Notice the major points in Lehi’s argument as to why there must be opposition before a man can be truly free and before he can experience real joy: (1) Every law has both a punishment and a blessing attached to it. (2) Disobedience to law requires a punishment which results in misery. (3) Obedience to law provides a blessing which results in happiness (joy). (4) Without law there can be neither punishment nor blessing, neither misery nor happiness—only innocence. (5) Thus happiness (or joy) can exist only where the possibility of the opposite (unhappiness or misery) also exists. (6) In order to exercise free agency a person must have the possibility (and the freedom) of choice; in a world without law—and thus without choice—there could be no freedom of choice and thus no true exercise of free agency. (2 Nephi 2:15-16; see also Alma 12:31-32 and Alma 42:17-25.)
Lehi does not say it is necessary to choose evil in order to recognize good from evil, but he does make it quite clear that a choice of opposites is necessary for growth.
The major points in Lehi’s explanation of the necessity of opposition might be diagramed as follows:
law
obedience (righteousness) disobedience (wickedness)
blessing punishment
happiness (joy) unhappiness (misery)
The teachings of Lehi are consistent with statements of the Lord in the Doctrine and Covenants:
There is a law, irrevocably decreed in heaven before the foundations of this world, upon which all blessings are predicated—And when we obtain any blessing from God, it is by obedience to that law upon which it is predicated. (D&C 130:20-21.)
For all who will have a blessing at my hands shall abide the law which was appointed for that blessing, and the conditions thereof, as were instituted from before the foundation of the world. (D&C 132:5.)