Existentialism - Being and Nothingness

"Existence precede's essence" - Jean Paul Sartre, Being and Nothingness

Existentialist's believe that you are here in the moment and all that matters is that we know we exist.
They reject Descartes' "Cogito ergo sum" - "I think therefore I am", instead they support "I am therefore I think" reducing it down to "I think", which essentially is "there are thoughts". They reject also the narrative "I", as they do not regard people as self contained; rather that we are a composite of other people around us. You wouldn't be you if you were just on your own.  Consciousness is not individual, there is no "I", the transcendent Cartesian ego cannot be found anywhere.

The journey begins with Kant, he outlines in his famous work 'The Critique of Pure Reason' that
existence is not a predicate (purpose/result) of consciousness or being. Kant believed that existence is a pre-condition of consciousness, and that consciousness is not a proof of existence anyway, consciousness "just is", it's not the result of anything, or the cause of a particular thing.

How could there not be consciousness? The opposite of consciousness is unconscious, which is a mind without properties, therefore we cannot stand outside of consciousness. Just how the opposite of nothing is not something, similarly to how dog is not the opposite of cat, nor is it a not-cat.

Husserl wrote a famous book titled "Psychology from an empirical standpoint" which became the foundation of modern phenomenology*. The essence of his phenomenology is the study of immediate data of consciousness. For Husserl it makes no difference whether the ideas I have represent the real world, or whether they are hallucinations. For example, there is a table in front of me, whether this phenomena is real or an hallucination is irrelevant, to Husserl it did not matter.
*phenomenology is the study of the structure of experience and consciousness.

Heidegger proclaimed the end of the metaphysical age from Plato to Husserl, the change began in the 1790s with Kant who they believed triggered the destroying of metaphysics. The Logical positivists in Vienna and Cambridge were saying the same thing at the time. In the metaphysical age, objects exist independently of mind, they 'subsist', and the role of the mind is to kind of mirror the structure of reality.

The 'mission' of philosophy was to establish the 'reality' of the existence of the ego as an object within an external world and to describe the nature of this reality. (Science)

The primary idea in the metaphysical age is to make thoughts corresponding with underlying or hidden substrata of independently subsisting reality, such as Descartes' 'God' or Schopenhauer's 'Will'.
Thoughts that correspond with reality are truth statements.
"The truth is out there" - Truth is agreement of knowledge with objects. Objects are eternal and prior to mind (Aristotle) or can be mind dependent (Kant) but either way according to the metaphysicians they exist.

After Heidegger there is no absolute truth there are only subjective "weak truths" or "practical truths" or "convenient truths" and these are the reliable truths which are necessary to being and being is always concrete and specific: "always being in the world" or "being there" (Dasein)

Dasein is in your mood or emotion.
Heidegger believes that your mood is you and emotion is authentic being.

Truth is no longer a matter of matching thought to reality, but of making reality which is seen as true post-hoc. (Latin for "after this") There is no idea of a 'correct truth' in which one culture has access to, there are many truths which are specific to the desires and moods of an individual.

Heidegger's Project was to clear away all philosophical terminology and throw away the concepts and systems since Socrates, he literally burned them, in order to liberate himself from objectification and metaphysics.  Heidegger was a Nazi, who believed to live an "authentic life" would be to live a simple life in the forest. The 'good life' consisted of real ale, organic foods, fertile women and physical strength. This was his dasein.

Like Nietzsche, Heidegger believes Socrates corrupted Western Civilization. Heidegger invents an original set of terms in order to speculate about the exterior world.

Existence and Time

Dasein means "being there". 
Like Husserl, Heidegger is not interested in consciousness.

Being is not an abstract idea, we are always thrown in to things, thrown in to the world, thrown in to doing jobs, and we are always in the middle of some sort of task, like a roller-coaster ride; everything is always moving. Freedom and authenticity for Heidegger is complete absorption in a task-
when you are fully engaged in a task, you no longer exist.

Existence = Boredom 
Boredom is the "problem of being", thus Heidegger would advise you find your Dasein as the opposite of boredom is Dasein, the lack of boredom is non existence (engagement in Dasein).

Existence requires time
Without time there would be no boredom, but with infinite time there would be infinite boredom. 
The perception of "lack of time" creates a sense of urgency, it force's you to just do it. Dasein is non reflective and unthinking, you are in the moment. Dasein is not thinking.

There are three aspects of time
(1) Attunement - expressed as mood, this is the reflection on the past associated with guilt
(2) Being for itself, or being there - this is caring about the task in hand, the present mode
(3) Directedness - this is a reflection on the future which is associated with the mood of dread, fear of the future.

Past = Guilt
Present =Boredom (dasein)
Future = Fear

The core of existentialism is that existence is everything, people don't have essences. We don't have to act in certain way just because we are students - life is there to be made, and it will be made for you if you don't make it for yourself.

Existential saints are people who are madly committed to something, but to do something in a moderate way to please others or fit in is an existential sin. The only way to free yourself is to have an overriding desire, and passion. Existential hell is doing something because you have to.