"Birches" has been viewed as an important expression of Frost's philosophical outlook as well as a transitional poem that signaled a significant change in his literary development. Critic Jeffrey Hart, writing in Sewanee Review, terms "Birches" a "Frostian manifesto" due to the poem's skeptical tone regarding spiritual matters. Hart draws attention to the first part of the poem, where Frost presents the fantastic idea that the trees were bent by a boy, then discredits this thought with a more rational explanation regarding ice storms. In this manner, according to Hart, Frost casts doubt on the irrational aspects of the spiritual realm and upholds the value of earthly reality. "Birches," the critic writes, "asserts the claims of Frost's skepticism and sense of human limits against the desire for transcendence and the sense of mysterious possibility." A similar conclusion is reached by Floyd C. Watkins in an essay published in South Atlantic Quarterly. Watkins explains that Frost "contemplates a moment when the soul may be completely absorbed into a union with the divine. But he is earthbound, limited, afraid. No sooner does he wish to get away from earth than he thinks of 'fate'— rather than God. And what might be a mystical experience turns into fear of death, a fear that he would be snatched away 'not to return.'"

John C. Kemp, in his book Robert Frost and New England, notes that "Birches" was written at a time when Frost's work took a new direction. In 1913, the poet was completing work on North of Boston, a collection that is considered one of his finest. "Birches" was also composed in 1913 but was withheld from North of Boston. Kemp believes that Frost made this decision because he "evidently knew that he had done something different in ['Birches'], something not quite appropriate to the tone and dramatic impetus of the other poems" that were published in the volume. In specifying what that difference is, Kemp argues that the poems in North of Boston often reflect the observations of "perplexed and uncertain" outsiders as they observe rural New England life. "Birches" on the other hand, expresses the "confident, affirmative, and dominating" voice of the "Yankee farmer." The farmer is a self-assured native who delivers pronouncements and wisdom based on his experiences in the countryside. Frost's later poetry continued and intensified this attitude, according to Kemp, making "Birches" a precursor of Frost's subsequent work. The critic also contends that this change in direction ultimately harmed Frost's poetry. "By adopting the stance of the Yankee farmer," Kemp writes, "Frost committed himself to conventional poses and slighted his original, imaginative impulses."