Experts agree legal writers should avoid the and/or construction, but a controversy has arisen over whether using it is merely ill advised or worse, "just plain dumb." The underlying issue concerns the meaning of the disjunctive-conjunction or, and two theories contend. While or's semantic sensitivity to context is unmistakable, some disputants maintain that or's default meaning, its meaning when context is neutral, is inclusive, so a or b is true is itself true if a is true, b, is true, or both are true. In contrast, the simultaneous truth of a and b in an exclusive disjunction falsifies it if a or b is true. If or is an inclusive disjunction, then the and/or construction is "just plain dumb": the unenhanced or already means and/or. Allowing for exceptions, linguist Geoffrey Pullum explains the and/or construction uses overstatement to exaggerate the inclusiveness ordinary or already possesses, but in legal writing, using hyperbole is perhaps just another route to being "just plain dumb."
Pullum argues by appeal to compelling examples; his most persuasive example is:
Is Gordon Brown or the Pope in the U.S. today?Knowing that the Pope is in the country, one answers "yes," without worrying that Gordon Brown is visiting. The visitors' arbitrary identities seem to preclude contextual influence, allowing or's default meaning to emerge, but context is only weak, not completely absent. Despite the unrelatedness of the two actors, the question's implied or habitual context involves summoning one of the actors, and it's harder to imagine a situation where you would need to know that either Gordon Brown or the Pope but not both is in the U.S.
If the Gordon Brown example offers Pullum some comfort, contrary examples abound. Here's one from the label on a tomatoes' package supporting the Pullum-rejected exclusive account of or:
To maintain freshness coated with vegetable, petroleum, beeswax and/or shellac-based wax or resin.The label includes both or and and/or because "beeswax or shellac-based wax or resin" reads exclusively. Without the inclusive construction and/or, the label would be inaccurate if the tomatoes' coating contained both ingredients: beeswax and shellac-based wax; or beeswax and resin.
This example, admittedly, doesn't conclusively show or is exclusive, as context might yet intrude; the predominance of subtle contextual influences brings default meaning itself into question. Rejecting default meaning altogether still rebuts and/or's inherent stupidity: and/or avoids being "just plain dumb" whenever the construction avoids redundancy. The examples don't settle or's meaning, but they rebut a strong inclusive default meaning as Pullum proposes, in which context effects are due only to logic, not to habit.
Three facts of usage and native-speaker's intuition demonstrate a (weak) presumption favoring an exclusive-disjunction interpretation for or: 1) English dictionaries universally define or as exclusive by describing its conjuncts as "alternatives"; 2) while and/or is indisputably an inclusive disjunction, English has no artificial exclusive disjunctions, as we might expect as compensation if or, unenhanced, were inclusive; and 3) as in elementary mathematical-logic classes, where the teacher must emphasize or's subject-specific inclusive meaning to dissuade students from importing its natural exclusive meaning, speakers' intuitions lead them to interpret or as exclusive.
Judicious use of and/or isn't stupid and results in no worse than an uneuphonious and slightly confusing product, each because the construction has no counterpart in ordinary speech, but writers of and/or seldom use it judiciously. The next entry will discuss the main source of and/or excess, the writing defect weaseling.