"Assuming, arguendo, that ..." and similar phrases are used in courtroom settings, academic legal settings, and occasionally in other domains, to designate provisional and unendorsed assumptions that will be made at the beginning of an argument in order to explore their implications.
The Latin word arguendō is the ablative case of the gerund of the verb arguere, which means 'assert' or 'clarify'.
[2] Assuming arguendo allows an attorney to examine the conclusions of premises without admitting that these premises—often the asserted facts of the opposing party—could be true.
Particularly in an appellate court, a judge may ask an attorney what the effects of a different set of assumptions, made arguendo, about the facts governing a situation might be.
Asking these questions is especially useful in exploring whether different fact patterns might limit the proper scope of a possible holding in a given case.