The phrase "arguably it would have" is correct and usable in written English.
It can be used when presenting a point of view that suggests a certain outcome or interpretation could be valid or justifiable.
Example: "Arguably it would have been more effective to implement the changes sooner, given the circumstances."
Alternatives: "It could be said that it would have" or "One might argue that it would have".
But arguably, it would have the strongest impact on revitalizing and humanizing American politics.
Arguably, it would have been more difficult to land instruments on the moon prior to the detonation, which the 1959 paper recommended.
(You would not buy two because of the cost and you wouldn't wait around if you could refill your drink). Arguably it would have affected how school-age children purchase large-serve-sized sodas more than adults in New York City.
(In Australia's case the impact on saving is not clear cut: the saving rate has fallen nonetheless, though arguably by less than it would have done without the mandatory component).
It would be inaccurate to describe the Tour's three opening days on this side of the Channel as Prudhomme's specific brainchild but without the former journalist and TV commentator's approval – and his keen appreciation of what he feels having a race start in Great Britain means for the Tour de France – it is arguably much more unlikely it would have gone ahead.
It would have arguably been the greatest-ever world championship win … I think it could have been.
But arguably, if he'd succeeded, it would have strengthened his hand to make major departures from Blair policies in his early days.
It would have been anomalous, and arguably unconstitutional, for this jury to impose death when it refused to find Mr. Nichols guilty of murder.
Although other leading camera firms also came under extreme pressure at that time, had Kodak's management moved more quickly, it arguably would have bought itself valuable time to explore other options.
"Arguably this would have been exceeded if the country had not been 'closed due to snow' for two weeks in December," the SOLT said.
This problem could of course be alleviated somewhat if instead of merely appealing to modal structures as such, one could appeal to modal structures that arguably Aristotle would have thought are part of the very fabric of the world.
