Tag Archives: Aristotle

Arts, Philosophy, Science

Philosophy: The Scientific Revolution

RENAISSANCE

Intro: Although the Renaissance was primarily an artistic and cultural movement, its emphasis on free thinking challenged the authority of religion, and paved the way for an unprecedented age of scientific discovery

Tradition undermined

THE Scientific Revolution began with the publication in 1543 of Nicolaus Copernicus’s De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), which presented evidence contradicting the notion of a geocentric universe. A description of this is given at the end of this article.

That same year, Andreas Vesalius published De humani corporis fabrica (On the Fabric of the Human Body), which overturned many orthodox ideas in anatomy and medicine. What followed was a profound change in the approach to enquiry into the natural world. Conventional wisdom, including the dogma of the Church, was no longer blindly accepted, but challenged. Even the work of Aristotle, who had initiated the idea of natural philosophy based on methodical observation, was subject to scientific scrutiny.

At the forefront of this scientific revolution were philosophers such as Francis Bacon, whose Novum Organum (New Instrument) proposed a new method for the study of natural philosophy – systematically gathering evidence through observation, from which the laws of nature could be inferred. But there was also a new class of thinkers and scientists, including Nicolaus Copernicus, Johannes Kepler, and Galileo Galilei. Galileo challenged dogma more than most by proving that the Earth orbits the Sun, and fell foul of the Church for his efforts.

The discoveries made by these scientists, and the methods they used, laid the foundations for the work of Isaac Newton in the following century, and also influenced philosophers such as Descartes, Spinoza, and Leibniz, who helped to shape the ideas of the Age of Enlightenment.

One Cause Only

Central to Aristotle’s philosophy was the concept of the “four causes” (see article). The new scientific methods of the 16th and 17th centuries rejected these, especially the concept of a “final cause”, or purpose. Instead it was proposed that there are only “efficient causes” in nature – i.e. physical causal triggers. Although this is closer to the modern idea of cause and effect, the idea had first been proposed by the Atomists some 2,000 years earlier (see article).

Laws of nature

The theories of Copernicus and his contemporaries heralded a new era of scientific discovery. Religious authority was undermined, but so too was the orthodox concept of the laws that governed the universe, which were based on Aristotelean cosmology and physics. In this new atmosphere of scientific enquiry, conventional assumptions were replaced with laws of nature derived from empirical evidence of observation and experiment.  

The New Method

Induction

Bacon described a method of scientific enquiry using the process of induction, inferring a general rule from particular instances. For example, the rule that water boils at 100C can be inferred because this is the case in every instance.

Experimentation

Often, it is not enough simply to observe in order to come to a scientific conclusion. The scientific method pioneered by Islamic philosophers involves conducting controlled experiments to get reproducible results.

Galileo Galilei once said: “In science the authority of thousands of opinions is not worth as much as the reasoning of one individual.”

Sunspots – The detailed study of sunspots made by Galileo and others showed that these are inherent features of the Sun. These observations contradicted the Aristotelean idea of the perfection of objects in the heavenly spheres.

Gravity – Although it may only have been a thought experiment, Galileo dropped two balls of different weights from the Tower of Pisa to show that they fell at the same speed. This refuted Aristotle’s assertion that heavy objects fall faster than lighter ones.

Elliptical orbits – Once it was proven that the Earth orbits the Sun, the orbits of the planets could then be explained. Kepler discovered that the orbit of Mars was not circular, but an ellipse, and concluded that all the planets had elliptical orbits.

THE GEOCENTRIC UNIVERSE

Outside the orbit of the Moon lies the celestial region in which the Sun, the planets, and the stars move in orbits at various distances from the Earth. Unlike the sublunary region, the celestial region is made from an incorruptible substance, which Aristotle calls the “quintessence”, or fifth element. According to Aristotle, the natural movement of the earthly elements is up or down, towards or away from the centre of the Earth. By contrast, the natural movement of things in the celestial region is circular. What’s more, earthly elements tend towards a position of rest, while celestial movement is unceasing. Thus, Aristotle reasoned that the stationary Earth, although imperfect, is at the centre of the cosmos.

Beyond the Moon’s orbit, Aristotle identified 55 concentric spheres to which the celestial objects are attached. As they radiate away from the Earth, the outer spheres draw closer towards perfection, stretching into spiritual realms that have no material existence. The universe, for Aristotle, is a perfect form, and cannot have come into being at any one time: it is eternal, unchanging.

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Arts, Philosophy

Philosophy: Purposes in nature

TELEOLOGY

Intro: According to Aristotle, everything that exists has a final cause, or purpose – what in Greek is called a telos. In other words, everything in nature exists to fulfil a goal.

EXPLAINING things in terms of their purposes was not unusual among classical Greek philosophers, but today it stands at odds with our modern, scientific understanding of the world. To our modern eyes it is quite normal to describe a man-made object, such as a tool, in terms of its function or purpose. A hammer, for example, exists for the purpose of pounding in nails. But this is an extrinsic purpose, one that is imposed upon it from the outside. What Aristotle proposed was that everything, including everything in the natural world, has an intrinsic purpose: that is, each thing exists in order to achieve its own ends – its internal purpose. For example, a seed’s purpose is to germinate and become a plant, and trees exist in order to produce fruit.

For Aristotle, it is not only living things that exist for a purpose. Rain falls in order to moisten the ground and enable plants to grow. It is the rain’s telos to water the earth, and the plants’ telos to grow. Their purpose or goal is the reason they have come into being.

More in line with our modern thinking is the Atomists’ assertion that natural things do not have an intrinsic purpose or “final cause”: instead, their existence is the cause of other things. Rain does not fall in order to water the plants; rather, the plants use the moisture that happens to have been provided by the rainfall.

. The Unfolding World

For Aristotle, the essential property of a seed is its ability to grow. That is also its intrinsic purpose: it exists to become a plant, which, in turn, exists in order to produce seeds. Living things are therefore characterised by their tendency to move or change, and to reproduce. And, since all terrestrial things are imperfect and impermanent, beings not only grow, but also eventually perish and decay.

. Causation

Aristotle’s theory of causation is based on his idea that everything has four causes. What we usually think of as a cause – that which makes a thing happen – is what Aristotle calls an “efficient cause”. For example, a person who pushes a rock downhill is the efficient cause of the rock’s movement. The purpose, or “final cause”, of its movement – why it goes downwards instead of up or sideways – is that it is seeking the centre of the Earth. The final cause of the action of pushing the rock is to see how far it will roll. The rock’s movement is also determined by formal and material causes.

Efficient Cause – in this example, the efficient cause is the person who pushes the rock. The rock moves because of the person’s actions.

Material Cause – This is the rock’s physical composition. The rock is made of earth, and so, because earthy things seek the centre of the Earth, it moves downwards.

Formal Cause – The shape of the rock’s trajectory is determined by the landscape. The rock’s rolling and bouncing are caused by the slopes and bumps of the hill.

Final Cause – The rock comes to rest when it reaches the closest it can get to the centre of the Earth – the bottom of the hill.

THE UNMOVED MOVER

Aristotle’s universe had no beginning, but he believed that something must have set the heavenly bodies in motion, since everything is caused by something else. However, this raises two questions: What caused that cause, and what moved the mover of the Universe? Aristotle proposed the idea of a first cause, an “unmoved mover”, responsible for all the motion in the universe.

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Arts, Philosophy

Philosophy: Plato’s allegory of the cave

UNDERSTANDING PLATO

Intro: In the Republic, Plato presented an allegory to show how our knowledge of reality is restricted by the deceptive information provided by our senses

A world of shadows

PLATO asks us to imagine a cave in which some prisoners are held captive. They are shackled to face the back wall of the cave and are unable to turn their heads. Their field of view is restricted to the wall in front of them, across which they can see images moving.

The captives are unaware that behind them, hidden by a low wall, another group of people are parading a variety of objects in front of a fire. It is the shadows of these objects that the prisoners can see in front of them. Because all the prisoners can see are the shadows, this is the only reality of which they are aware. They know nothing of the objects casting the shadows, and would not believe it if they were told about them. They are literally being kept in the dark about the true nature of the world that they inhabit.

The point that Plato is making is that our own perception of the world is similarly restricted, and that the things we believe to be real are merely “shadows” of the things that exist in the ideal realm of the Forms.

Platonic realms

At the heart of Plato’s philosophy is the notion that the world we live in is deceptive, and that our senses cannot be trusted. For Plato, our world is merely a shadow cast by a higher realm of the Forms.

A world of Forms

Plato, like many philosophers before and since, was an accomplished mathematician, and was fascinated by geometry. He observed that there are many instances of things that are, for example, circular in the world about us, and that we recognise them as instances of a circle. We can do this, he argued, because we have an idea in our minds of what a circle is – what he called the “Idea” or “Form” of a circle – and unlike the particular instances of circular things, this Form is an ideal circle, with no imperfections. Indeed, everything we experience – from horses to acts of justice – are particular things that we recognise by comparing them with their relative Forms in our minds.

What is more, Plato claimed that since we cannot perceive these Forms, they must exist in a realm beyond our senses – one that we recognise with our psyche, or intellect. This process of recognition is largely instinctual, but Plato argued that philosophers are needed to comprehend certain Forms. In Plato’s dualistic universe, the two world’s he describes are perceived in different ways. The earthly realm is experienced by our bodily senses; the ideal realm being understood by the mind or intellect. This is what the concept of Dualism means. In practice, this is why philosophers should be used to organise society and advise on ethical matters, a key tenet that runs throughout Plato’s philosophy.

Innate Knowledge

Plato believed that our knowledge of the Forms is something we are born with, not something we acquire through experience. Rather, we use our reason to access the Forms, in whose realm we lived before we were born. For Plato, philosophers are like midwives: their role is to bring to light what we innately already know.

ONE WORLD ONLY

Plato’s most brilliant student, Aristotle, did not agree with his mentor’s theory of Forms. Instead, he proposed that we learn about the world through experience alone.

Empiricism

Aristotle could not accept the idea of a separate world of ideal Forms. Plato had argued that the Forms – the qualities of being circular, good, or just, for instance – exist in a separate realm. Aristotle believed that there is only one cosmos, which we learn about through our experience of it. Although he accepted that “universal” qualities (such as redness) exist, he did not believe that they do so in a separate dimension. Rather, he said, they exist in each particular instance in this world.

For example, the idea of a “circle” is general: we have in our minds an idea of what constitutes a perfect circle. He explains that this is not because we have innate knowledge of the perfect (Form of a) circle, but because we experience circular things, and then generalise about them, having seen what they have in common.

For Aristotle, we gather information about the world through our senses and make sense of it by using our intellect or reason. In this way we build up ideas, apply labels to them, and make distinctions. As a philosophical stance, this is known as “empiricism”, as opposed to Plato’s “rationalism”.

Essential and Accidental Properties

Aristotle argued that all things have two kinds of properties. An essential property is what makes a thing what it is. Its other properties are “accidental” properties.

. An apple’s accidental properties include its colour, shape, and weight. It is an apple whether it is green or red, round or oval, large or small

. The apple’s essential property is the substance that it is made from

. The essential property of a ball, however, is its shape; the substance it is made of is an accidental property

NEED TO KNOW

> Epistemology is the branch of philosophy concerned with knowledge and the way in which we acquire it.

> Inductive reasoning is the logical process of making a general rule from a number of particular instances.

> Empirical knowledge is knowledge that is acquired by observation or experience rather than through reasoning.

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