Existentialism, also known as existentialism, is one of the main schools of contemporary western philosophy. It was first put forward by Marcel, the founder and existentialist of French theism. This is a very broad school of philosophy, which mainly includes theistic existentialism, atheistic existentialism and existential Marxism. Its fundamental point of view is to regard the irrational consciousness activities of isolated individuals as the most real existence and as the starting point of all his philosophy. Existentialism takes people as the center, respects people's individuality and freedom, and thinks that people live in a meaningless universe, and human existence itself is meaningless, but people can create themselves and live wonderfully on the basis of existence. Its most famous and clear initiative is Jean-Paul Sartre's motto: "Existence precedes essence". It means that there is no natural morality or soul except human existence. Morality and soul are created by human beings in existence. People have no obligation to abide by certain moral standards or religious beliefs, but they have the freedom to choose. Judge a person by his behavior, not by who he is, because a person is defined by his behavior. Sartre denied the existence of God or any other predefined rules. Jean-Paul Sartre opposes any "resistance" factors in life, because they narrow the space for people to choose freely. If there is no such resistance, then the only problem a person has to solve is which way he chooses to take. But man is free; Even if he is deceiving himself, there is still potential and possibility. Sartre also put forward: "Others are hell". This view seems to contradict the view of "freedom of choice". In fact, everyone has the freedom to choose, but everyone has an unshirkable responsibility for the result after choosing. In the process of choosing, the biggest problem people face is the choice of others, because everyone has the freedom to choose, but everyone's freedom may affect the freedom of others, so it is called "others are hell".

The discussion of existentialism in The Unbearable Lightness of Life is mainly carried out from three aspects:

Absolute freedom of choice —— Jean Paul Sartre's most famous existentialism sentence "Existence precedes essence" aims to show that there is no natural morality and soul except human existence. Morality and soul are created by human beings in existence. People have no obligation to abide by certain moral standards or religious beliefs, but they have the freedom to choose. The protagonist is a good practitioner of this view. Thomas has a "must" persistence in his medical career, and he is also full of curiosity and desire to conquer women's bodies with enthusiasm. He walks freely among more than 200 mistresses (especially after becoming a glass washer) with an unrestrained and bohemian attitude and a way of making love without emotional input. "He has tried his best to design a lifestyle for himself. No woman can ever come to his house with a box." This attitude and way is based on complete personal will, and it is liberalized from the psychological will (sensibility) of people themselves; Secondly, this way of life is like Sartre's opposition to any "resistance" factor in life. It is specially formulated to avoid "narrowing people's choices". No responsibility or commitment, completely free. It is not difficult to understand that he divorced with the mood of "being as happy as others celebrating marriage" and made a decision not to see his own son in this life in a short time. Sabine, Thomas' closest lover, her philosophy of life is to constantly "betray" and resist kitsch. "'betrayal'. My father and primary school teachers taught us that this is the most hateful thing imaginable in the world. But what is betrayal? Betrayal is leaving your position. Betrayal is to get rid of the original position and throw yourself into the unknown. Sabin thinks that nothing is more wonderful than being born in the unknown. " After graduating from high school, I went to Prague and felt a little comfort for betraying my home. Marry a mediocre Prague actor in order to betray (father, husband's father); Similarly, "once again, I am full of desire for betrayal: betrayal of myself." Announce your departure to your husband; In Geneva, she once again chose to "ride on Flantz and betray Flantz" for her loyal lover Flantz. As an artist, she has been struggling with "socialist realistic painting" all her life, because she thinks it is also a kitsch, so she must fight it. On the surface, her painting is always a perfect real world, but behind it, like a rag in the background of the stage, people can see different things, mysterious or abstract things. ..... On the surface is an obvious lie, but behind it is a hidden truth. "No matter Thomas or Sabin, they are constantly making choices, seeking and determining their sense of existence in a series of free choices.

Others are hell-Sartre put forward: "Others are hell". This view seems to contradict the view of "freedom of choice". In fact, everyone has the freedom to choose, but everyone has an unshirkable responsibility for the result after choosing. In the process of choosing, the biggest problem people face is the choice of others, because everyone has the freedom to choose, but everyone's freedom may affect the freedom of others, so it is called "others are hell". Previously, Thomas specially designed a "light" lifestyle for himself, so that he could wander among many lovers without any burden and adhere to the "three" principles formulated by himself. However, Teresa's arrival broke and finally ended her own rules of the game. He took him in and married her, and his leisurely swimming style collapsed step by step until he suddenly realized the weightlessness he had never felt before. Teresa is not Thomas' lover or wife. "This little-known girl, he felt a kind of inexplicable love. To him, he is just a child who is put down the river in a basket coated with resin so that he can carry her to bed. " Teresa chose Thomas, whether out of love or sympathy, Thomas also chose her. Choice is free, but everyone has an unshirkable responsibility for the result after choice. Thomas wants to maintain his way of life, but whenever he holds Teresa in his trembling hands in the middle of the night, he feels deep sympathy and guilt, and he begins to have scruples and ties. Teresa even felt a little worried when he danced with his colleagues. After the Russian occupation, they refused the help of the director of the Swiss hospital without hesitation, fearing that Teresa could not survive abroad, but chose to come to Zurich at Teresa's request and will. Later, in pursuit of Teresa's departure, they chose to give up their superior living conditions and return to occupied Prague. Finally, they chose to live alone in the village for the protection of Teresa. In this series of departure and choice, it can be said that it is free, and it can also be said that it is not free because it is bound. The original "light" lifestyle made him unbearable, so he thought that the lightness that Teresa recovered after leaving did not come as scheduled, but the feeling of weightlessness suddenly came, and his love for Teresa made him bear and bear the burden.