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 1500 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 recently 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 recently 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 recently 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 recently 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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Well said

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Clarifying Sam Harris’ clarifications

Scientia Salon

Embedding_Ethics_in_Engineering_Education-heroby Dwayne Holmes

[Editor’s note: this essay is an expansion and follow up to the author’s submission to the contest organized by Sam Harris for the best criticism of his arguments on science and ethics, as laid out in The Moral Landscape.]

The semantics of “science” is important

In responding to Ryan Born’s essay [1] — which won the competition giving readers a chance to challenge the arguments Sam Harris made for merging science and ethics in his book The Moral Landscape (henceforth, TML) — Harris undermined most of the discussion concerning the “scientific” nature of his theory with this statement:

“The whole point of The Moral Landscape was to argue for the existence of moral truths … every bit as real as the truths of physics. If readers want to concede that point without calling the acquisition of such truths a “science,” that’s a semantic choice that has no…

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Bauhaus by Frank Whitford (1984)

Books & Boots

It is perhaps details of the more trivial aspects of life which help us more clearly to imagine the atmosphere of the Bauhaus. (p.162)

This is a shit-hot book. I’ve read plenty of accounts of the Bauhaus which emphasise its seismic importance to later design and architecture, but this is the only one which really brings it alive and makes it human. It is almost as gripping, and certainly filled with as many vivid characters and funny anecdotes, as a good novel.

Whitford’s book really emphasises that the Bauhaus was not some mythical source of everything wonderful in 20th century design, but a college of art and design, in essence like many others of the day, staffed by a pretty eccentric bunch of teachers and the usual scruffy, lazy and sometimes brilliant students. During its very chequered fifteen year history it faced all the usual, mundane problems of funding, staffing…

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Corruption and Parking Tickets

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A new blood test can detect eight different cancers in their early stages

The Conversation

File 20180117 53310 9zjg6j.jpg?ixlib=rb 1.1
A liquid biopsy is far less invasive than a standard biopsy, where a needle is put into a solid tumour to confirm a cancer diagnosis. From shutterstock.com

Peter Gibbs, Walter and Eliza Hall Institute

Researchers have developed a blood test that can detect the presence of eight common cancers. Called CancerSEEK, the blood test detects tiny amounts of DNA and proteins released into the blood stream from cancer cells. This can then indicate the presence of ovarian, liver, stomach, pancreatic, oesophageal, bowel, lung or breast cancers.

Known as a liquid biopsy, the test is distinctly different to a standard biopsy, where a needle is put into a solid tumour to confirm a cancer diagnosis. CancerSEEK, is also far less invasive. It can be performed without even knowing a cancer is present, and therefore allow for early diagnosis and more chance of a cure.


Read more:
Interactive body map: what really gives you cancer?


The test has been shown to reliably detect early stage and curable cancers. It has also been found to rarely be positive in people who don’t have cancer. This prevents significant anxiety and further invasive tests for those who don’t need them.

Several cancers can be screened for at once, and the test can be performed at the same time as routine blood tests, such as a cholesterol check. But the test is still some years away from being used in the clinic.

How the test works

Often long before causing any symptoms, even very small tumours will begin to release minute amounts of mutated DNA and abnormal proteins into blood. While DNA and proteins are also released from normal cells, the DNA and proteins from cancer cells are unique, containing multiple changes not present in normal cells.

The newly developed blood-based cancer DNA test is exquisitely sensitive, accurately detecting one mutated fragment of DNA among 10,000 normal DNA fragments, literally “finding the needle in the haystack”.

Tumours release mutated DNA and abnormal proteins into blood. From shutterstock.com

We used CancerSEEK in just over 1,000 people with different types of early stage cancers. It was shown to accurately detect the cancer, including in 70% or more of pancreas, ovary, liver, stomach and esophageal cancers. For each of these tumour types there are currently no screening tests available – blood based or otherwise.

Along with cancer detection, the blood test accurately predicted what type of cancer it was in 83% of cases.

Published in the journal Science, the research was led by a team from John Hopkins University, with collaboration from Australian scientists at the Walter and Eliza Hall Institute.

Why it’s important

Steady progress continues to be made in the treatment of advanced cancers, including major gains in life expectancy. But this can come at significant physical and financial cost. Early diagnosis remains the key to avoiding the potentially devastating impact of many cancer treatments and to reducing cancer deaths.

However, where there are proven screening tests that lead to earlier diagnosis and better outcomes, such as colonoscopy screening for bowel cancer, these are typically unpleasant. They also have associated risks, only screen for one cancer at a time and population uptake is often poor. And for many major tumour types there are currently no effective screening tests.


Read more:
Can we use a simple blood test to detect cancer?


There are characteristic patterns of mutations and altered proteins that differ among cancer types. So CancerSEEK can not only detect that there is a cancer somewhere in the body but can also suggest where to start looking.

For example, if the pattern suggests a bowel cancer, then a colonoscopy is a logical next step. When blood samples were taken from over 800 apparently healthy controls, less than 1% scored a positive test. This means the test is rarely positive for people who don’t have cancer, thereby reducing the problem of overdiagnosis.

Overall, these results appear to be in stark contrast to previously developed blood-based tests for cancer screening. Currently the only widely used one of is the prostate specific antigen (PSA) test for prostate cancer. This has multiple limitations and some would argue the jury is still out on whether PSA based testing does more good than harm.


Read more:
Four reasons I won’t have a prostate cancer blood test


What next?

The ConversationLarge trials are now underway in the US, with CancerSEEK testing being offered to thousands of healthy people. Cancer incidence and outcomes in these people will be compared to a control group who do not have testing. Study results will be available in the next three to five years.

Peter Gibbs, Professor and Laboratory Head, Walter and Eliza Hall Institute

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

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Red Star over Russia @ Tate Modern

Books & Boots

David King

In the 1970s British designer David King was sent to Soviet Russia by the Sunday Times to find old photos of Leon Trotsky. King never found them but, rummaging about in the archives, he began to uncover the vast scale of the stacks of photos, magazine and newspaper articles, posters and propaganda sheets chronicling the early years of the Russian Revolution, which had been lost or forgotten. He bought and borrowed what he could to bring back to Blighty, and then made further visits looking for more. It turned into a lifelong project. By his death in 2016 King had accumulated a collection of over 250,000 Russian Revolution-related objects which were bequeathed to Tate.

What better way to display the highlights of this vast collection than during the centenary year of the Bolshevik revolution, and so this exhibition opened on 8 November 2017, commemorating the outbreak of the…

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Jeremy Corbyn salutes Iran at a Khomeinist rally – part 1

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Three claims used to justify pulling codeine from sale without a prescription, and why they’re wrong

The Conversation

Peter Carroll, University of Sydney

From February 1, 2018 all products that contain codeine will only be available for sale in pharmacies with a prescription. This means you won’t be able to buy brands like Nurofen Plus, Panadeine or Panadeine Extra over the counter at your local pharmacy without a prescription from your doctor.

The decision was made by Australia’s drug regulator the Therapeutic Goods Administration (TGA). It was based mainly on the fact that codeine can cause dependence, and its misuse has led to addiction and even death. These facts are not in dispute.

But claims withdrawing such products from sale without a prescription will reduce codeine use are misleading. Nor is it correct to say, as some do in applauding the TGA’s decision, there is no evidence painkillers combined with lower doses of codeine aren’t any more effective in providing pain relief than the painkillers alone. Here are three common claims made about codeine-containing products that are untrue.

1. Low-dose codeine doesn’t improve pain relief

Painkillers such as codeine, ibuprofen and paracetamol act in different ways to reduce pain, and they are sometimes combined into the one tablet to produce greater pain relief. Products such as Nurofen Plus and Panadeine Extra contain 15mg or less of codeine (considered a low dose) combined with either ibuprofen or paracetamol in the one tablet.

Some doctors and organisations have claimed that painkillers, such as ibuprofen and paracetamol, are just as effective when used alone, as when they are combined with a low dose of codeine. Evidence does not support this claim.


Read more:
Why different painkillers are only effective for certain types of pain

In fact, few clinical trials have been carried out to assess how effective it is to add low dose codeine to either ibuprofen or paracetamol. And of these, some have tested doses not generally used in Australia. However, two trials have shown products containing paracetamol and codeine, and ibuprofen and codeine, in concentrations equal to those in Panadeine Extra and Nurofen Plus respectively, are effective.

An Australian study showed after dental surgery, 1000mg of paracetamol combined with 30mg of codeine phosphate (equivalent to two Panadeine Extra tablets) produced significantly greater pain relief than 1000mg of paracetamol alone (equivalent to two Panamax or two Panadol tablets).

Another study, also looked at pain following dental surgery. It showed 20mg of codeine combined with 400mg of ibuprofen (equivalent to two Nurofen Plus tablets) produced significantly greater pain relief than 400mg of ibuprofen alone (equivalent to two Nurofen tablets).

Only a very small percentage of opioid use, that includes drugs like oxycodone and codeine, is not from prescription. From shutterstock.com

2. Making codeine products prescription-only will reduce codeine use

Department of Health data give an idea of doctors’ patterns when it comes to prescribing codeine-containing products to patients under the Repatriation Benefits Scheme. Under this scheme, low dose codeine products can be obtained by veterans for a concession price with a prescription.

The data show that when doctors have the option to prescribe paracetamol combined with either 30mg, 15mg or 8mg of codeine, more than 90% of prescriptions are written for a 30mg codeine product.


Read more:
Weekly Dose: codeine doesn’t work for some people, and works too well for others

Judging by this, if current users of low dose, codeine-containing products for the short-term treatment of acute pain are forced to visit a doctor, they may potentially receive a prescription for a higher strength codeine product. This may not reduce codeine use, but could increase it.

In 2015-2016, there were more than 3.7 million prescriptions written in Australia for products containing 30mg of codeine and 500mg of paracetamol. It has also been reported most opioid (a drug that acts on the opioid receptors, such as codeine and oxycodone) use in Australia is from prescription products, with over the counter codeine products accounting for only 6% of total opioid use.

3. Taking paracetamol and ibuprofen in combination is a better way to treat pain

It has been claimed a combination product containing ibuprofen and paracetamol would fill the gap left by the unavailability of low dose codeine-containing painkillers. But there are many people who should not take ibuprofen, or only take it with caution. These include people

  • with aspirin sensitive asthma (ibuprofen may worsen their asthma symptoms, and potentially cause an acute asthmatic attack)
  • with gastrointestinal disorders such as Crohn’s disease, and those with kidney impairment (ibuprofen may make their condition worse)

Read more:
Weekly Dose: ibuprofen – just because it’s freely available, doesn’t make it safe

It also includes people taking medicines that may have a serious drug interaction with ibuprofen. These include:

  • Warfarin and other medications used to prevent blood clots (ibuprofen may increase the risk of bleeding)
  • some medicines used in the treatment of high blood pressure or heart failure (ibuprofen may increase blood pressure and reduce kidney function)
  • low dose aspirin for protection against heart attack and stroke (ibuprofen may reduce the protective effect).

Real-time monitoring

Making codeine-containing products only available with a prescription is unlikely to help those who may be misusing codeine. Pharmacies have introduced a real-time monitoring system for over the counter sales of codeine-containing products, which allows the pharmacist to identify and help those people who may be misusing them.

There is no such monitoring of prescription codeine-containing products in doctors’ surgeries. So, there is no way of identifying and helping those people who may be doctor shopping to obtain multiple prescriptions for the products.

The ConversationIt makes no sense to change from a system where the small percentage of people who may be misusing the products can be identified and helped, to one where they cannot.

Peter Carroll, Honorary Professor, Pharmacology, University of Sydney

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

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Don’t believe the Guardian. BDS is neither progressive nor non-violent

UK Media Watch

We recently posted about a motion passed by the executive council of the National Union of Students (the confederation of 600 students’ unions in the UK) to boycott Israel – one which, quite remarkably, followed a decision by the NUS last year to reject a motion condemning ISIS. Though it has almost no practical impact on the state, the anti-Israel vote comes amidst a broader recognition by commentators, pro-Israel activists and Israeli politicians of the unique strategic challenges posed by the BDS movement.

The Guardian’s Jerusalem correspondent Peter Beaumont published a piece yesterday focusing on BDS and recent comments by Prime Minister Netanyahu calling out the movement for its hypocrisy and malevolence (Israel brands Palestinian-led boycott movement a ‘strategic threat’, June 3).

In a manner similar to the Guardian’s whitewashing of the extremist student group Students for Justice in Palestine that we commented on recently, Beaumont wants his…

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The Earth is Flat

BizarreVictoria

I’ve been reading Umberto Eco’s really fun text, The Book of Legendary Lands (2013) and discovered a fun Victorian fact.

Everyone knows that in the medieval era, everyone thought the world was flat, and Columbus discovered the Americas in part because he was trying to circumnavigate the globe, to prove it was round, and to end up in India, right?

Except all of this is wrong. 

Eco tells us that people have known the world was spherical since ancient Greece. “Parmenides seems to have guessed its spherical nature, while Pythagoras held that it was spherical for mystical-mathematical reasons [and] subsequent demonstrations of the roundness of the Earth were based on empirical observations: see the texts by Plato and Aristotle. Doubts about sphericity linger in Democritus and Epicurus, and Lucretius denies the existence of the Antipodes, but in general for all of late antiquity, the spherical form of the Earth…

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