Freedom
Sartre was obsessed with the concept of total freedom and the play consequently makes this its central theme. The key philosophy of the play is that humans can interpret the world for themselves without the gods or another power structure telling them what to do; indeed, they are freer when there is no government or belief system. Once in possession of this freedom, people will see what they have a responsibility to do and decide to do it. The theme of freedom shows that the freedom to choose also produces action, as man chooses which course of action will produce the desired outcome. Throughout the play, Orestes wants to free the city and believes he can do this by thinking for himself and acting accordingly. This means that he accepts more responsibility for his actions as they are not the result of situations caused by government or by history.
Past Versus Future
The characters in the play are divided into those who focus on the future and those who are encumbered by the past. The past binds the Argives in servitude to their ruler because they feel bound to make up for their actions of the past. Orestes does not have these encumbrances because he does not accept any responsibility for what happened in the past. He did not make the decisions that caused past events. By asserting his own freedom to think and interpret the world around him pertaining to right and wrong, he is able to look towards the future and create the outcome that he wants and feels responsible for.
Guilt
The Argives feel guilty for the events that happened in the past, and this guilt is caused by the fact that they have not taken full responsibility for them. Their guilt is heavy, all-consuming, and irrational in its scope and intensity; they are burdened by it and are not free in any way whatsoever. Orestes, however, is a different story. While he is the person who kills Aegistheus and Clytemnestra, he commits the murder in order to free the people of Argos; as this is a just and right act, he is not guilty and needs not feel remorse. Orestes knows that if one stands by his or her action and claims it as their own, feeling guilty is not necessary.
Nazi Invasion of France
Although disguised via the play’s structure as a Greek tragedy, a significant theme of the play is the Nazi invasion of France and Sartre's disapproval of the way in which the French government welcomed them and collaborated (the Vichy regime). Sartre was fiercely anti-fascist and saw how the French people suffered due to the war and German occupation. Aegistheus’ usurping of the true ruler and his oppression of the people refer to this occupation. Orestes represents Sartre’s hope that there would be an imminent liberation, and Electra is a stand-in for the Vichy regime due to her ultimate capitulation and collaboration. Sartre endeavors to show the moral, intellectual, and physical dangers that result from being inauthentic and refusing to embrace one’s true freedom.
Authenticity and Bad Faith
To be truly authentic, a person must confront the reality of their total freedom and take responsibility for their actions; they must refuse to utilize frameworks of belief such as religion or philosophy to dictate their actions and choices. They accept that life is essentially meaningless and arbitrary, and that it is only the present moment - not the past or future - that matters. While Orestes is the exemplar of authenticity, Electra is the exemplar of "bad faith," or a person who does not embrace freedom, who is inauthentic, who remains in an impure reflective state of emotion, and whose self-development is ultimately stymied.
Limitations/Absence of the Gods
Sartre was an avowed atheist and such a worldview permeates this text. The gods appear to be largely absent except Zeus, who is limited in the amount of real power he actually has. His power is mostly that of persuasion and banking off of what he knows mankind to be like in terms of their fear of complete freedom. As the critic Timothy Williams notes, "the reader is to understand, of course, that the gods are not real, that they are mere projections of human fear, ceasing to exist for one who no longer fears the burden of absolute freedom." Sartre negates Judeo-Christian beliefs in denouncing the culture of sin/guilt/remorse, and strips the world of the hand of the divine. Commitment and action are choices every man can make (or not make), and those choices are not tied to a moral god propagated by a religion.
"Existence precedes Essence"
This is one of Sartre's most famous existentialist tenets, and it applies quite well to what we see with Orestes. What it means is that a person exists as a hollow void without any qualities or characteristics provided by nature or a god to speak of; rather, it is only when a person makes a decisive choice to be free and to undertake an action that he or she completely avows to truly begin to exist. Orestes is not defined as an autonomous individual until he decides to embrace his freedom and commit the murder of Aegistheus and Clytemnestra that he knows to be right and just. Man is liberated and defined by action, not a priori assumptions about a human being.
