Jean-Paul Sartre adopted and adapted the methods of phenomenology, in particular Heidegger's work. Like him, Sartre wanted to develop an ontological description of what it is to be human. He expounded his theories in La Transcendence de l'Ego (1936), L'Être et le néant (1943), and L'existentialisme est un humanisme (1946). He also believed that our ideas are products of our real-life experiences and that novels and plays that describe fundamental experiences have value for philosophical theories as well as discursive essays. Thus he wrote several novels and plays that were later followed by a school of the literature of the absurd
"Essence precedes existence." Sartre.
Sartre believed that we all have options and therefore freedom. Even in the face of the inevitable, we can choose to do nothing, run away or risk our lives. This freedom brings with it power, but also responsibility. We are condemned to be free, according to the author, and we have to face it if we want to be moral. Individuals are responsible for what they choose, but they live with a constant existential concern because they are aware of the limits of knowledge and mortality.
The corollary of this argument from human freedom is that if God exists the human is not free and vice-versa. Atheism is an integral part of Sartre's philosophy. This means that in a world without God life has no meaning beyond individual human goals.
For his part, Heidegger thought that Sartre had appropriated his work to return it to the previous subject-object philosophy of Descartes and Husserl. This is exactly what Heidegger wanted to free philosophical thought from.
Maurice Merleau-Ponty set out to develop a radical description of bodily experience, mainly in perception studies. He argued that this phenomenon could not be understood by the philosophical tradition because it tended to move only between two flawed alternatives: empiricism and intellectualism.
Another traditional dichotomy that Merleau-Ponty criticizes is the distinction between subject and object. Generally we maintain a distinction between ourselves and the objects of the world and we can suggest that we are free and they are determined. He also differentiated between the empirical facts of our actions and the reasons that transcend those behaviors. This distinction between object and consciousness is dualism.
"... he who sees and he who touches is not exactly himself, because the visible world and the tangible world are not the world as a whole." Merleau-Ponty
In his work Le Visible et l'Invisible (1988), the author tries to make a transition from a phenomenology of consciousness (an analysis of how the objects that we perceive are presented to us) to a philosophy of Being: that which allows the possibility of existence.
Merleau-Ponty uses linguistics and structuralism to criticize Sartre who gave a meager role to language. He based himself on Lacan, who suggested that the unconscious is structured as a language, on Claude Levi-Strauss, a structuralist anthropologist, and on Saussure. Levi-Strauss believed that Merleau-Ponty's work was a synthesis of structuralism and phenomenology.
Claude Levi-Strauss borrowed the term 'structuralism' from Ramón Jakobson, but it was he himself who expanded it beyond its linguistic origin and demonstrated that it was a general way of approaching human life because it could be applied to all aspects of culture. It is the idea that symbolic practices cannot be considered scientific objects without introducing new types of entities not recognizable by traditional metaphysics.
"The wise man is not the one who provides the true answers, but the one who asks the true questions." Claude Levi-Strauss
Structuralism encourages philosophers to develop a new ontology by redefining what it means to be different and identical, to be single or multiple, to be successive or present. It also forced a reconsideration of the nature of 'meaning' (now not objective but the effect of actions) and
'subjectivity' (no longer analyzed as origin but as function).
Levi-Strauss opposes thinkers who imagine logical coherence, with anthropologists who rely on verifiable facts. He affirms that we will only know what there is to know if it is recognized that practices very distant from scientific knowledge, such as myths and rituals, are variants of this same knowledge. As an anthropologist he defined anthropology as the type of knowledge that uses different forms of knowledge to produce particular truths. Another type of science.
Michel Foucault starts from Kant's epistemological theory to reverse it. The German philosopher maintained that the same criticism that revealed the limits of our power to know could also reveal the necessary conditions for its exercise. He argued that what appeared to be circumstantial features of human cognition (such as the spatial and temporal character of perceptual objects) are actually necessary truths. Foucault suggests that instead of asking what is necessary in the apparently contingent, we ask what is circumstantial in what is apparently necessary. He focuses his questions on the modern human sciences (biology, psychology, sociology) that claim to offer scientific truths about nature but are, in fact, expressions of the politics or ethics of a particular society.
In his Histoire de la folie à l'age classique (1961), a study of the concept of madness as
'mental illness' in Europe, he argues, it was not an improvement over earlier notions. He claimed that the alleged neutrality of modern insanity treatments is in fact used to control insanity's challenges to conventional bourgeois morality. In short, what is presented as a scientific discovery is the product of a questionable social and ethical ideology.
"The characteristic of knowing is neither seeing nor demonstrating, but interpreting."
In the work that made him famous Les mots et les choses (1966) Foucault argues that from Descartes to Kant representation was assimilated to thought: thinking was using ideas to represent the object of thought, as on a map. It is the principle that we know that our thoughts represent what we know just as the map represents the territory. Furthermore, we can alter the structure of an idea to improve representation of an object similar to redrawing a map. Foucault insists that Kant introduced a new vision by proposing that representation itself could have its origin in something other than representation.
In L'ordre des choses (1966) he presents the two main features of thought after Kant: the return of language and the 'birth of man'.
Language in classical thought (Descartes a Kant) was an instrument of thought: a physical representation of ideas and meaningless except in relation to them. After Kant, language has an independent and essential role. It is freed from its subordination to ideas and can function (as in the Renaissance) as an autonomous reality without a system of representations linking it to the world. Furthermore, Foucault suggests that language is a truth in itself, communicating nothing but its own meaning. (In contrast to the Renaissance, however, there is no underlying divine Word that gives a single truth to the words of the language.)
The notion of the 'birth of man' is explained by the fact that in the classical age humans were supposed to receive mental representations; on the other hand, for Kant's transcendental idealism these perceptions are mental products. Foucault exemplifies this idea with his example from Descartes. In his famous phrase: "Je pense donc je suis", Descartes relates the being with its representation, that is, ontology with mental perception. This was logical within classical epistemology that equated thinking with representing. Post-Kantian philosophy, however, affirms that thinking is a creative activity and thus we cannot pass from representation to thinker. We cannot go from "I think" to "I am" because the content of our reality (what I am) is always more than the content of our thinking because living, working, speaking, etc. take us beyond thought.
Kant tries to unite the two traditions proposing that the 'I' consciousness must be an empirical object of representation and at the same time a source of transcendental representations. The project of modern philosophy is to test whether this can be possible. Foucault believes that it is not possible and reviews the post-Kantian philosophers to demonstrate it.
According to Foucault, Naturalism and Marxism reduce the transcendental to the empirical: the former explains knowledge in terms of the natural sciences; the second appeals to the social sciences. Foucault points out that both ignore the terms of the problem: that the person is empirical and transcendental at the same time.
Husserl based knowledge of empirical truths on the transcendental subject. Foucault replies that thought is no longer pure representation as in Descartes and empirical facts cannot be separated from whom we are.
Sartre and Merleau-Ponty's existentialist phenomenology focus on the concrete reality of human-in-the-world. But Foucault believes that this is a subtle way of reducing the transcendental to the empirical.
Hegel, Nietzsche and Heidegger tried to solve the problem of the human dual status treating it as historical reality. But the difficulty remains that the human has to be the product of historical processes and at the same time the origin of history. If we treat humanity as a product, its reality is reduced to something non-human; if we insist on a human return to origins, its place in the empirical world no longer makes sense. It is the modern paradox of the human as originated and origin. Foucault suggests that the modern search for origins provides us with a deeper sense of the ontological meaning of time. This is more evident in the thinking of Nietzsche and Heidegger who reject the vision of Marx and Hegel of the return to the origin as redemption of being and propose that it leads us to a confrontation with the nothingness of existence.
Jacques Derrida was the promoter of 'Deconstruction', a critique of the Western philosophical tradition, in particular of phenomenology, existentialism and structuralism. It generally works using specific texts that try to expose and then subvert the binary oppositions that underlie our main ways of thinking: presence / absence, speech / writing ...
"There is nothing outside the text." Jacques Derrida
His metaphysics describes the return to origins found in metaphysicians from Plato to Husserl, looking for a foundation on which to build their theories. This is how they conceive of good before evil, the positive before the negative, purity before impurity, the simple before the complex, the essential before the accidental etc ... Derrida warns that in these oppositions there is always a hierarchy : one party subordinate to the other. Deconstruction aims to undo the classical opposition to end the system.
However, this same methodology deconstructs itself because it no longer starts from the possibility that the observer may be external to the object under examination.
Jean-Paul Sartre (1905 - 1980)
Claude Lévi-Strauss (1908 - 2009)
Paul-Michel Foucault (1926 - 1984)
Jacques Derrida (1930 - 2004)