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.

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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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Increased testing does not explain the increase in US COVID cases

The Logic of Science

The US is experiencing another sharp increase in COVID19 cases. This is a simple fact, but as always seems to be the case in today’s world, this fact is being treated as an opinion. Countless people (including prominent politicians and even the president) are claiming that cases are not actually increasing, and the apparent increase is simply the result of increased testing. This claim is dangerous and untrue, but it also offers a good opportunity to teach some lessons in data analysis. Obviously, an increase in testing will result in an increase in the number of cases that are documented, that much is true, but that doesn’t necessarily mean that the entirety of the increase is from increased testing. So how can we tell whether the true number of cases is increasing? There are multiple ways to examine this, and I’m going to walk through several of them and try…

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Trump retweets a video of deplorables calling for white power

Why Evolution Is True

This morning I retweeted Trump’s own retweeted video of people in Florida yelling at each other, with one screaming “white power” several times, but that tweet been quickly removed by the Prez or his minons:

But you can still see the original on the Rolling Stone site, and I’ve put a version below the screenshot:

The Bad Tweet passed on by tRump. The seniors in their golf carts are feisty (and badly deluded), but there’s also pushback.

From Rolling Stone:

On Sunday morning, the president of the United States once again showed his racist leanings by retweeting a video of one of his supporters chanting “white power.”

“Thank you to the great people of The Villages. The Radical Left Do Nothing Democrats will Fall in the Fall. Corrupt Joe…

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The eclipse photo that made Einstein famous

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Arrival and Departure by Arthur Koestler (1943)

Books & Boots

Warning: This review contains references to rape, torture and the Nazi murder of Jews.

Arthur Koestler, a potted biography

Arthur Koestler was born to a Jewish mother in Budapest, capital of the Hungarian part of the the Austro-Hungarian Empire, in 1905. So he was 14 when the short-lived Hungarian communist government of Bela Kun seized power in 1919 and Koestler later remembered his teenage high hopes for it and for a better future. The Bela Kun regime was crushed and replaced by the authoritarian rule of Admiral Horthy, but Koestler retained that youthful idealism

Koestler became a journalist and travelled widely in the late 1920s and early 1930s, reporting from the Soviet Union, Palestine and Germany, for a variety of German newspapers. He joined the German Communist Party in 1931.

In 1936, early in the Spanish Civil War, Koestler got access, as an accredited journalist, to General Franco’s headquarters and…

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June 25, 1900: Birth of Lord Louis Mountbatten, 1st Earl Mountbatten of Burma. Part I.

European Royal History

Admiral of the Fleet Louis Francis Albert Victor Nicholas Mountbatten, 1st Earl Mountbatten of Burma (born Prince Louis of Battenberg; June 25, 1900 – August 27, 1979), was a British Royal Navy officer and statesman, a Maternal Uncle of Prince Philip, Duke of Edinburgh, and second cousin once removed of Queen Elizabeth II of the United Kingdom. During the Second World War, he was Supreme Allied Commander, South East Asia Command (1943–1946). He was the last Viceroy of India (1947) and the first governor-general of independent India (1947–1948).

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Lord Louis Mountbatten, 1st Earl Mountbatten of Burma

Lord Mountbatten was known as His Serene Highness Prince Louis of Battenberg from the time of his birth at Frogmore House in the Home Park, Windsor, Berkshire until 1917, when he and several other relations of King George V of the United Kingdom dropped their German styles and titles.

Lord Mountbatten was the youngest child…

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Homage to Catalonia by George Orwell (1938)

Books & Boots

Potted biography

Orwell was born Eric Arthur Blair to a civil servant in India in 1903. The family moved back to England in 1907 and sent young Eric, first to prep school near Eastbourne, then to Eton, where he met other boys who were to be among the literary luminaries of his generation. In other words he was brought up to be the toffiest of the toffs. However, unlike most of his literary contemporaries, Eric decided not to go on to Oxford or Cambridge but instead enlisted in the Indian Imperial Police and returned to Burma. Here he served from 1922 until 1927, wielding great responsibility for large provinces and huge numbers of ‘natives’.

Slowly he lost his faith in the Imperial mission, and came to dislike his role. One contemporary said he had an unusual sympathy for the natives and went to the unprecedented lengths of learning their language…

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Laughter is the best medicine

Paddy’s Pontifications

When in Cambridge in 1961 I saw a current British Prime Minister portrayed on stage for the first time in “Beyond the Fringe” I’m not sure that I was aware of the significance of the moment. Later I bought the early copies of “Private Eye” in the streets of the City. And before I left school Ned Sherrin and David Frost had launched the groundbreaking “That Was The Week That Was”. What was happening was Satire.

Beyond the Fringe

The world is absurd, and people lie and cheat. Politicians parody themselves daily and people have prejudices out of ignorance or venality. What satire did was to hold a mirror up to all this – sometimes the mirror enlarged and sometimes it distorted but it always reflected and allowed the viewer or the reader to judge.

Peter Cook, Dudley Moore, Jonathan Miller, Alan Bennett, David Frost, Barry Humphries, Richard Ingrams and…

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Poetry of the Thirties edited by Robin Skelton (1964)

Books & Boots

Even before they were quite over, the Thirties took on the appearance of myth… It is rare for a decade to be so self-conscious… (Robin Skelton in his introduction)

Robin Skelton (October 1925 – August 1997) was a British-born academic, writer, poet, and anthologist. In 1963 he emigrated to Canada and taught at universities there. He appears to have written an astonishing 62 books of verse (some of them explanations of theory & metre), five novels, 15 non-fiction books and some 23 anthologies.

This Penguin paperback edition of poetry from the 1930s is similarly profuse. It contains some 169 poems by no fewer than 43 poets, a very wide-ranging selection.

Some are super-famous – W.H. Auden, Dylan Thomas, John Betjeman.

Some more niche, like the Surrealist poets David Gascoyne, Hugh Sykes Davies and Philip O’Connor.

Some wrote little but have cult followings, like the fierce young communist John Cornford…

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Mystery of how Earth barely escaped an atomic bomb-scale mega meteor

Tallbloke's Talkshop

Credit: Wikipedia
Time for another Tunguska meteor theory.
– – –
When a meteor zooms toward Earth at 45,000 mph with the strength 10-15 megatons of TNT—185 times more energy than the Hiroshima atomic bomb—it could possibly take out the entire planet, says Syfy.

If something like that doesn’t scream total annihilation, it’s hard to say what does, except this time it just missed.

Scorched earth and flattened trees were all that was left of the mysterious object after it passed dangerously close to the Tunguska region of Siberia in 1908.

Theories have ranged from a black hole colliding with Earth to a clash of matter and antimatter to an alien spaceship crash-landing. An eyewitness even swore the sky was being ripped in two. But why no crater? No debris?

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The Pianist: The Extraordinary Story of One Man’s Survival in Warsaw 1939–45 by Władysław Szpilman

Books & Boots

At the edge of the compound, where one of the streets ran into it, there was an unoccupied space. Everyone was giving this spot a wide berth, never lingering there but casting glances of horror at it. Bodies lay there: the bodies of those killed yesterday for some crime or other, perhaps even for attempting to escape. Among the bodies of men were the corpses of a young woman and two girls with their skulls smashed to pieces. The wall under which the bodies lay showed clear traces of bloodstains and brain tissue. The children had been murdered by a favourite German method: seized by the legs, their heads swung violently against the wall. Large black flies were walking over the dead and the pools of spilt blood on the ground, and the bodies were almost visibly bloating and decaying in the heat. (The Pianist, page 99)

Władysław…

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