"Let us then suppose the mind to be white paper, void of all characters, without any ideas; how comes it to be furnished?"
John Locke
As the mind is a blank canvas, or tabula rasa, at birth, Locke believes that anybody can be transformed by a good education, one that encourages rational thought and individual talents.
JOHN LOCKE
John Locke was born in 1632, the son of an English country lawyer. Thanks to wealthy patrons, he received a good education, first at Westminster School in London, then at Oxford. He was impressed with the empirical approach to science adopted by the pioneering chemist Robert Boyle, and he both promoted Boyle’s ideas and assisted in his experimental work.
Though Locke’s empiricist ideas are important, it was his political writing that made him famous. He proposed a social-contract theory of the legitimacy of government and the idea of natural rights to private property. Locke fled England twice, as a political exile, but returned in 1688, after the accession to the throne of William and Mary. He remained in England, writing as well as holding various government positions, until his death in 1704.
Key works
1689 A Letter Concerning Toleration
1690 An Essay Concerning Human Understanding
1690 Two Treatises of Government
See also: Plato • Thomas Aquinas • René Descartes • Benedictus Spinoza • Gottfried Leibniz • George Berkeley • David Hume • Noam Chomsky
IN CONTEXT
BRANCH
Epistemology
APPROACH
Rationalism
BEFORE
1340 Nicolaus of Autrecourt argues that there are no necessary truths about the world, only contingent truths.
1600s René Descartes claims that ideas come to us in three ways; they can be derived from experience, drawn from reason, or known innately (being created in the mind by God).
AFTER
1748 David Hume explores the distinction between necessary and contingent truths.
1927 Alfred North Whitehead postulates “actual entities”, similar to Leibniz’s monads, which reflect the whole universe in themselves.
Early modern philosophy is often presented as being divided into two schools—that of the rationalists (including René Descartes, Benedictus Spinoza, and Immanuel Kant) and that of the empiricists (including John Locke, George Berkeley, and David Hume). In fact, the various philosophers did not easily fall into two clear groups, each being like and unlike each of the others in complex and overlapping ways. The essential difference between the two schools, however, was epistemological—that is, they differed in their opinions about what we can know, and how we know what we know. Put simply, the empiricists held that knowledge is derived from experience, while the rationalists claimed that knowledge can be gained through rational reflection alone.
Leibniz was a rationalist, and his distinction between truths of reasoning and truths of fact marks an interesting twist in the debate between rationalism and empiricism. His claim, which he makes in most famous work, the Monadology, is that in principle all knowledge can be accessed by rational reflection. However, due to shortcomings in our rational faculties, human beings must also rely on experience as a means of acquiring knowledge.
"We know hardly anything adequately, few things a priori, and most things through experience."
Gottfried Wilhelm Leibniz
A map of the internet shows the innumerable connections between internet users. Leibniz’s theory of monads suggests that all our minds are similarly connected.
A universe in our minds
To see how Leibniz arrives at this conclusion, we need to understand a little of his metaphysics—his view of how the universe is constructed. He holds that every part of the world, every individual thing, has a distinct concept or “notion” associated with it, and that every such notion contains within it everything that is true about itself, including its relations to other things. Because everything in the universe is connected, he argues, it follows that every notion is connected to every other notion, and so it is possible—at least in principle—to follow these connections and to discover truths about the entire universe through rational reflection alone. Such reflection leads to Leibniz’s “truths of reasoning.” However, the human mind can grasp only a small number of such truths (such as those of mathematics), and so it has to rely on experience, which yields “truths of fact.”
So how is it possible to progress from knowing that it is snowing, for example, to knowing what will happen tomorrow somewhere on the other side of the world? For Leibniz, the answer lies in the fact that the universe is composed of individual, simple substances called “monads.” Each monad is isolated from other monads, and each contains a complete representation of the whole universe in its past, present, and future states. This representation is synchronized between all the monads, so that each one has the same content. According to Leibniz, this is how God created things—in a state of “pre-established harmony.”
Leibniz claims that every human mind is a monad, and so contains a complete representation of the universe. It is therefore possible in principle for us to learn everything that there is to know about our world and beyond simply by exploring our own minds. Simply by analyzing my notion of the star Betelgeuse, for example, I will eventually be able to determine the temperature on the surface of the actual star Betelgeuse. However, in practice, the analysis that is required for me reach this information is impossibly complex—Leibniz calls it “infinite”—and because I cannot complete it, the only way that I can discover the temperature of Betelgeuse is by measuring it empirically using astronomical equipment.
Is the temperature of the surface of Betelgeuse a truth of reasoning or a truth of fact? It may be true that I had to resort to empirical methods to discover the answer, but had my rational faculties been better I could also have discovered it through rational reflection. Whether it is a truth of reasoning or a truth of fact, therefore, seems to depend on how I arrive at the answer—but is this what Leibniz is claiming?
"Each singular substance expresses the whole universe in its own way."
Gottfried Wilhelm Leibniz
Necessary truths
The trouble for Leibniz is that he holds that truths of reasoning are “necessary”, meaning that it is impossible to contradict them, while truths of fact are “contingent”; they can be denied without logical contradiction. A mathematical truth is a necessary truth, because denying its conclusions contradicts the meanings of its own terms. But the proposition “it is raining in Spain” is contingent, because denying it does not involve a contradiction in terms—although it may still be factually incorrect.
Leibniz’s distinction between truths of reasoning and truths of fact is not simply an epistemological one (about the limits of knowledge), but also a metaphysical one (about the nature of the world), and it is not clear that his arguments support his metaphysical claim. Leibniz’s theory of monads seems to suggest that all truths are truths of reasoning, which we would have access to if we could finish our rational analysis. But as a truth of reasoning is a necessary truth, in what way is it impossible for the temperature on Betelgeuse to be 2,401 Kelvin rather than 2,400 Kelvin? Certainly not impossible in the sense that the proposition 2 + 2 = 5 is impossible, for the latter is simply a logical contradiction.
Likewise, if we follow Leibniz and separate neccesary and contingent truths, we end up with the following problem: I can discover Pythagoras’s theorem simply by reflecting on the idea of triangles, so Pythagoras’s theorem must be a truth of reasoning. But Betelgeuse’s temp
erature and Pythagoras’s theorem are both just as true, and just as much part of the monad that is my mind—so why should one be considered contingent and the other necessary?
Moreover, Leibniz tells us that whereas no-one can reach the end of an infinite analysis, God can grasp the whole universe at once, and so for him all truths are neccessary truths. The difference between a truth of reasoning and a truth of fact, therefore, does seem to be a matter of how one comes to know it—and in that case it is difficult to see why the former should always be seen to be necessarily true, while the latter may or may not be true.
"God understands everything through eternal truth, since he does not need experience."
Gottfried Wilhelm Leibniz
An uncertain future
In setting out a scheme in which an omnipotent, omniscient God creates the universe, Leibniz inevitably faces the problem of accounting for the notion of freedom of will. How can I choose to act in a certain way if God already knows how I am going to act? But the problem runs deeper—there seems to be no room for genuine contingency at all. Leibniz’s theory only allows for a distinction between truths whose necessity we can discover, and truths whose necessity only God can see. We know (if we accept Leibniz’s theory) that the future of the world is set by an omniscient and benevolent god, who therefore has created the best of all possible worlds. But we call the future contingent, or undetermined, because as limited human beings we cannot see its content.
The mechanical calculator was one of Leibniz’s many inventions. Its creation is a testament to his interest in mathematics and logic—fields in which he was a great innovator.
Leibniz’s legacy
In spite of the difficulties inherent in Leibniz’s theory, his ideas went on to shape the work of numerous philosophers, including David Hume and Immanuel Kant. Kant refined Leibniz’s truths of reasoning and truths of fact into the distinction between “analytic” and “synthetic” statements—a division that has remained central to European philosophy ever since.
Liebniz’s theory of monads fared less well, and was criticized for its metaphysical extravagance. In the 20th century, however, the idea was rediscovered by scientists who were intrigued by Leibniz’s description of space and time as a system of relationships, rather than the absolutes of traditional Newtonian physics.
GOTTFRIED LEIBNIZ
Gottfried Leibniz was a German philosopher and mathematician. He was born in Leipzig, and after university he took public service with the Elector of Mainz for five years, during which time he concentrated mainly on political writings. After a period spent travelling, he took up the post of librarian to the Duke of Brunswick, in Hanover, and remained there until his death. It was during this last period of his life that he did most of the work on the development of his unique philosophical system.
Leibniz is famous in mathematics for his invention of the so-called “infinitesimal calculus” and the argument that followed this, as both Leibniz and Newton claimed the discovery as their own. It seems clear that they had in fact reached it independently, but Leibniz developed a much more usable notation which is still used today.
Key works
1673 A Philosopher’s Creed
1685 Discourse on Metaphysics
1695 The New System
1710 Theodicy
1714 Monadology
See also: Nicolaus of Autrecourt • René Descartes • David Hume • Immanuel Kant • Alfred North Whitehead
IN CONTEXT
BRANCH
Metaphysics
APPROACH
Idealism
BEFORE
c.380 BCE In The Republic, Plato presents his theory of Forms, which states that the world of our experience is an imperfect shadow of reality.
AFTER
1781 Immanuel Kant develops Berkeley’s theory into “transcendental idealism”, according to which the world that we experience is only appearance.
1807 Georg Hegel replaces Kant’s idealism with “absolute idealism”—the theory that absolute reality is Spirit.
1982 In his book The Case for Idealism, the British philosopher John Foster argues for a version of Berkeley’s idealism.
Like John Locke before him, George Berkeley was an empiricist, meaning that he saw experience as the primary source of knowledge. This view, which can be traced back to Aristotle, stands in contrast to the rationalist view that, in principle, all knowledge can be gained through rational reflection alone. Berkeley shared the same assumptions as Locke, but reached very different conclusions. According to Berkeley, Locke’s empiricism was moderate; it still allowed for the existence of a world independent of the senses, and followed René Descartes in seeing humans as being made up of two distinct substances, namely mind and body.
Berkeley’s empiricism, on the other hand, was far more extreme, and led him to a position known as “immaterialist idealism.” This means that he was a monist, believing that there is only one kind of substance in the universe, and an idealist, believing that this single substance is mind, or thought, rather than matter.
Berkeley’s position is often summarized by the Latin phrase esseest percipi (“to be is to be perceived”), but it is perhaps better represented by esse est aut perciperi aut percipi (“to be is to perceive or to be perceived”). For according to Berkeley, the world consists only of perceiving minds and their ideas. This is not to say that he denies the existence of the external world, or claims that it is in any way different from what we perceive. His claim is rather that all knowledge must come from experience, and that all we ever have access to are our perceptions. And since these perceptions are simply “ideas” (or mental representations), we have no grounds for believing that anything exists other than ideas and the perceivers of ideas.
"There is no such thing as what philosophers call material substance."
George Berkeley
Causation and volition
Berkeley’s target was Descartes’ view of the world as elaborated by Locke and the scientist Robert Boyle. In this view, the physical world is made up of a vast number of physical particles, or “corpuscles”, whose nature and interactions give rise to the world as we understand it. More controversially, for Berkeley, this view also maintains that the world causes the perceptual ideas we have of it by the way it interacts with our senses.
Berkeley has two main objections to this view. First, he argues that our understanding of causality (the fact that certain events cause other events) is based entirely on our experience of our own volitions (the way we cause events to happen through the action of our wills). His point is not simply that it is wrong for us to project our own experience of volitional action onto the world—which we do when we say that the world causes us to have ideas about the world. His point is that there is in fact no such thing as a “physical cause”, because there is no such thing as a physical world beyond the world of ideas that could possibly be the cause of our ideas. The only type of cause that there is in the world, according to Berkeley, is precisely the volitional kind of cause that is the exercise of the will.
Berkeley’s second objection is that because ideas are mental entities, they cannot resemble physical entities, because the two types of thing have completely different properties. A painting or a photograph can resemble a physical object because it is itself a physical thing, but to think of an idea as resembling a physical object is to mistake it for a physical thing itself. Ideas, then, can only resemble other ideas. And as our only experience of the world comes through our ideas, any claim that we can even understand the notion of “physical things” is mistaken. What we are re
ally understanding are mental things. The world is constructed purely of thought, and whatever is not itself perceiving, exists only as one of our perceptions.
"If there were external bodies, it is impossible we should ever come to know it."
George Berkeley
The cause of perception
If things that are not perceivers only exist in so far as they are perceived, however, this seems to mean that when I leave the room, my desk, computer, books, and so on all cease to exist, for they are no longer being perceived. Berkeley’s response to this is that nothing is ever unperceived, for when I am not in my room, it is still perceived by God. His theory, therefore, not only depends on the existence of God, but of a particular type of God—one who is constantly involved in the world.
For Berkeley, God’s involvement in the world runs deeper than this. As we have seen, he claims that there are no physical causes, but only “volitions”, or acts of will, and it follows that only an act of will can produce the ideas that we have about the world. However, I am not in control of my experience of the world, and cannot choose what I experience—the world simply presents itself to me the way it does, whether I like it or not. Therefore, the volitions that cause my ideas about the world are not mine; they are God’s. So for Berkeley, God not only creates us as perceivers, he is the cause and constant generator of all our perceptions. This raises a number of questions, the most urgent being: how is it that we sometimes perceive things incorrectly? Why would God want to deceive us?
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