Do you think that socialism or social equality is a dominant theme in the play, Arms and the Man? Give a reasoned answer.

Socialism and social equality are predominant themes in Arms and the Man. During the time Shaw wrote the play, Britain saw the emergence of a number of class struggles. In fact, Shaw was a supporter of these movements and became a full-time advocate of socialism. In the play as well, there are several subtle yet powerful dialogues that highlight Shaw's view on class distinctions. Captain Bluntschli, it appears, functions as Shaw's mouthpiece and makes his political and social beliefs clear to the audience.
The Petkoffs serve as symbols of aristocracy and talk down to their servants. They ignore no opportunity to show off their wealth and status. The servants, Nikola and Louka, represent two extreme positions of the working class, subservience and defiance. Bluntschli, a pragmatic bourgeois captain, serves as the voice of the emerging middle class. In the exchange of dialogue between all these characters, Shaw seems to suggest that division between the classes is arbitrary and that there are no real class distinctions beyond the way people of each class are treated by society.

Shaw's play emphasizes social equality rather than socialism. Socialism is an economic system that Shaw supported that puts ownership of banks and industry in the hands of the government. Arms and the Man does not focus on changing the economic system.
Instead, it is a social satire with an emphasis on attacking the class structure. In a light-hearted way, it argues that the class system creates illusions of romantic love and heroism that cause real damage. Sergius and Raina don't really love each other, for example, but feel compelled to play out a false scenario in which she falls in "love" with a conventional military "hero," and he with an upper-class young woman. In reality, Sergius is no hero, but a blundering fool who only wins a battle because the other side is evenly more grossly incompetent than he is. In reality, too, Sergius prefers Raina's maid to her and carries on with the maid throughout the play.
A better hero for the modern world, the play argues, is the hard-headed but kind-hearted Bluntschli, who perceives life as it really is and doesn't try to live by false aristocratic ideals. 

Socialism and social equality were both important themes in the work of George Bernard Shaw, and he wrote many essays and prefaces advocating both of these causes. In the play Arms and the Man, we see one of Shaw's commonly repeated points, that aristocratic ideals, especially as expressed in heroic poetry and similar artistic genres, harm people both as individuals and as couples. 
Both Sergius and Raina are unhappy with the constraints of an aristocratic ideology that not only limits their personal development but also seems to be inexorably constraining them to an unhappy marriage. The voice of reason and the character we are intended to admire most is Captain Bluntschli, a Swiss bourgeois, who lacks the false ideology of the Bulgarian aristocrats and combines a simple and pragmatic approach to war with a rather charmingly romantic approach to marriage, focused not on heroic ideals but on personal emotions.