The major twentieth-century philosophical traditions are notoriously difficult to characterize in a nutshell. Generalizations, especially, are perilous and apt to be misleading. Fortunately, one can begin to sketch a philosophical map, albeit a very rough one, in terms that are largely geographical. One of the major lines that can be drawn on our map divides the philosophical tradition that dominates most of the European continent, known accordingly as Continental philosophy, from the dominant philosophical tradition of England, the United States, and some other countries subject to strong British or American influence (such as Canada and Australia) known as Anglo-American philosophy.
I can offer here only the most rudimentary characterizations of a few of the main strands of Continental philosophy beginning with Phenomenology. Founded around the turn of this century by Edmund Husserl, and developed by Martin Heidegger, Phenomenology is essentially a philosophical method, one that focuses on careful inspection and description of phenomena or appearances, defined as any object of conscious experience, i.e., that which we are conscious of The inspection and description are supposed to be effected without any presuppositions, and that includes any presuppositions as to whether such objects of consciousness are "real" or correspond to something "external," or as to what their causes or consequences may be. It is believed that by this method the essential structures of experience and its objects can be uncovered. The sorts of experiences and phenomena that Phenomenologists have sought to describe are highly varied, including, for instance, time consciousness, mathematics and logic, perception, experience of the social world, our experience of our own bodies, and moral, aesthetic, and religious experience.
Existentialism, unlike Phenomenology, is not primarily a philosophical method. Neither is it exactly a set of doctrines (at least not any one set) but more an outlook or attitude supported by diverse doctrines centered about certain common themes. These themes include the human condition, or the relation of the individual to the world; the human response to that condition (described often in strongly affective and preponderantly negative terms such as "despair," "dread," "anxiety," "guilt," "bad faith," "nausea"); being, especially the difference between the being of persons (which is "existence") and the being of other kinds of things; human freedom; the significance (and unavoidability) of choice and decision in the absence of certainty; and the concreteness and subjectivity of life as lived, over against abstractions and false objectifications.
Existentialism is often thought to be anti-religious (and is, in some of its versions), but there has in fact been a strong current of Christian Existentialism, beginning with the figure often credited with originating Existentialism, the nineteenth-century Danish philosopher Kierkegaard. Existentialism's relationship to Phenomenology is a matter of some controversy, but at least one can say that many of the later Existentialist thinkers, Sartre among them, have employed Phenomenological methods to arrive at or support their specific variations on Existential themes. While Existentialism has been on the wane since the 1960s, it has enjoyed exceptional prominence, even popularity, for a philosophical movement, in part because of its literary expressions by writers such as Sartre, Albert Camus, de Beauvoir, and Marcel.
Structuralism is an interdisciplinary movement united by the principle that social and cultural phenomena, including belief systems and every kind of discourse (literary, political, scientific, etc.), are best understood by analogy with language, itself best understood as a structure of relations among its component parts. Just as in language the crucial determinant of meaning (according to the early structural linguist Ferdinand de Saussure) is neither individual words nor their reference to things outside language but their interrelationships within the linguistic structure, so the crucial element in all social and cultural phenomena is the underlying structure that determines the functions of the various parts. A good deal of Structuralist analysis has been concerned with a kind of unmasking, that is, with revealing political, social, or psychological phenomena as (allegedly) not what they seem or what participants believe them to be but as determined by structures often concealed from view.
This unmasking impulse persists with the group of thinkers sometimes designated Post-structuralists, who both rejected certain presuppositions of Structuralism and added their own more radical ideas about the fundamental role of language in constructing all human perceptions and conceptions of reality. A particular form of this unmasking tendency is Deconstruction, introduced in the work of Jacques Derrida, who is generally counted among Post-structuralists. Any attempt to define Deconstruction must labor in the shadow of Derrida's apparent rejection in advance of all such attempts. Nonetheless, it has seemed fair to many interpreters to characterize it as a form of textual criticism or interpretation whose aim is to unmask and overcome hidden "privileging" that occurs in texts of all kinds. This privileging, for example the privileging of reason, the masculine, the sacred, the literal, or the objective, etc., entails the exclusion, suppression, or marginalization of their oppositespassion, the feminine, the profane, the metaphorical, the subjective, etc.while at the same time it must presuppose these opposites to sustain or even to make sense of the privileged concept. In this way, it is maintained, texts regularly undermine their own assumptions. As a reading technique uncovering alleged hidden agendas behind the ostensible meaning of a text, Deconstruction takes the further step of denying that the text has a definite meaning. This has become a key thesis for the currents of literary theorizing and criticism that followed in Derrida's wake.
Turning to the other dominant twentieth-century philosophical tradition, it is not uncommon to equate Anglo-American philosophy with what is called Analytic or Analytical philosophy. But the term is also used in a broader sense to encompass other movements that have flourished chiefly on British and American soil, for instance Pragmatism, Naturalism, and Process Philosophy. There is much to be said for the wider meaning, which avoids the suggestion that philosophy in England and America is more monolithic than it really is. The equation of Anglo-American with Analytic is also unfortunate from another point of view, in that Analytic philosophy has become the dominant mode of philosophizing in some other areas as well, notably the Scandinavian countries, to say nothing of the inroads it has made in areas where other approaches still dominate the field (the other side of the blurring and bridging of the Continental/Anglo-American boundary), e.g., in Germany. However, given all those qualifications and others, there is no question that Analytic philosophy is the most important philosophical current within the Anglo-American sphere. It is also the one most often contrasted with (and actively opposed to) the Continental movements described above.
What Analytic philosophy is not so easy to say. I believe it is possible to distinguish at least three variants, though they probably represent points on a spectrum rather than discrete alternatives. In the widest and loosest sense, Analytic philosophy is hardly more than a philosophical style, one that takes extreme care with the meanings of words (sometimes with precise definitions of terms and consistency in their use, sometimes with the nuances of ordinary language), that tends to present arguments in meticulous step-by-step fashion (often endeavoring to leave nothing implicit), and that pays close, sometimes minute, attention to logical relations (often using logical symbolism or specialized logical terminology to render such relations transparent). In a narrower sense, "Analytic philosophy" designates a philosophical outlook that holds that the primary task or even (in its more extreme version) the only proper task of philosophythe primary or proper method for attacking philosophical problemsis analysis of one sort or another: of meanings, of concepts, of logical relations, or all of these. We can call this the methodological version. Finally, one may occasionally encounter the term "Analytic philosophy" in contexts where it is reserved for one or more specific doctrines regarding the outcome of correct philosophical analysis. While the Analytic tradition (in either of the two wider senses) owes a great deal to certain specific doctrinal versionsand to major figures who propounded them, such as Bertrand Russell, Ludwig Wittgenstein, and Logical Positivists such as A.J. Ayerit would be incorrect to say that Analytic philosophy is the dominant orientation among British and American philosophers if one has in mind this narrower meaning. In fact, it is not clear that this is true under any but the widest meaning distinguished above.
Common to those who subscribe to the Analytic approach, whether in the broadest sense or a narrower one, is the conviction that to some significant degree, philosophical problems, puzzles, and errors are rooted in language and can be solved or avoided, as the case may be, by a sound understanding of language and careful attention to its workings. (Willard Van Orman Quine, for example, exhibits this strategy in his careful examination of the analytic-synthetic distinction.) This method has tended to focus much attention on language and on its close relative, logic, as objects of study for their own sake. (The relationship between language and logic is itself a question subjected to considerable inquiry and debate.) Detractors are apt to point to this concernthey might say this obsessionwith language and logic as one aspect of the trivialization of philosophy with which they charge the Analytic movement. Many who are generally loyal or sympathetic to Analytic philosophy may agree that it tended to draw philosophy away from "deep" questions. In any case, the last two to three decades have seen, on the one hand, increased self-searching as to the limitations of the Analytic approach, and on the other, more efforts to apply it to such deeper questionsabout the meaning of life, for instance, or the nature of the moral lifein a way that takes them seriously.