The principal ideological axis of Forest Gump is the opposition of the hero and his life-long love. Gump is a blessedly-innocent simpleton with a "heart of gold" who executes the orders of his superiors undisturbed by any ideological qualms or fanatical devotions. Renouncing even a minimum of "cognitive mapping"(Jameson), he is caught in a tautological symbolic machine towards which he lacks any ironic distance — a passive witness and/or participant of great historico-political battles whose significance he doesn't even try to understand (he never asks himself why he has to fight in Vietnam, why he is suddenly sent to China to play ping-pong, etc.).
His love is a girl fully engaged in the ideological struggles of the last decades (anti-Vietnam demonstrations, etc.) — in a word, she participates in history and endeavours to understand what is effectively going on. ... Gump, this slow-witted, automatic executor of orders, who doesn't even try to understand anything, gives body to the impossible pure subject of Ideology, to the ideal of a subject in whom Ideology would function flawlessly. The ideological mystification of the film resides in the fact that it presents Ideology at its purest as non-ideology, as extra-ideological good-natured participation in social life. That is to say, the ultimate lesson of the film is: do not try to understand, obey, and you shall succeed! (Gump ends up as a famous millionaire.) His girl, who endeavours to acquire a kind of "cognitive mapping" of the social situation, is symbolically punished for her thirst of knowledge: at the end of the film, she dies of AIDS. Forest Gump reveals the secret of ideology (the fact that its successful functioning involves the stupidity of its subjects) in such an open way that, in different historical circumstances, it would undoubtedly have subversive effects; today, however, in the era of cynicism, ideology can afford to reveal the secret of its functioning (its constitutive idiocy, which the traditional, pre-cynical ideology had to keep secret) without in the least affecting its efficiency.
Slavoj Zizek, The Indivisible Remainder: On Schelling and Related Matters