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Metaphors in Science
Oct 1, 2002

Metaphors are generally considered to be poetic linguistic expressions. However, we often use symbolic language and analogies in our daily lives when trying to explain what we see and hear, how we feel and think. Some common examples are time is money, love is a journey, and I feel like a cloud in the air. Scriptures are full of metaphors and symbolism. In both the Bible and the Qur'an, Jesus is introduced as The Word of God. Stories of the Prophets are more than historical facts, for they have metaphorical explanations as well.

Metaphors also play an important role in science. Cognitive scientists, who continue to research how language evolved and which tools the mind uses during this process, state that metaphors are widely used tools. Scientists use language, as well as graphs and equations, to explain their models. Therefore metaphors are essential in learning and teaching science. In this article, we will present a few examples of metaphorical thinking in science and how it guides science in new directions that could lead to breakthroughs. We will be concerned mainly with the machine metaphor that affected the way we picture the world.

A short history

Metaphor derives from the Greek verb methaphora (to transport or transfer). George Lakoff, professor of linguistics at the University of California”Berkeley, and philosopher Mark Johnson explain the essence of metaphor as understanding and experiencing one kind of thing in terms of another. We generally use analogies to make less familiar things appear in guises that are more familiar to us. For example, we try to picture time by associating it with a river. Chemists extend their knowledge of a poorly understood compound by finding similarities with familiar compounds. Biologists use biological mechanisms found in organisms to understand similar mechanisms in others. Luigi Galvani associated the transmission of nerve pulses to an electric current.

Metaphor can be defined as the mapping of a source domain onto a target domain. Throughout the history of science, water waves were used prototypically for understanding light waves. People tried to understand light (target domain) in terms of water waves (source domain). This mapping forced scientists to search for a medium”ether”that could propagate light waves, for water waves were propagated in water.

According to the English physicist Norman Campbell, every scientific theory requires the use of models to understand theoretical terms. For example, in order to comprehend the kinetic theory of gas, we must resort to an analogue model gas behaving as if it were composed of point particles randomly moving in a vessel. Metaphorical models help to improve the scientific imagination. But for scientists to take a model seriously, it must be expressible in terms of mathematical equations.

Sometimes, the symbolic representation of a mathematical relation can lead to a metaphor. For example, the space is time metaphor has an interpretation in molecular biology where millions of years (time) are encoded and contained in DNA (space). In addition, metaphors offer insight into mathematical phenomena. The basic example is the number line, which is the result of imagining numbers as points on a line.

The machine metaphor

From the seventeenth to the nineteenth centuries, the dominant metaphor was the machine metaphor: The world is a machine. This connection was made by Galileo (d. 1642), Descartes (d. 1650), Boyle (d. 1691), and Newton (d. 1727). They imagined the universe as a static, predictable machine. This worldview influenced our beliefs and psyche, as well as the way scientists, philosophers, and other intellectuals thought. Scientists started to think of everything in terms of a machine. Muscles were considered to be force-generating machines, nerves to be electronic machines, and photosynthesis to be a solar-powered machine. Lord Kelvin (d. 1907) characterized the universe as a galactic heat engine.

The machine metaphor led to reductionism in philosophy: If we wish to understand how a machine works, we look into its component parts. Descartes' analytical method of reasoning is based on the assertion that complex phenomena can be understood by reducing them to simple phenomena. Biologists tried to understand living organisms, as well as bodily motions and functions, by reducing them to their constituents. More research was devoted to understanding the nature of genes. Physicist reduced gases' properties to the motion of atoms or molecules. Locke (d. 1704) attempted to understand society by observing the behavior of individuals.

With the picture of a perfect world-machine, belief in a Creator became a logical necessity, since the machine implies an engineer. Even children know, as a part of their personal experience of reality, that a house implies a builder and a watch a watchmaker. As they study the more intricately complex nature of the human body or the ecology of a forest, it is highly unnatural to tell them to think of all these systems as chance productions of irrational processes.

Theologian William Paley (d. 1805) expressed this creationist view on page 98 of his Natural Theology as: There cannot be a design without a designer; contrivance without a contriver; order without choice; arrangement without a thing capable of arranging ... Arrangement, disposition of parts, subserviency of means to an end, relation of instruments to use, imply the presence of intelligence and mind. This Cartesian philosophy connoted the idea that The Hand of God had set the machine in motion at the beginning of creation. As everything had been determined by God already, nothing could be the result of chance. This view is known as determinism.

The computer metaphor

The computer, the current dominant machine, has become the modern era's dominant metaphor. Visionary physicist Edward Fredkin characterizes the universe as a cosmological computer. The universe appears as a network of a dynamic whole whose parts are essentially interrelated. Modern physicists do not consider the atom a basic building block; rather, it is a web of relations that includes human consciousness in an essential way. Modern biologists describe cells as distributive real-time computers. Making good use of the computer metaphor, they focus more on how neurons work together and how each cell interacts with its environment.

Sociologists study individuals and their social relationships. Psychologists and cognitive scientists use the analogy of a computer to understand the mind. Artificial intelligence is just one consequence of such modeling. The universe is no longer seen as a simple mechanical machine, but as a more complex high-tech computer system.

The computer metaphor supports the view of a dynamic universe more than Newton's static universe. James Maxwell's (d. 1879) electrodynamics, the second law of thermodynamics (entropy), and Darwin's (d. 1882) theory of evolution all involve dynamic concepts. Entropy describes the evolution of inanimate matter and states that inanimate systems tend to go from order to disorder. Entropy is an increase in disorder became a root metaphor at the beginning of the nineteenth century.

Biologists describe evolution as a movement toward increasing order and complexity. Darwinian theory attributes biological complexity to the accumulation of mutations by natural selection. One factor that makes Darwinian theory a naturalistic philosophy more than an empirical science is its claims that all of these dynamic processes are a result of random chance. Natural selection is introduced as the mechanism that minimizes the effect of chance. According to Darwinism, probability governs the universe and there is no need for God.

There are probabilities in the quantum world as well. However, probability and uncertainty show the unpredictability of the outcomes of quantum measurements from a human perspective. This probabilistic vision of universe, contrary to Darwinian theory, deepened the consequences of the machine metaphor: God not only set the machine in motion eons ago, but is still governing the process of creation and changing the probability pattern.

Metaphors and paradigm shifts

According to Thomas Kuhn (d. 1996), metaphorical thinking becomes crucial at periods of scientific revolution and gives way to a paradigm shift. Distant analogies are probably the most useful in times of scientific revolution: Newton's metaphor of an apple is a moon is of this kind. However, this metaphor became literal after it was understood that the same gravitational force that holds the apple to Earth is the same one that holds the moon in its orbit around Earth.

Kuhn's paradigm shift and use of metaphors can best be seen in the history of exploring the atom. The atom was conceived first by Democritus (d. c. 370 BCE) as an impenetrable sphere. This analogy was used to explain the behavior of matter until the nineteenth century. Spherical analogy was discarded in favor of Ernest Rutherford's (d. 1937) analogy between the solar system and the hydrogen atom.

The following interpretations followed the planetary model: The nucleus is more massive than the electron (just as the sun is more massive than the planet), the nucleus attracts the electron, this plus the mass relation causes the electron to revolve around the nucleus, and so on. Object descriptions are disregarded, for there is no attempt to match the nucleus with the sun in color, size, or temperature. Then, the atomic nucleus was analogized to a drop of water instead of to a body like the sun.

Now, in quantum mechanics, every particle is considered to be a probability wave, which is an abstract mathematical quantity. Scientists have not yet been able to put these waves into a metaphorical pictorial model, which makes them difficult to comprehend.

Metaphors in revealed texts

The following Qur'anic verses illustrate the use of metaphors in the Qur'an. Speaking of hypocrites who do not believe in God but nevertheless claim to believe, it states: Their parable is like the parable of one who kindled a fire, but when it had illumined all around him, God took away their light and left them in utter darkness”they do not see. Deaf, dumb (and) blind, so they will not turn back. Or like abundant rain from the cloud in which is utter darkness and thunder and lightning. They put their fingers into their ears because of the thunder peal, for fear of death, and God encompasses the unbelievers. The lightning almost takes away their sight. Whenever it shines on them they walk in it, and when it becomes dark to them they stand still. If God had willed, He would have taken away their hearing and their sight. God has power over all things. O people, serve your Lord, Who created you and those before you so that you may guard (against evil) (2:17-21).


Logic and mathematics are not enough to understand science. We need internal mental pictures to grasp new phenomena. When trying to understand unfamiliar phenomena, the mind thinks of them in metaphorical terms. This not only helps to explore new realms for scientific theories, but also can change the view we hold of the world.


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