Introduction

Welcome to Tim Harding’s blog of writings and talks about logic, rationality, philosophy and skepticism. There are also some reblogs of some of Tim’s favourite posts by other writers, plus some of his favourite quotations and videos This blog has a Facebook connection at The Logical Place.

There are over 2,300 posts here about all sorts of topics – please have a good look around before leaving.

If you are looking for an article about Skepticism, Science and Scientism published in The Skeptic magazine titled ”A Step Too Far?’, it is available here.

If you are looking for an article about the Birth of Experimental Science published in The Skeptic magazine titled ‘Out of the Dark’, it is available here.

If you are looking for an article about the Dark Ages published in The Skeptic magazine titled ‘In the Dark’, it is available here.

If you are looking for an article about the Traditional Chinese Medicine vs. Endangered Species published in The Skeptic magazine titled ‘Bad Medicine’, it is available here.

If you are looking for an article about the rejection of expertise published in The Skeptic magazine titled ‘Who needs to Know?’, it is available here.

If you are looking for an article about Charles Darwin published in The Skeptic magazine titled ‘Darwin’s Missing Link“, it is available here.

If you are looking for an article about the Astronomical Renaissance published in The Skeptic magazine titled ‘Rebirth of the Universe‘, it is available here.

If you are looking for an article about DNA and GM foods published in The Skeptic magazine titled ‘The Good Oil‘, it is available here.

If you are looking for an article about animal welfare published in The Skeptic magazine titled ‘Creature Features‘, it is available here.

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What is logic?

The word ‘logic‘ is not easy to define, because it has slightly different meanings in various applications ranging from philosophy, to mathematics to computer science. In philosophy, logic’s main concern is with the validity or cogency of arguments. The essential difference between informal logic and formal logic is that informal logic uses natural language, whereas formal logic (also known as symbolic logic) is more complex and uses mathematical symbols to overcome the frequent ambiguity or imprecision of natural language.

So what is an argument? In everyday life, we use the word ‘argument’ to mean a verbal dispute or disagreement (which is actually a clash between two or more arguments put forward by different people). This is not the way this word is usually used in philosophical logic, where arguments are those statements a person makes in the attempt to convince someone of something, or present reasons for accepting a given conclusion. In this sense, an argument consist of statements or propositions, called its premises, from which a conclusion is claimed to follow (in the case of a deductive argument) or be inferred (in the case of an inductive argument). Deductive conclusions usually begin with a word like ‘therefore’, ‘thus’, ‘so’ or ‘it follows that’.

A good argument is one that has two virtues: good form and all true premises. Arguments can be either deductiveinductive  or abductive. A deductive argument with valid form and true premises is said to be sound. An inductive argument based on strong evidence is said to be cogent. The term ‘good argument’ covers all three of these types of arguments.

Deductive arguments

A valid argument is a deductive argument where the conclusion necessarily follows from the premises, because of the logical structure of the argument. That is, if the premises are true, then the conclusion must also be true. Conversely, an invalid argument is one where the conclusion does not logically follow from the premises. However, the validity or invalidity of arguments must be clearly distinguished from the truth or falsity of its premises. It is possible for the conclusion of a valid argument to be true, even though one or more of its premises are false. For example, consider the following argument:

Premise 1: Napoleon was German
Premise 2: All Germans are Europeans
Conclusion: Therefore, Napoleon was European

The conclusion that Napoleon was European is true, even though Premise 1 is false. This argument is valid because of its logical structure, not because its premises and conclusion are all true (which they are not). Even if the premises and conclusion were all true, it wouldn’t necessarily mean that the argument was valid. If an argument has true premises and its form is valid, then its conclusion must be true.

Deductive logic is essentially about consistency. The rules of logic are not arbitrary, like the rules for a game of chess. They exist to avoid internal contradictions within an argument. For example, if we have an argument with the following premises:

Premise 1: Napoleon was either German or French
Premise 2: Napoleon was not German

The conclusion cannot logically be “Therefore, Napoleon was German” because that would directly contradict Premise 2. So the logical conclusion can only be: “Therefore, Napoleon was French”, not because we know that it happens to be true, but because it is the only possible conclusion if both the premises are true. This is admittedly a simple and self-evident example, but similar reasoning applies to more complex arguments where the rules of logic are not so self-evident. In summary, the rules of logic exist because breaking the rules would entail internal contradictions within the argument.

Inductive arguments

An inductive argument is one where the premises seek to supply strong evidence for (not absolute proof of) the truth of the conclusion. While the conclusion of a sound deductive argument is supposed to be certain, the conclusion of a cogent inductive argument is supposed to be probable, based upon the evidence given. An example of an inductive argument is: 

Premise 1: Almost all people are taller than 26 inches
Premise 2: George is a person
Conclusion: Therefore, George is almost certainly taller than 26 inches

Whilst an inductive argument based on strong evidence can be cogent, there is some dispute amongst philosophers as to the reliability of induction as a scientific method. For example, by the problem of induction, no number of confirming observations can verify a universal generalization, such as ‘All swans are white’, yet it is logically possible to falsify it by observing a single black swan.

Abductive arguments

Abduction may be described as an “inference to the best explanation”, and whilst not as reliable as deduction or induction, it can still be a useful form of reasoning. For example, a typical abductive reasoning process used by doctors in diagnosis might be: “this set of symptoms could be caused by illnesses X, Y or Z. If I ask some more questions or conduct some tests I can rule out X and Y, so it must be Z.

Incidentally, the doctor is the one who is doing the abduction here, not the patient. By accepting the doctor’s diagnosis, the patient is using inductive reasoning that the doctor has a sufficiently high probability of being right that it is rational to accept the diagnosis. This is actually an acceptable form of the Argument from Authority (only the deductive form is fallacious).

References:

Hodges, W. (1977) Logic – an introduction to elementary logic (2nd ed. 2001) Penguin, London.
Lemmon, E.J. (1987) Beginning Logic. Hackett Publishing Company, Indianapolis.

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Reasoning

Rationality may be defined as as the quality of being consistent with or using reason, which is further defined as the mental ability to draw inferences or conclusions from premises (the ‘if – then’ connection). The application of reason is known as reasoning; the main categories of which are deductive and inductive reasoning. A deductive argument with valid form and true premises is said to be sound. An inductive argument based on strong evidence is said to be cogent. It is rational to accept the conclusions of arguments that are sound or cogent, unless and until they are effectively refuted.

A fallacy is an error of reasoning resulting in a misconception or false conclusion. A fallacious argument can be deductively invalid or one that has insufficient inductive strength. A deductively invalid argument is one where the conclusion does not logically follow from the premises. That is , the conclusion can be false even if the premises are true. An example of an inductively invalid argument is a conclusion that smoking does not cause cancer based on the anecdotal evidence of only one healthy smoker.

By accident or design, fallacies may exploit emotional triggers in the listener (e.g. appeal to emotion), or take advantage of social relationships between people (e.g. argument from authority). By definition, a belief arising from a logical fallacy is contrary to reason and is therefore irrational, even though a small number of such beliefs might possibly be true by coincidence.

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Is “white empiricism” hindering physics?

Why Evolution Is True

My ears always perk up when I hear the claim that there are special ways of doing science (“ways of knowing” if you will), that are practiced by different groups, and that the nature of science would be different, and better, if these groups are included in science.  There is a modicum of truth in this. Nobody denies that, in the past, oppressed people—women, minorities, and so on—have not been given the same opportunities to enter science as, say, white men. And I can think of at least one case in which the interests of different groups, by being different, have enriched science. (I think that the presence of women in evolutionary biology, for example, could have prompted the increasing emphasis on female choice in “Darwinian” sexual selection, though of course males have also done pioneering work in that area and my contention is aguable.)

But in general, though social…

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Into the Night: Cabarets and Clubs in Modern Art @ Barbican

Books & Boots

This is a fabulous exhibition, packed with wonderful paintings, photos, films, drawings, posters and all kinds of memorabilia connected with a dozen or so avant-garde and trend-setting nightclubs around the world from the 1880s to the 1960s, And as well as all the lovely works and ideas and stories, it raises a number of questions, which I’ll address at the end of this review…

First the clubs and their stories. The Barbican exhibition space is laid out not as ‘rooms’ but as successive alcoves or spaces running off the first floor gallery, from which you look down onto the ground floor which can be divided up into various areas, or opened up to make one through-space (as they did for the Lee Krasner exhibition).

There are eight of these room-sized alcoves upstairs, and in this exhibition each one tells the story of one or two famous nightclubs which became a focus…

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The Quiet Revolution, Boyer lectures 2012, by Marcia Langton

ANZ LitLovers LitBlog

Every year, ABC Radio invites a public intellectual to give a series of lectures. Inaugurated in 1959 as ABC Lectures, they were renamed as the Boyer Lectures in 1961 as a memorial to Sir Richard Boyer, who as chairman of the ABC had led their introduction.  (You can see past programs and still listen to some of them, here.)

In 2012, Professor Marcia Langton, a descendant of the Yiman and Bidjara people of Queensland, introduced the 53rd series of lectures with a statement that is probably still true today:

The emergence of an Aboriginal middle class in Australia in the last two to three decades has gone largely unnoticed. (p.31)

While she acknowledges that the numbers are small, they portend  an economic future for Aboriginal people unimaginable fifty years ago. Langton herself, she tells us later in the lectures, was born at a time when Indigenous people weren’t…

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John Opie @ Tate Britain

Books & Boots

Tate Britain is labyrinthine enough to have half a dozen side rooms and spaces where it mounts small (and sometimes not so small) ‘spotlight’ exhibitions, focusing on a particular topic or artist.

In a modest room off the main atrium, little more than a glorified corridor, Tate Britain is hosting a small but beautifully formed exhibition about the painting and cultural environment of the late-eighteenth century English painter, John Opie (1761 – 1807).

The Cornish Wonder

Opie’s success is surprising because of his background. In the late eighteenth century artists generally came from artistic families, or from educated, middle-class homes where their interest in such a risky career could be indulged.

In contrast, Opie was born at St Agnes, near Truro in Cornwall, the son of a mine carpenter. Although he did attend school, he was probably largely self-educated. A wealthy local couple later reported that he visited the library in…

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John Cleese: Political Correctness Can Lead to an Orwellian Nightmare

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Words and phrases I hate

Why Evolution Is True

All our excursions and landings in Antarctica for the day have been cancelled because of very high winds (ca. 50 mph) and very low temperatures. Even a few minutes on deck without gloves or a hat will freeze your extremities. The sea is covered with bits of ice, large and small, and I’m not lecturing today.

So what’s there to do except engage in a favorite way of blowing off steam: noting the words and phrases I hate? Today I have three, but two come from the most reliable source of bad language: HuffPost. The other is a new phrase that grates on me most painfully.

I can’t guarantee that I haven’t mentioned any of these before.

1.) “Fierce”. This is now used not to denote fearless aggressiveness, but simply “something admirable”, as in the HuffPost article below (click on screenshot). By eviscerating the word’s meaning, its users show a…

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Ohio House passes bill apparently allowing students to give wrong answers if those answers are based on religious conviction

I’m speechless.

Why Evolution Is True

Here we go again. It’s fairly normal procedure for evolutionary biologists to tell their creationist students that they don’t have to accept the evolution they’re taught in class, but they must at least regurgitate the correct answers on exams. But the House part of the Ohio state legislature has apparently gone further—they’ve passed a bill mandating that students cannot be penalized (or rewarded) for giving answers on tests or assignments that comport with their religion.

Read this report at Cleveland.com (click on screenshot):

From the site:

The Ohio House sent to the Senate on Wednesday a measure that would prohibit public schools from penalizing students for some work that contains religious beliefs.

Critics have called the bill unnecessary or valuing religion over secularism. One critic said under the bill, if a student turned in homework saying the earth is 10,000 years old – a belief held by some creationists —…

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After Tamerlane: The Rise and Fall of Global Empires 1400 – 2000 by John Darwin (2007)

Books & Boots

Empires exist to accumulate power on an extensive scale…
(After Tamerlane: The Rise and Fall of Global Empires 1400 – 2000 page 483)

Why did the nations of Western Europe rise through the 18th and 19th centuries to create empires which stretched around the world, how did they manage to subjugate ancient nations like China and Japan, to turn vast India into a colonial possession, to carve up Africa between them?

How did white European cultures come to dominate not only the territories and peoples who they colonised, but to create the modern mindset – a vast mental framework which encompasses capitalist economics, science and technology and engineering, which dominates the world right down to the present day?

Why did the maritime states of Europe (Britain, France, the Dutch, Spanish and Portuguese) end up either settling from scratch the relatively empty places of the world (America, Australia), or bringing…

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Inspired by the east: how the Islamic world influenced western art @ the British Museum

Books & Boots

European explorers

As John Darwin’s brilliant history of Eurasian empires, After Tamerlane, makes clear, quite a few things distinguished European culture from the culture of the other Eurasian empires (i.e. the Ottoman Empire, the Safavid Empire in Persia, the Moghul Empire in northern India, the Chinese Empire and the Japanese Empire) in the centuries after the death of Tamerlane the Great in 1405.

Just two of them were a readiness to travel and explore, and an endless curiosity which led to almost obsessive collecting and categorising and curating and exhibiting.

No Chinese explorers visited Europe during the 19th century and were so dazzled by its history and architecture and art that they made copious sketches and drawings, took photographs, bought up every quaint European curio they could get their hands on, and carried them all back to China to trigger an artistic renaissance.

That kind of thing just didn’t…

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Sir Stamford Raffles: collecting in Southeast Asia 1811-1824 @ the British Museum

Books & Boots

As it is in just one room upstairs at the back of the British Museum, and is FREE, I thought this would be a relatively light and small exhibition to enjoy, but I was wrong. It’s a surprisingly packed exhibition which gives a panoramic view of Indonesian, and particularly Javanese, culture – at least through the eyes of one of its earliest European collectors.

Puppet of the comic character Sabda Palon, one of Damarwulan’s servants (Central Java, probably Surakarta, 1700s) © Trustees of the British Museum

Stamford Raffles, a potted biography

Sir Thomas Stamford Raffles (1781 – 1826) started working for the East India Company when he was 14, and spent most of his life as an East India Company official in Southeast Asia. In 1811 he was appointed Lieutenant-Governor of Java when the British seized it from the Dutch, but in 1815, when we gave it back to the…

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