Category Archives: Science

Arts, Philosophy, Science

Philosophy: Facts and ideas

REASON AND EXPERIENCE

Intro: Like John Locke before him, David Hume believed that our knowledge derives primarily from experience. However, he also argued that we can never know anything about the world with certainty

Natural assumptions

David Hume (1711–1776) was primarily interested in epistemology (the nature of knowledge), rather than metaphysics (the nature of the universe). In An Enquiry Concerning Human Understanding, he set out to examine the way that human psychology determines what we can and cannot know, and in particular what we can and cannot know for certain.

Although an empiricist – that is, he believed that experience is our primary source of knowledge – Hume conceded that many propositions, such as mathematical axioms, can be arrived at by reason alone and cannot be doubted: to doubt that 2+2=4 is to fail to understand its meaning. However, he argued that such truths tell us nothing about the world: they simply express relationships between ideas. To gain knowledge about the world we need experience, but Hume argues that such knowledge can never be certain. We are therefore caught on the prongs of a fork: on the one hand, we have certainty about things that tell us nothing about the world; on the other hand, our knowledge about the world is never certain.

Hume argues that it is human nature to make assumptions about the world, especially that it is predictable and uniform. We assume, for example, that when a brick is thrown at a window the brick “causes” the window to smash. However, Hume argues that all we know for certain is that throwing a brick at a window is regularly followed by the window smashing. We never perceive causes, he says, but only a “constant conjunction” of events – that is, the regular occurrence of certain events following others. We only imagine a “link” between them.

Hume is not saying we are wrong to make assumptions – life would be impossible without them. Rather, he is suggesting that we should recognise the extent to which assumptions govern our lives, and not confuse them with the truth.

Relations of ideas

Statements of this kind are necessary truths, which means that they cannot be contradicted logically. For example, it is not possible to say that the angles of a triangle do not add up to 180 degrees, or that 2 plus 2 does not equal 4. We can be certain of such truths, but they tell us nothing about the world: they merely express relationships between ideas.

Hume’s fork

For Hume, there are two kinds of truth: “relations of ideas” and “matters of fact”. The former are true by definition, while the latter depend on the facts. Philosophers call this distinction “Hume’s fork”.

Matters of fact

Statements of this kind are contingent, which means that their truth or falsehood depend on whether or not they represent the facts. For example, it is not illogical to deny the statements “It is snowing” or “I have a cat”. Their truth depends simply on the current state of the weather and whether I own a cat or not.

“Custom, then, is the great guide of human life.” – David Hume, An Enquiry Concerning Human Understanding (1748)

THE PROBLEM OF INDUCTION

Hume argued that general statements such as “The Sun rises in the east” are logically unjustified because we cannot prove that the Sun will not rise in the west tomorrow. This also means that scientific claims, such as “The Moon orbits the Earth”, are unjustified because we may discover, for example, that the Moon may also behave in a different way tomorrow. Such statements are known as “inductions”, because they use the inductive method of reasoning – that is, they make general claims based on a limited number of particular cases or events. There are different types of inductive argument which will be examined in detail in a future entry.

NEED TO KNOW

. According to Hume, the difference between mathematics and the natural sciences is that mathematical truths are what he calls “relations or ideas”, or necessary truths, whereas scientific truths are contingent, or conditional, “matters of fact”.

. Half a century before Hume, Gottfried Leibniz made a similar distinction between truths of reasoning and truths of fact. Leibniz was an accomplished mathematician. He invented calculus (which Isaac Newton was also instrumental in) and was characterised as an optimistic philosopher. He believed that God is supremely perfect, and that ours is the best possible world – one in which the modern “monads” exist in harmony. The word “monad” is derived from the Greek word monas, meaning “unit”, which Leibniz borrowed to describe the fundamental units of existence. He distinguished “truths of reasoning” from “truths of fact”.

. Immanuel Kant and later philosophers distinguished between analytic statements, whose truth can be established by reasoning alone, and synthetic statements, which are verified by reference to the facts.

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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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Psychology, Research, Science

Are male and female brains wired differently? 

GENDER BRAINS

Intro: It is often pointed where we differ, but when it comes to our brains, research shows that there are far more similarities than differences

WE are told that men and women are so different, it’s as if they came from separate planets. Martian men are stereotypically target-focused, assertive, and good at navigating; women born on Venus are more empathetic, caring, and expert multitaskers. We are all fascinated by what makes the other sex tick, but back on Earth, when it comes to brains, much of what’s been written about the sex divide is more science fiction than scientific fact.

Websites and news outlets have seeped scientific-sounding theories into common wisdom, such as the idea that women listen with both sides of their brain, whereas men use only one side; or that men and women navigate using “entirely different” brain regions. Some even claim that there is a “male brain” and a “female brain”.

These ideas often have their roots in scientific research, but much of it is based on early experiments in our brains which were either found later to be insignificant, or their results were misinterpreted or misreported.

Scientists are suckers for wanting to tell a story that will be the talk of the town – and the media are willing accomplices. Less headline-grabbing experiments that show little or no difference can get stuffed in the drawer, never to see the light of day.

So, what does the science really say? From the eighth week in the womb, little boys’ and girls’ brains do start to develop slightly differently. Throughout our lives, the sex hormones testosterone, oestrogen, and progesterone mould our individual physical and emotional development. Hormone level differences tweak the dial on characteristics such as aggression, pain threshold, stress response, and parent-child bonding, but each person is so unique that there is often more variation within each sex than there is between them.

Male and female brains don’t differ significantly in size, either. Men’s brains are slightly larger as a consequence of their larger bodies, and thanks to detailed scanning we know that some brain parts differ in proportion between the sexes, but the differences are too small to claim that there is such a thing as a “male brain” or a “female brain”.

Most areas of mental functioning, behaviour and personality are the same in both sexes. What differences there are, such as in aggression levels, are usually driven by the differences in sex hormones such as testosterone after puberty.

Nature or nurture?

Recent research points to the historic sex divide actually being down to society, not science. When the magnifying glass of science reveals the workings of the brain, the accepted male and female stereotypes mostly vanish.

Some scientists now think that what differences there are between male and female brains – such as, say, in map reading – are the result not of biology, but of thousands of years of brain-training. The good news, however, is the brain is brilliant at learning new things – you can adapt and learn many new skills within a lifetime.

So it is logical that, if given the opportunity, men and women can learn skills stereotypical of the other sex very easily. For example, children who are given Lego to play with are likely to mature and have brains which have larger spatial cortexes, regardless of whether they are male or female.

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