A terrible scroll of Hell is shown depicting the fall of the castle. There are no real sounds as the scroll unfolds like a daytime nightmare. It is a scene of human evildoing, the way of the demonic Ashura, as seen by a Buddha in tears. The music superimposed on these pictures is, like the Buddha's heart, measured in beats of profound anguish, the chanting of a melody full of sorrow that begins like sobbing and rises gradually as it is repeated, like karmic cycles, then finally sounds like the wailing of countless Buddhas.—Ran Screenplay
One central theme in the film is chaos; in many scenes Kurosawa foreshadows it by filming approaching cumulonimbus clouds, which finally break into a raging storm during the castle massacre. Hidetora is an autocrat whose powerful presence keeps the countryside unified and at peace. His abdication frees up other characters, such as Jiro and Lady Kaede, to pursue their own agendas, which they do with absolute ruthlessness. While the title is almost certainly an allusion to Hidetora's decision to abdicate (and the resulting mayhem that follows), there are other examples of the disorder of life, what Michael Sragow calls a "trickle-down theory of anarchy." Kurogane's assassination of Taro ultimately elevates Lady Kaede to power and turns Jiro into an unwilling pawn in her schemes. Saburo's decision to rescue Hidetora ultimately draws in two rival warlords and leads to an unwanted battle between Jiro and Saburo, culminating in the destruction of the Ichimonji clan.
The ultimate example of chaos is the absence of gods. When Hidetora sees Lady Sué, a devout Buddhist and the most religious character in the film, he tells her, "Buddha is gone from this miserable world." Sué, despite her belief in love and forgiveness, eventually has her head cut off. When Kyoami claims that the gods either do not exist or are the cause of human suffering, Tango responds, "[The gods] can't save us from ourselves." Kurosawa has repeated the point, saying "humanity must face life without relying on God or Buddha." The last shot of the film shows Tsurumaru standing on top of the ruins of his family castle. Unable to see, he stumbles towards the edge until he almost falls over. He drops the scroll of the Buddha his sister had given him and just stands there, "a blind man at the edge of a precipice, bereft of his god, in a darkening world." This may symbolize the modern concept of the death of God, as Kurosawa also claimed "Man is perfectly alone... [Tsurumaru] represents modern humanity."
What I was trying to get at in Ran, and this was there from the script stage, was that the gods or God or whoever it is observing human events is feeling sadness about how human beings destroy each other, and powerlessness to affect human beings' behavior.—Akira Kurosawa
In addition to its chaotic elements, Ran also contains a strong element of nihilism, which is present from the opening sequence, where Hidetora mercilessly hunts down a boar only to refrain from eating it, to the last scene with Tsurumaru. Roger Ebert describes Ran as "a 20th-century film set in medieval times, in which an old man can arrive at the end of his life having won all his battles, and foolishly think he still has the power to settle things for a new generation. But life hurries ahead without any respect for historical continuity; his children have their own lusts and furies. His will is irrelevant, and they will divide his spoils like dogs tearing at a carcass."
This marked a radical departure from Kurosawa's earlier films, many of which balanced pessimism with hopefulness. Only Throne of Blood, an adaptation of Shakespeare's Macbeth, had as bleak an outlook. Even Kagemusha, though it chronicled the fall of the Takeda clan and their disastrous defeat at the Battle of Nagashino, had ended on a note of regret rather than despair. By contrast, the world of Ran is a Hobbesian world, where life is an endless cycle of suffering and everybody is a villain or a victim, and in many cases both. Heroes like Saburo may do the right thing, but in the end they are doomed as well. Unlike other Kurosawa heroes, like Kikuchiyo in Seven Samurai or Watanabe from Ikiru, who die performing great acts, Saburo dies pointlessly. Gentle characters like Lady Sué are doomed to fall victim to the evil and violence around them, and conniving characters like Jiro or Lady Kaede are never given a chance to atone and are predestined to a life of wickedness culminating in violent death.
All the technological progress of these last years has only taught human beings how to kill more of each other faster. It's very difficult for me to retain a sanguine outlook on life under such circumstances.—Akira Kurosawa
According to Michael Wilmington, Kurosawa told him that much of the film was a metaphor for nuclear warfare and the anxiety of the post-Hiroshima age. He believed that, despite all of the technological progress of the 20th century, all people had learned was how to kill each other more efficiently. In Ran, the vehicle for apocalyptic destruction is the arquebus, an early firearm that was introduced to Japan in the 16th century. Arquebuses revolutionized samurai warfare, and the age of swords and single-combat warriors fell rapidly by the wayside. Now, samurai warfare would be characterized by massive faceless armies engaging each other at a distance. Kurosawa had already dealt with this theme in his previous film Kagemusha, in which the Takeda cavalry is destroyed by the arquebuses of the Oda and Tokugawa clans.
In Ran, the battle of Hachiman Field is a perfect illustration of this new kind of warfare. Saburo's arquebusiers annihilate Jiro's cavalry and drive off his infantry by engaging them from the woods, where the cavalry are unable to venture. Similarly, Saburo's assassination by a sniper also shows how individual heroes can be easily disposed of on a modern battlefield. Kurosawa also illustrates this new warfare with his camera. Instead of focusing on the warring armies, he frequently sets the focal plane beyond the action, so that in the film they appear as abstract entities.