The Philosophy Book

by DK Publishing

  "It is precisely in knowing its limits that philosophy exists."

  Immanuel Kant

  Intuitions and concepts

  In his most famous work, Critique of Pure Reason, Kant argues that our experience of the world involves two elements. The first is what he calls “sensibility”—our ability to be directly acquainted with particular things in space and time, such as this book you are reading now. These direct acquaintances he calls “intuitions.” Second is what Kant calls the “understanding”, our ability to have and use concepts. For Kant, a concept is an indirect acquaintance with things as examples of a type of thing, such as the concept of “book” in general. Without concepts we would not know our intuition was of a book; without intuitions we would never know that there were books at all.

  Each of these elements has, in turn, two sides. In sensibility, there is my intuition of a particular thing in space and time (like the book) and my intuition of space and time as such (my acquaintance with what space and time are like in general). In understanding, there is my concept of some type of thing (books) and my concept of a “thing” as such (substance). A concept such as substance defines what it means to be a thing in general rather than defining some type of thing like a book. My intuition of a book and the concept of a book are empirical, for how could I know anything about books unless I had come across them in the world? But my intuition of space and time and the concept of substance are a priori, meaning that they are known before or independently of any experience.

  A true empiricist would argue against Kant that all acquaintances come from experience—in other words, nothing is a priori. They might say that we learn what space is by observing things in space; and we learn what substance is from our observation that the features of things change without the underlying thing itself changing. For instance, though a tree’s leaves turn from green to brown, and eventually fall from the tree, it is still the same tree.

  "Thoughts without content are empty; intuitions without concepts are blind… only from their union can cognition arise."

  Immanuel Kant

  Kant split knowledge into intuitions, gained from direct sensibility of the world, and concepts, which come indirectly from our understanding. Some of our knowledge—both of sensibility and understanding—comes from empirical evidence, while some is known a priori.

  Our understanding that entities such as trees undergo change presupposes an a priori grasp of the concept “substance”, according to Kant. Such concepts are the preconditions of our experience.

  Space and substance

  Kant’s arguments show that, on the contrary, space is an a priori intuition. In order to learn about things outside of me, I need to know that they are outside of me. But that shows that I could not learn about space in this way: how can I locate something outside of me without already knowing what “outside of me” means? Some knowledge of space has to be assumed before I can ever study space empirically. We must be familiar with space a priori.

  This argument has an extraordinary consequence. Because space itself is a priori, it does not belong to things in the world. But our experience of things in space is a feature of our sensibility. A thing-in-itself—Kant’s term for a thing that is considered separately from sensibility, and therefore exterior to our minds—may have nothing to do with space. Kant used similar arguments to prove the same thing of time.

  Kant then turns to proving the existence of a priori concepts, such as substance. He asks us first to distinguish between two types of alteration: variation and change. Variation concerns the properties that things have: for instance, a tree’s leaves may be green or brown. Change is what the tree does: the same tree changes its leaves from green to brown. To make this distinction is already to use the notion of substance: the tree (as substance) changes, but the leaves (as the properties of substance) vary. If we do not accept this distinction, then we cannot accept the validity of the concept of substance. We would be saying that any time there is alteration, something “pops” into or out of existence; the tree with green leaves is annihilated at the same time that the tree with brown leaves begins to exist from nothing.

  Kant needs to prove that such a view is impossible. The key to this is time determination. Time cannot be directly experienced (it is not a thing); rather, we experience time through things that alter or do not alter, as Kant has already shown. If we experienced time through the tree with green leaves and also experienced time through the tree with brown leaves without there being any connection between the two, then we would be experiencing two separate real times. Since this is absurd, Kant believes he has demonstrated that the concept of substance is absolutely essential before we can gain any experience of the world. And, since it is through that experience that we learn anything empirical, the concept of substance could not be empirical: it is rather a priori.

  "Only from the human standpoint can we speak of space."

  Immanuel Kant

  The limits of knowledge

  A philosophical position that asserts that some state or activity of the mind is prior to and more fundamental than things we experience is called idealism, and Kant calls his own position “transcendental idealism.” He insists that space, time, and certain concepts are features of the world we experience (what Kant called the phenomenal world) rather than features of the world itself considered separately from experience (what Kant called the noumenal world).

  Kant’s claims about a priori knowledge have both positive and negative consequences. The positive consequence is that the a priori nature of space, time, and certain concepts is what makes our experience of the world possible and reliable. Space and time make our experience mathematical in nature; we can measure it against known values. A priori concepts such as substance make it possible to address questions about nature such as “Is that a substance?” and “What properties does it exhibit and according to what laws?” In other words, Kant’s transcendental idealism is what makes it possible for our experience to be considered useful to science.

  On the negative side, certain types of thinking call themselves science and even resemble science, but fail utterly. This is because they apply to things-in-themselves intuitions about space and time, or concepts such as substance—which according to Kant must be valid for experience, but have no validity with respect to things-in-themselves. Because they resemble science, these types of thinking are a constant temptation to us, and are a trap that many fall into without realizing it. For example, we might wish to claim that God is the cause of the world, but cause and effect is another of the a priori concepts, like substance, that Kant believes is entirely valid for our experienced world, but not for things-in-themselves. So the existence of God (considered, as it usually is, as a being independent of the experienced world) is not something that could be known. The negative consequence of Kant's philosophy, then, is to place quite severe restrictions on the limits of knowledge.

  Transcendental idealism gives us a much more radical way of understanding the distinction between ourselves and the external world. What is external to me is interpreted as not just external to me in space, but external to space itself (and to time, and to all the a priori concepts that make my experience of the world possible). And there are two worlds: the “world” of experience, which includes both my thoughts and feelings, and also includes experience of material things such as my body, or books; and the “world” of things-in-themselves, which is precisely not experienced and so not in any sense known, and which we must constantly strive to avo
id fooling ourselves about.

  Our bodies have a curious role to play in all this. On the one hand, my body as a material thing is a part of the external world. On the other hand, the body is a part of us, and indeed is the medium through which we encounter other things (using our skin, nerves, eyes, ears, and so on). This provides us with one way of understanding the distinction between bodies and the external world: the body as the medium of my sensations is different from other external and material things.

  The Flammarion woodcut depicts a man looking outside of space and time. For Kant, what is external to us is external to space and time also, and can never be known as a thing-in-itself.

  "Human reason is troubled by questions that it cannot dismiss, but also cannot answer."

  Immanuel Kant

  Lasting influence

  Kant’s book Critique of Pure Reason is arguably the most significant single work in the history of modern philosophy. Indeed, the whole subject of philosophy is often divided by many modern thinkers into everything that happened before Kant, and everything that has happened since.

  Before Kant, empiricists such as John Locke emphasized what Kant termed sensibility, but rationalists such as Descartes tended to emphasize understanding. Kant argues that our experience of the world always involves both, so it is frequently said that Kant combined rationalism and empiricism.

  After Kant, German philosophy in particular progressed rapidly. The idealists Johann Fichte, Friedrich Schelling, and Georg Hegel all took Kant’s thought in new directions and, in their turn, influenced the whole of 19th-century thought, from romanticism to Marxism. Kant's sophisticated critique of metaphysical thought was also important in positivism, which held that every justifiable assertion is capable of being scientifically or logically verified.

  The fact that Kant locates the a priori even within our intuitions of the world was important for 20th-century phenomenologists such as Edmund Husserl and Martin Heidegger, who sought to examine objects of experience independently of any assumptions we may have about them. Kant’s work also remains an important reference point for contemporary philosophers today, especially in the branches of metaphysics and epistemology.

  "Reason only has insight into that which it produces after a plan of its own."

  Immanuel Kant

  IMMANUEL KANT

  Immanuel Kant was born into a family of financially struggling artisans in 1724, and he lived and worked his whole life in the cosmopolitan Baltic port city of Konigsberg, then part of Prussia. Though he never left his native province, he became an internationally famous philosopher within his own lifetime.

  Kant studied philosophy, physics, and mathematics at the University of Konigsberg, and taught at the same institution for the next 27 years. In 1792 his unorthodox views led King Friedrich Wilhelm II to ban him from teaching, to which he returned after the king’s death five years later. Kant published throughout his career, but is best known for the series of ground-breaking works he produced in his 50s and 60s. Though a bright and sociable man, he never married, and died at the age of 80.

  Key works

  1781 Critique of Pure Reason

  1785 Foundations of the Metaphysics of Morals

  1788 Critique of Practical Reason

  1790 Critique of Judgement

  See also: René Descartes • John Locke • George Berkeley • David Hume • Johann Gottlieb Fichte • Georg Hegel • Friedrich Schelling • Arthur Schopenhauer

  IN CONTEXT

  BRANCH

  Political philosophy

  APPROACH

  Conservatism

  BEFORE

  c.350 BCE Aristotle argues that society is like an organism, and that man is by nature a political animal.

  5th century St. Augustine of Hippo argues that government is a form of punishment for “original sin.”

  17th century Thomas Hobbes and John Locke develop the idea of the “social contract.”

  AFTER

  19th century French philosopher Joseph de Maistre points out the antidemocratic legacy of Burke since the French Revolution.

  20th century British philosopher Michael Oakeshott develops a more liberal form of conservatism.

  Many a disaffected person cries “It’s not my fault… blame society!” But the meaning of the word “society” is not entirely clear, and it has changed over time. During the 18th century, when the Irish philosopher and statesman Edmund Burke was writing, Europe was becoming increasingly commercialized, and the idea that society is a mutual agreement between its members—like a commercial company—was readily understood. However, this point of view also implies that it is only the material things in life that matter. Burke attempts to redress the balance by reminding us that human beings also enrich their lives through science, art, and virtue, and that while society is indeed a contract or partnership, it is not simply concerned with economics, or, as he puts it, “gross animal existence.” Society embodies the common good (our agreement on customs, norms, and values), but for Burke “society” means more than just the people living now—it also includes our ancestors and descendants. Moreover, because every political constitution is part of “the great primeval contract of eternal society”, God himself is society’s ultimate guarantor.

  Burke’s view has the doctrine of original sin (the idea that we are born sinful) at its core, so he has little sympathy for anyone seeking to blame society for their conduct. Likewise, he dismisses the idea, proposed by John Locke, that we can be perfected by education—as though we are born innocent and merely need to be given the correct influences. For Burke, the fallibility of individual judgment is why we need tradition, to give us the moral bearings we need—an argument that echoes David Hume, who claimed that “custom is the great guide to human life.”

  Tradition and change

  Because society is an organic structure with roots stretching deep into the past, Burke believed its political organization should develop naturally over time. He opposed the idea of sweeping or abrupt political changes that cut through this natural process. For this reason he opposed the French Revolution of 1789, foreseeing its dangers long before the execution of the king and the year-long Reign of Terror. It also prompted him on several occasions to criticize Jean-Jacques Rousseau, whose book, The Social Contract, argued that the contract between citizens and the state can be broken at any time, depending on the will of the people. Another regular target for Burke was the English philosopher and scientist Joseph Priestley, who applauded the French Revolution and pilloried the idea of original sin.

  Despite his scepticism about modern commercial society, Burke was a great defender of private property, and was optimistic about the free market. For this reason, he is often hailed as the “father of modern conservatism”—a philosophy that values both economic freedom and tradition. Today, even socialists would agree with Burke that private property is a fundamental social institution, but would disagree with him about its value. Likewise, ecologically-minded philosophers share his belief in the duties of one generation to the next, but with the new agenda of creating a “sustainable society.”

  Burke condemned the French Revolution for its wholesale rejection of the past. He believed that change should occur gradually—an idea that became central to modern conservatism.

  EDMUND BURKE

  The Anglo-Irish politician Edmund Burke was born and educated in Dublin. From his youth onward, he was convinced that philosophy was useful training for politics, and in the 1750s he wrote notable essays on aesthetics and the origins of society. He served as an English MP from 1766
until 1794, and he was a prominent member of the Whig party—the more liberal of the two aristocratic parties of the day.

  Burke was sympathetic toward the cause of American independence—which sparked a revolution that was entirely justified, in his view—and later became involved in the impeachment trial of Warren Hastings, the Governor-General of India. He remained a scathing critic of colonial malpractice for the rest of his life, and earned a reputation for being the conscience of the British Empire.

  Key works

  1756 A Vindication of Natural Society

  1770 Thoughts on the Present Discontents

  1790 Reflections on the Revolution in France

  See also: John Locke • David Hume • Jean-Jacques Rousseau • Adam Smith • John Rawls

  IN CONTEXT

  BRANCH

  Ethics

  APPROACH

  Utilitarianism

  BEFORE

  Late 4th century BCE Epicurus states that the main goal of life should be the pursuit of happiness.

  Early 17th century Thomas Hobbes argues that a strong legal system, with severe penalties for criminals, leads to a stable and happier society.

  Mid-18th century David Hume claims that emotion governs our moral judgement.

  AFTER

  Mid-19th century John Stuart Mill advocates education for all, arguing that it would improve general happiness.