Dagny Taggart

Dagny Taggart is the protagonist of Atlas Shrugged: Vice-President in Charge of Operation of Taggart Transcontinental, and the person who actually runs the railroad her brother nominally presides over. She is the character through whom the reader discovers the strike, and the last of the novel's producers to accept that the right response to the looters' world is to leave it.

“I started my life with a single absolute: that the world was mine to shape in the image of my highest values and never to be given up to a lesser standard, no matter how long or hard the struggle.”
~ Dagny Taggart, Atlas Shrugged

Her function in the novel

Dagny is the reader's surrogate. She has the strikers' virtues in full — independent judgment, unbreached competence, an unembarrassed love of her own work — and none of their knowledge, so the mystery unfolds at her pace. Every clue the reader gets, she gets; every wrong hypothesis the reader forms, she forms first.

Her professional arc is the construction of the John Galt Line, built with Rearden Metal against the unanimous opinion of the press, the scientific establishment and her own board. The line succeeds, and its success is what makes it a target. That sequence is the novel's compressed statement of its economics: achievement is punished not in spite of being achievement but because of it.

Why she is the last to strike

The novel's central difficulty for Dagny is that her virtue is what holds her in place.

She loves the railroad, and the railroad is a physical thing she can keep running by working harder. Every man who vanishes makes her more necessary, and being necessary is exactly what she has always wanted. John Galt identifies her as the hardest of the strikers to win precisely because the trap is baited with her own values rather than against them, and because she reads the strike as desertion — a betrayal of the thing that deserves loyalty.

The novel gives that reading its due before overturning it. The strikers are not withholding a favour; they are declining to be the means by which the system survives its own premises. Dagny is presented, in the strikers' own term, as the scab, and the argument is made to her at length rather than assumed. Her final change of mind comes only when continuing means putting Galt himself into the looters' hands. See Sacrifice and Trader Principle.

Galt's Gulch

Dagny crashes her plane pursuing what she takes to be the destroyer and lands in the strikers' valley, where she meets the men who vanished and finds them working. Rand uses the episode to show the alternative concretely rather than to argue it: the Gulch is a functioning society of traders in which nothing is given and nothing is taken.

Dagny then chooses to return to the outside world, which is not a failure of understanding but the last stage of it — she has to exhaust the possibility of saving the railroad before she can act on the conclusion that it cannot be saved on these terms.

The three men

Dagny's relationships with Francisco d'Anconia, Hank Rearden and John Galt are, on Rand's account of sex, a sequence rather than a series of substitutions. Each is the highest value she has yet encountered, and each relationship ends when she encounters a higher one — not by comparison of qualities but because her own understanding has advanced.

Rand treated romantic response as an expression of a person's fundamental values, so the progression tracks Dagny's growing grasp of what she is looking at. Nothing in the sequence is presented as a betrayal, and each man understands the terms. See Reason-Emotion Dichotomy and Value.

Common misunderstandings

That she is a female lead in a token sense. She is the novel's viewpoint character and its most active agent. Rand's stated ideal-man figure is Galt; Dagny is the one whose choices drive the plot.
That she is inconsistent for resisting the strike so long. Rand constructed the resistance deliberately. A character who accepted the argument on first hearing would have made the argument unnecessary to state.
That the novel treats her love of the railroad as a flaw. It treats it as the virtue that has been turned against her. What she has to identify is not that she cared too much but what her caring was being used for.
That her relationships illustrate a doctrine of trading up in partners. The claim is about the relation between values and desire, not a ranking procedure. See Sex.

Discussion

References

Rand, Ayn. Atlas Shrugged. Random House, 1957.
Rand, Ayn. "The Goal of My Writing", The Romantic Manifesto. World Publishing, 1969.
Peikoff, Leonard. Objectivism: The Philosophy of Ayn Rand, chapter 9.