It was Hume's skepticism that famously aroused Kant from his 'dogmatic slumbers' - that sleep of sufficient reason, that everything is explicable if a rational gaze sweeps upon it. Hume declared that our knowledge was based on habit, and our morality on sentiment - and Kant went out to prove him wrong, to provide a rational framework of knowledge and morality, which he did in the Critique of Pure Reason and the Critique of Practical Reason, but also of the rational basis of the aesthetic and the religious in the Critique of Judgement. These are known as the 3 Critiques, for obvious reasons.
The Critique of Pure Reason (CPR) is perhaps the most epic of these works, and in it Kant provides an analysis of epistemology and metaphysics, establishing what he calls a 'transcendental' philosophy, which means that there are certain universal structures in the mind that transcend an individual consciousness; there are certain facts that are true for every human mind, and these truths are both necessary and universal for everyone. For example, the reflection of light onto our retinas is (almost) always interpreted as a colour value depending on the wavelength of that light. The 'colour' white is a wavelength very similar for almost every human on earth, and so the fact that 'white' = wavelength x is true for an African or an Asian or a European, whether we know about wavelengths or not.
The 'Copernican Revolution'
Kant's central thesis in CPR is no less than a 'Copernican Revolution' in thought - in the same way that Copernicus confounded traditional astronomy by positing that the Earth goes around the sun and not vice versa, Kant posits that, instead of our minds passively receiving 'sensations' or sense-data from the world and constructing a picture in our minds in that way, we actually project onto the world certain aspects of objectness, in order to see objects. As Kant puts it, instead of "knowledge conforming to objects", in actual fact "objects conform to knowledge."
An example of this is causality. Hume had proven that there is no necessary connection between any two objects in space and time. Snooker balls may go on to hit other snooker balls, and we may theorize about angles and forces of momentum, but just because event B seems to follow event A every single time that we look at it, we cannot categorically say that A 'causes' B. There is nothing in the behaviour of those objects to prove causation without doubt. And if there is doubt, we cannot make a law of causality. Hume was therefore declaring that there is no law of causation - no causality. For you and me and Kant, this is absurd. 999 times out of 1000, when you turn on a lightswitch, the light is going to turn on. But causality is not a characteristic of lights, as Hume proves; but it is a characteristic of the human mind, as Kant proves. Causality is therefore one example of the projection of the human mind onto the world of objects. Gravity is another.
This is certainly a reversal of all previous philosophy, and the problem of the existence of the material world, ever since the Presocratics, has been problematic. Bishop Berkeley, earlier, had proposed that we are actually in the mind of God, as are all objects, so that in fact no things have material existence in any 'real' sense. Hume, after Berkeley, concluded that we cannot have any real knowledge of the material world. The gap between consciousness, knowledge and the material world is too wide. Kant goes some way towards rectifying this.
If he can prove that there are some categories that exist in the mind of all humans, categories both necessary and universal (therefore 'transcendental') in the way we conceive of objects, then he can prove that we have some mental projections onto the world in order to translate 'sensations'(the raw-material of the senses) into concepts or ideas - and therefore knowledge.
The Transcendental Aesthetic (discussed in CPR) is an analysis of the principles of sensory experience. The most basic structures for all sense are space and time. Both space and time are not inherent in the properties of objects; they are projections by the mind on the external world (in the same way that gravity and causality are). The Transscendental Ego is itself timeless, outside time, but projects spatiality and temporality onto the world. In the Kantian system, the three main faculties of the mind are sense, the understanding, and reason. Sense, obviously, is the part of the mind that receives bodily sensations. As Hume previously characterized them, they are mere sensations that are unconnected and are not united by any concept such as self, or time, or causality; they appear in a continuous but unlinked stream. It takes the faculty of the understanding to make sense of these sensations, by characterizing them and identifying them. Kant then declares that the faculty of reason is really the ability to manipulate concepts that arise from the categorization of sensations, but without actual direct experience of those concepts - for example, in geometry, it is unnecessary to understand every single triangle in existence. It is only necessary to understand the concept of triangle, mathematically, so that inferences can be made, using the faculty of reason:
Faculty Function sense receiving sensations ('intuitions') understanding categorizing and identifying sensations to form experiences ('concepts') reason manipulation of concepts without prior experience to new situations
Knowledge is a function of the application of concepts to experience.
The Transcendental Analytic describes how this knowledge is formulated, and analyses the transcendental principles of the understanding. Most concepts come from experience, but there are some that are presupposed in every experience, such as causality. But how do they come to be presupposed? Kant answers that they are classified in certain transcental categories that are true for every person and true for every experience - in fact, a precondition of our having an experience is that it can be classified in one of 12 of these categories. If it cannot, then it is not a experience. Kant famously goes on to prove that this is the case by proving the existence of these 12 categories in his transcendental deduction of the categories. But it is also famously difficult.
The Bounds of Reason
Kant's CPR can be divided into a 'positive' half and a 'negative' half, the Analytic and the Dialectic. The Dialectic is an attempt to put various other philosophies and philosophers in their place, and the transcendental dialectic is highly critical of the pretensions of reason; certain philosophical positions championed by other philosophers who claim to use 'rationality' are attacked as using "the logic of illusion." For example, previous proofs of the existence of God by Anselm, St. Thomas Aquinas and Rene Descartes have all appealed to reason; Kant shows that this claim is false.
The Antinomies (nomos = 'law') are a step towards showing the limits of claims to rationality in 'rational' argument: it is perfectly possible, Kant acknowledges, that a proof for the existence of, say, God can claim to use reason, to be a logical argument. But at the same time it is possible to offer an opposing point of view, also with the claim of rationality. In fact, the antinomies are many metaphysical questions with opposed rational arguments that prove opposite conclusions: for every argument for God's existence, there is one against, and for every one arguing for free will, or the immortality of the soul, there are also arguments against. Kant thereby proves the illusory nature of reason; Reason is the first port of call in our justification of metaphysical 'truths', but we must be careful how we apply it. By showing these opposing arguments, Kant did not want to belittle the faculty of reason, however. He only wanted to stop the petty squabbling of the metaphysicians.
Despite Kant's clear admiration for Newtonian science, the view of the world as operating along clearly delineated mechanical laws of great intricacy, it did not diminish his admiration for a Prime Mover, a Creator. In fact, one of the aims of the CPR is to clearly demarcate the boundaries of reason, to "limit knowledge in order to make room for faith."
Edmund Husserl (1859-1939) introduced a psychological element into philosophy. In Epistemology (the study or theory of knowledge, from episteme) there was a fundamental difficulty (strange as it might seem) in proving the existence of the material world. There is no concrete way, in terms of logic or science, that we can categorically prove the existence of such a material world. Of course, we know it exists, but as soon as we logically analyse this belief, at some stage it seems to fall down.
Epistemologists of the analytic/positivist persuasion tend to get concerned with the minutiae of arguments, whilst Husserl concentrated instead on the things that are more important - we all know that it exists, and even if it doesn't, we can treat it like it does, and the laws of science still operate, so let us consider what is really important in life. His catch-phrase: "To the things themselves!"
Husserl proposed a 'phenomenological method' as a technique for conducting phenomenological analyses. He wanted to make possible "a descriptive account of the essential structures of the directly given." By 'bracketing off' the existence of the material world, the phenomenologist is better able to look at the immediacy of experience, and isolate it from all assumptions of existence, causation or material laws, thereby laying bare its essential structure, the 'essence.'
What does this mean for the philosopher? This phenomenological method restricts the philosopher's attention to the pure data of consciousness, uncontaminated by scinetific or metaphysical assumptions. Husserl's conception of the 'life-world' in his later philosophy also expressed this immediacy - the personal world of the individual as directly experienced, with the ego at the centre and with all of its vital and emotional colourings.
Husserl managed to obtain quite an international following during his editorship of the Annual for Philosophical & Phenomenological Research, and a couple of his adherents were Schiller and Heidegger. Both Schiller and Heidegger held to the phenomenological principle that philosophy is not empirical (i.e. related solely to experience) but is the strictly self-evident insight into the structure of experience. Both of these showed the influence of the phenomenological movement: Schiller in his careful analysis of the role that emotion plays in the morality of mankind, and in his explorations of the human attitudes of resentment, sympathy and love; Heidegger in his investigations of human existence - what it means to be in the world - termed by him being-in-the-world, as well as care, resentment and finitude.
The roots of existentialism, as every schoolboy knows, lie with Kierkegaard and Nietzsche; the former a pessimistic, tormented Christian, the other... erm, a pessimistic tormented atheist. The two central themes which unite these thinkers are:
i) The analysis of being human (ontology, from Greek to on, to be)
ii) The centrality of human choice.
For Karl Jaspers(1883 - 1969), a German who came to philosophy from the study of medicene and psychology, the purpose of existence is the realisation of being; he was preoccupied with theme i), ontology. Philosophizing, for Jaspers, is an internal activity through which one comes to a better understanding of what it is to be, to find or become oneself. It is an attempt to answer the (ultimate) question of what Man is and what he can become. This internal, subjective activity is wholly unlike the objective process of science; solely through thought Man can become aware of the deepest levels of Being.
It is through the 'extreme' situations that define the human condition, thinks Jaspers, that human existence is revealed most profoundly - such as death, guilt, suffering, and conflict. Confrontation with such extremes leads to what he calls "the illumination of existence."
Jean-Paul Sartre (1905-1980) is popularly linked with 'café' existentialism. He was mostly preoccupied with theme ii) - choice; and with choice, responsibility. But in his Being & Nothingness he is concerned for Being (ontology) and the threat of Nothingness, nihilism. But the essence of man's Being is liberty, in his duty of self-determination and his freedom of choice. The negation of this responsibility towards self-determination (the unwillingness to face up to the responsibility of freedom) he calls 'bad faith.' In bad faith, men feebly deny their responsibility to make choices - and therefore to make themselves - and flee from the truth of this inescapable freedom; the person who denies free-will, the person who immerses himself in work or religion, and so on.
Sartre, like Schopenhauer, was less a professional philosopher than a Man of Letters - the large volume of plays and novels that he wrote during his lifetime all assert the existentialist dogma of human freedom, responsibility, and the innumerable mechanisms of escaping it ('bad faith.') The environmental obstacles that men face in trying to realise such freedom, such as poverty, lack of education, bad upbringing and so on, can all be surmounted by conscious decision, thinks Sartre; only in acts of freedom does man achieve authenticity (also an important concept for Heidegger).
This philosophical movement, which received its highpoint in the 1960s and 1970s, also left quite a considerable mark on linguistics, anthropology and literary theory. It all really stems from the Swiss linguist Ferdinand de Saussure, who believed that cultural forms, belief systems and 'discourses' of every kind are best understood by analogy with language or with properties of language when considered from the pure objective viewpoint without subjective time; only from that viewpoint can you analyse its immanent structures of sound and sense. Language is not an accumulation of independent conventions but an interlocking system. Every element is what it is only by virtue of its relation to every other element in the system.
It's impact on literary criticism was profound. Mere interpretation of texts is fruitless; but the examination of structural features of the text puts it on a more sound footing when it comes to analysing a work. In fact, it provides a firmer methodological grounding for the discipline of literary criticism itself, although arguably this structural criticism within literary theory starts with Aristotle's Poetics. The real advance from the structuralists, however, is in its reatment of standard literary devices such as metaphor and metonymy (the placing of one word when meaning another), which are the structural axes of all linguistic communication, and they perhaps reach their highest expressive power in art forms such as poetry.
From Geneva, structuralism was adopted in France by the anthropologist Claude Lévi-Strauss, the literary theorist Roland Barthes, the psychologist Jacques Lacan and the Marxist sociologist Louis Althusser. Into philosophy it continued with the celebrated thinkers Michel Foucault and Jacques Derrida.
Lévi-Strauss concludes that there is nothing really 'primitive' about so-called 'primitive' languages and the 'primitive' people who speak them, since (obviously) any people that can establish or allow to evolve an extremely complex system of signs and signifiers to communicate with each other, and which we can look on with the rationalism of the Western linguist and therefore project linguistic 'rules' back onto, is not the 'primitive' culture that we think; it cannot be so trivialised. Now I suppose this observation is within the orthodoxy of the politically correct.
In addition, the surprising patterns of similar behaviour around the world, for example in ceremonies of rites de passage or the similarity of many African tribes and, say, Shintoism in ancient Japan in their ancestor worship, suggests a similarity of structure of the human mind, with so many common elements. This is a return to the idea of innate ideas which, if you have read about Déscartes and Locke (the old rationalism/empiricism debate) has been rather unfashionable, but in terms of structural linguistics is reinforced by Noam Chomsky. But the analysis of structure is not only mental, for Lévi-Strauss. There is also structure in his analyses of patterns of kinship, mythology, art, religion, ritual and even culinary traditions.
Jacques Derrida wishes the school of deconstruction to be disassociated from any particular trademark method: it is not merely an analytic or critical tool, nor a method in itself, nor an operation performed on a text. Deconstruction, he thinks, resists both translation and interpretation. Which means that, to give you any idea of it on a web site is to encapsulate it. And this is something Derrida doesn't want. But I shall try anyway.
A great deal of the history of philosophy is concerned with finding some ultimate metaphysical certainties or sources of meaning which can characterize (Western) 'philosophy.' But the grounding of philosophy cannot be encapsulated in this historical, metaphysical context, he thinks. Instead, by reading philosophical texts in a particular way (called 'deconstruction') he can expose the metaphysical assumptions or presuppositions that philosophers use - even those who appear to be hostile or dismissive of so-called 'metaphysics.' But instead of offering a metaphysical doctrine of his own, he sought instead to analyse language and to provide a radical, alternative perspective in which even the notion of a 'philosophical' doctrine or thesis is questioned.
Derrida is concerned principally with the use of language in Western thought. He deconstructs Plato's Phaedrus, the father of Structuralism de Saussure, and Rousseau's work on language. Traditionally, speaking is seen as 'above' writing; writing is traditionally seen as being artificial or unnatural in its use of signs - whereas speech is more natural and there is less ambiguity because the speaker's intention is, in the majority of cases, obvious. In speaking, therefore, there is the idea of 'presence' - being bodily there, being mostly unambiguous because of bodily signifiers or whatever.
Why is speaking considered more superior? Perhaps because historically writing, of course, appears on the scene later. Speech is considered, then, traditionally to be a more direct expression of thought or logos, and writing to be a substitute for speech because in writing the intentions of the communicator are more likely to be betrayed.
Derrida, however, disagrees with this traditional view. He argues that the logic of the texts promotes its own refutation - he says the text turns against itself. Speech too, he says, communicates in arbitrary, system-relative and material signs; thus, he overturns the traditional view of speech being 'before' writing.
Since the Presocratics - and especially after Heraclitus' doctrine of the unity of opposites - there is a trend to define a thing relative to its opposite. For instance, what is 'left' is not 'right.' And so we end up with dichotomies for every concept or object in the universe. In the Strcuturalist world, this was best represented by Levi-Strauss' "raw" and the "cooked" in his analysis of primitive peoples. For Derrida, the dichotomies of interest to him are: speech/writing, soul/body, intelligible/sensible, literal/metaphorical, natural/cultural and masculine/feminine.
But, far from defining each in terms of its opposite, he subjects them to an internal critique which destabilizes them. He then asks the Kantian question of what makes these opposites possible in the first place, and this takes language and thought to its outermost limits. From this, Derrida posits new terminology, because the present language is inadequate: archi-writing, différence, textuality, and the trace.
But if, as I stated earlier, deconstruction wishes not to encapsulate things, then don't these new terms threaten to explain the unexplainable? No. Because Derrida purposefully acknowledges that they are inadequate and self-defeating (because they already presuppose existing linguistic structures) and therefore his new terminology is a move away from the structuralism that seeks to enclose things within a system.
Différence is one of the new terms offered by Derrida, which derives from French différer, meaning to "differ" AND to "defer" - so much use is made of this ambiguity in the mother tongue of this French thinker. It is the deferring and slipping from meaning to meaning and moment to moment that occurs continuously in the long linguistic chains in which we communicate.
This is according to Derrida's reading of Husserl, and here Derrida show the impossibility of Husserl's achieving what he set out to do - a rigorously theorized account of structures and modalities of internal time-consciousness; or of the relation between the meaning of the communicator and the language he uses as a network of differential signs. What Husserl wanted was, in effect, to find some base transcendental signifiers within consciousness, meaning or truth, something that would be a constant within consciousness, some 'logocentric' meaning. Derrida show that this is impossible, because of the endless play of differing/deferring.