The legal explanation for allowing two [differing] interpretations of the law, if reasonable, to stand is simply that courts must respect the legislator’s intention that such types of administrative decisions, which are protected by a privative clause, be not reviewed unless the tribunal has acted without or beyond its jurisdiction. This may sound strange to persons who are not familiar with judicial review and its subtleties, and I find it worthwhile to quote what late professor Chaïm Perelman (1912-1984) was writing in a text entitled “What the philosopher may learn from the study of law”, reproduced in annex to his work Justice, published in 1967 (Random House, New York) at page 94:
The diversity of laws is proof of our ignorance of true justice. That which conforms to reason cannot be just here and unjust there, just today and unjust tomorrow, just for one and unjust for another. That which is just in reason should, like that which is true, be so universally. Disagreement is a sign of imperfection, of a lack of rationality.If two interpretations of the same text are reasonably possible, it is because the law is ambiguous, therefore imperfect. If the law is clear, then at least one of the two interpreters disputes in bad faith. In any case, disagreement is a scandal, due either to the imperfection of the legislator or to the deceptive subtlety of the lawyers. The innate sense of justice, which each equitable judge certainly possesses, should permit the rapid reestablishment of correct order. That said, professor Perelman goes on at page 96 to provide a philosophical answer to such apparent injustice or human imperfection by telling this short anecdote:
The Jewish tradition, which never sought to conceive law on a scientific model, offers a significant story in this connection. In the Talmud two schools of biblical interpretation are in constant opposition, the school of Hillel and that of Shammai. Rabbi Abba relates that, bothered by these contradictory interpretations of the sacred texts, Rabbi Samuel addresses himself to heaven in order to know who speaks the truth. A voice from above answers him that these two theses both expressed the word of the Living God. The lesson of this story is clear: Two opposing interpretations can be equally respectable, and it is not necessary to condemn as unreasonable at least one of the interpreters.In fact, we admit that two reasonable and honest men can disagree on a determined question and thus judge differently. The situation is even considered so normal, both in legislative assemblies and in tribunals that have several judges, that decisions made unanimously are esteemed exceptional; and it is normal, moreover, to provide for procedures permitting the reaching of a decision even when opposing opinions persist.
As a supporter of deference and interpretive pluralism it is nice to see such weighty authority. From my lips to God's ears, I might even mutter...