How we change what others think, feel, believe and do
Existentialism is an atheist philosophy that casts us alone in a self-created world, where we are responsible for everything we perceive. It sets us free but gives us no direction. Though it started in the late 19th century, it grew with secular culture and was most popular in the 1950s.
It has plenty of scope for creating a confused and dismal life, where we fall into despair about meaninglessness of it all. It can also lead to hedonism, where we work on the principle that we might as well indulge ourselves as there is little else to give us reason for existence.
The major philosophers associated with Existentialism include Soren Kierkegaard, Jean-Paul Sartre, Albert Camus, Fydor Dostoyevsky and Friedrich Nietzsche.
Existence precedes essence
'Essence' is how you are described, such as having certain personality characteristics, your job, your relationships and so on. For any of this to happen, you must first exist. In fact your true essence comes from what you consciously think and choose, not how others describe you.
As an independent person, without obligation to God or others, you are free to do whatever you choose. You make you, not God and not other people. You are not the stereotypes assigned to you by others. By this, you are responsible for your thoughts and actions. Nobody 'makes' you do anything. You are what you do. You are totally free, and cannot blame your life on anyone but yourself.
When you act in a way that is aligned with your self-created essence and freedom, then you are acting authentically. When you act in ways that you think will please others or conform with social stereotypes, then you are being inauthentic.
Authenticity can be difficult. First, you must know your essence, then you must enact it, even if it causes disapproval. Concerns for authenticity makes choice critical and tricky.
There is no meaning in the world, other than the meaning we choose. Meaning does not exist without people, and each person chooses their own meaning. A conclusion of this is that the world, by itself, meaningless, as is life. Meaningless can be very difficult, as we all seek meaning in life, and can lead to a depressive position. This need not be the case, however, as we have freedom of choice.
The self is separated from other people. We are individuals, not a joined part of a collective. We must face the world alone. These can give two forms of alienation: first, that we feel alienated from others, and also that others can seem alien and different to us.
This can be uncomfortable as our need to connect with others can create an aching separation tension with a continuing sense of isolation. In this way it adds to the depressive nature of existentialism.
There have been several definitions of this, but in general facticity is about reality (as opposed to idealism), such as the contrast between a thing and its context. It is about how things exist in their environment. It is also what we can see and discover about people, not the assumptions we make about them. Discovering our essence may require transcending facticity as we journey inwards.
Derived from phenomenology, the 'Other' (usually capitalized) is at its simplest just another individual whose existence acts as both as a reflection and differentness that confirms one's existence. The unspoken conversation is something like 'you are not-me'. By seeing you, I realize that you are not me and hence I know that I exist.
Because we cannot know the minds of Others, they appear strange and may feel threatening. Then when we see ourselves in them, we feel that we are also unfamiliar in some way. When an Other gazes at us, we feel particularly disturbed as we can only guess how they are perceiving us.
What is sometimes 'existential angst' is a form of dread, fear or discomfort that we may feel as we contemplate the existential existence, with the limitations of being human, of being ultimately alone and being solely responsible for our own lives. Because we know we are capable of doing anything, we fear doing things that we do not want to do, the ultimate of which is suicide. In fearing such things we have to contemplate them, which only makes our discomfort worse.
Existential despair is the ultimate depressive position as we lose hope, particularly in contemplating our identities crumbling into nothingness. Existentialism easily falls into this as the negative aspects described above overwhelm us. For example a piano-player who gets arthritis and can no longer play feels that who they are is ceasing to exist.