In Dubious Battle surprisingly garnered very favorable views upon its publication in 1936, despite its controversial subject matter. The Washington Post dubbed it "primarily a work of fine craftsmanship and secondly a strong proletarian outcry" ("Recommended" B8). One of the earliest reviews by Fred T. Marsh of the New York Times proclaimed In Dubious Battle to be "one of the most courageous and desperately honest books that has appeared in a long time. It is also, both dramatically and realistically, the best strike and labor novel to come out of our contemporary economic and social unrest" (BR7). Though both Marsh and Steinbeck himself predicted fans, especially those who enjoyed the light-hearted nature if his previous work Tortilla Flat (1935), might be off put by the novel's grim tone, In Dubious Battle ended up being a commercial success and topped many bestseller lists at the time.
Most of the negative criticism of In Dubious Battle came from detractors with leftist sympathies who believed Steinbeck failed to realistically portray the true motives and spirit of labor organizers. Writer Mary McCarthy denounced In Dubious Battle for what she saw as ineffective philosophical generalizations, which overshadowed the "legitimately dramatic incidents of the strike" (qtd. in Benson 324). Although Steinbeck had gone to great lengths to research party organizers and contemporary strikes to authentically portray the novel's action, the party organizers after whom Steinbeck modeled his characters also questioned Steinbeck's representation of their motives. According to biographer Jackson Benson, Pat Chambers and Caroline Decker, prominent labor organizers at the time, who are popularly believed to be the models for Mac and Jim, objected to "the emphasis on the calculated manipulation of the strikers as a mob, rather than an emphasis on the actual spirit of brotherhood and mutual support that made the strike possible and produced eventual success" (304).
Steinbeck also drew criticism for the violence portrayed in In Dubious Battle, most notably from critic Maxwell Geismar, who believed the use of violence and brutality in the novel was more for effect than for insight (Perez 48). Others seemed to disagree, however, recognizing Steinbeck purposefully gave the novel a dark and violent tone to realistically portray labor disputes. Accounts of clashes, such as the infamous incident in San Francisco known as Bloody Thursday in 1934, suggests that Steinbeck's portrayal of the violence surrounding labor disputes is not at all exaggerated.
In response to both the positive and negative criticism of the novel's realism, Steinbeck admitted he was more interested in the philosophical underpinnings of the work than the action and did not intend for In Dubious Battle to be a propagandist piece for Communists. In a letter to friend George Albee he explains:
I don't know how much I have got over, but I have used a small strike in an orchard valley as the symbol of man's eternal, bitter warfare with himself. I'm not interested in strike as a means of raising men's wages, and I'm not interested in ranting about justice or oppression, mere outcroppings which indicate the condition. But man hates something in himself. [. . .] And this self-hate which goes so closely with self-love is what I wrote about. (qtd. in Benson 304)
Discovering from where that self-hate emanates and examining the ever-widening scope of its destructive power becomes a central focus of Steinbeck's career as he will go on to repeatedly examine how humans attempt to reconcile their self-destructive tendencies with their tendency for great compassion and love from a multitude of perspectives.
Overall, In Dubious Battle is considered to be one of Steinbeck's best novels, though it has been overshadowed by The Grapes of Wrath. Although In Dubious Battle tackles similar themes and situations as The Grapes of Wrath, it received notably less critical acclaim, even though it too is sympathetic towards the plight of migrant workers. While his depiction of the labor organizers' motives have been questioned, the compelling, realistic action of the storyline has been nearly universally praised attesting to Steinbeck's mastery of artful storytelling very early on in his career.