How is violence a part of the theme in Fight Club by Chuck Palahniuk?

Violence is a significant part of the theme of masculinity that dominates Fight Club.

Violence can fit into several of the novel's themes. However, the novel's theme of asserting masculinity is directly linked to violence.  For the men who participate in fight club, violence is the path to reclaim their identity. When they fight, it is a rejection of the social expectation that has taken away from masculine identity. The perceived domestication of men is subverted through violence. Violence is the only way to undermine the inauthenticity of conventional society:  “...who you are at fight club was not who you are in the real world.”  Violence supplants the socially tranquil image of masculinity.  It tears this mask off and enables men to embrace a primally true nature. Violence in the form of hand to hand fighting, without weapons or even shirts, is a significant part of this reclamation.  

The novel's theme of reclaiming male identity suggests that violence can help to find truth.  Violence is a way for men to "lose everything" so that they can then gain "everything." Tyler suggests that he is "breaking attachment to physical power and possessions," and that violence is critical in this process because only through destruction of self is he able to "discover the greater power" of his spirit.  Such an idea reflects how violence is a significant part of the novel's theme of reclaiming male identity.