framework.
The production of high quality effluent from membrane bioreactors (MBRs) arguably requires less supervision than conventional activated sludge (CAS) processes.
Batting arguably requires greater resources and intensity of coaching, I guess, which private schools offer more of, but it can't only be that.
Effective adaptation to unprecedented future conditions will arguably require innovation, the successful diffusion of new ideas and technologies into markets and practice.
Its European equivalent would, arguably, require a new treaty, just as the European Central Bank did, and all the political horse-trading that would entail.
The $2.6 trillion muni market is the last bastion of mom-and-pop investors, who arguably require tougher regulatory protection than the institutional investors that dominate the stock and corporate bond markets.
After a stint at Disney, where he proposed building a theme-park full of free-roaming robot dinosaurs, he turned his attention to building a mechanical clock that will run for 10,000 years, a task that arguably requires genius in its justification as well as its execution.
