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. Reason is the application of logic to actual premises, with a view to drawing valid or sound conclusions. Logic is the rules to be followed, independently of particular premises, or in other words using abstract premises designated by letters such as P and Q.

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 deductive, inductive  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.

The presentism fallacy

by Tim Harding

In recent times, there has been a trend in the popular media towards viewing past events and people through the prism of present-day attitudes. This trend is manifested in attempts to ‘cancel’ the past, including by silencing discussions, banning books, tearing down statues and so on.

In historical and literary analysis, presentism is a pejorative term for the introduction of present-day ideas and perspectives into depictions or interpretations of the past. Some modern historians seek to avoid presentism in their work because they consider it a form of cultural bias, and believe it creates a distorted understanding of their subject matter. The practice of presentism is regarded by some as a common informal fallacy when writing about the past.

Presentism also fails to take into account that, at the time in which historical events occurred, those involved did not enjoy the benefit of hindsight that has informed our present perspective. Yet to fully understand an historical event, we must view it not only with the benefit of hindsight, but also in the more limited context of its own times.

To avoid the fallacy of presentism, orthodox historians restrict themselves to describing what happened and why, attempting to refrain from using language that passes judgment. For example, in analysing the history of slavery, it is more useful to study the attitudes and circumstances of the past that led to slavery, rather than just present-day attitudes that simply condemn slavery without further analysis. One theory is that African-American slavery began for economic reasons and that racism was a consequential attempt to justify the practice, rather than being the prime cause of slavery. Such a theory would be overlooked by presentism.

This fallacy should not be confused with philosophical presentism, which is a technical position in ontology (the study of existence) that only the present exists.

‘History is written by the victors’

By Roland Vargas

The adage “History is written by the victor” is common and implies that history is written from the viewpoint of the winning side. Others contend that this claim undercuts the search for objective truth and disparages the labor of historians who have earned a living by doing their jobs.

For millennia, people have used the adage “History is written by the victor” to describe how historical records can be skewed and shaped by political or cultural agendas. The historical narrative has frequently been shaped by those in authority at the expense of the viewpoints of the oppressed or vanquished.

The adage “History is written by the victors” is sometimes seen as an insult to historians since it indicates that their work is only a reflection of the prevailing narrative at the moment. They contend that it is unjust to assume that historians only parrot propaganda since they work to discover the truth regardless of the party in power.

About 60% of historians, according to a 2021 study by the American Historical Association, think that “the victors” have an excessive impact on the historical record.

Although historians want to be neutral and unbiased in their work, the truth is that they are frequently limited by the material that is accessible to them and the prejudices of the people who created it. This might result in an incomplete or biased historical record that supports the dominant narrative. Hence, in order to provide a more accurate historical narrative, it is crucial for historians to be conscious of their own biases and seek out a diverse spectrum of viewpoints.

Imagine a football game where the only person permitted to write the official game report is the coach of the winning side. Although the coach makes an effort to be neutral, they are unavoidably affected by their own prejudices and viewpoints. Saying that the coach’s report is the only correct account of the game would be unjust because the losing team and other observers could have important observations that are not included in the official report.

Historians must work to be as neutral as they can be and look for a variety of viewpoints in order to fight the prejudice inherent in the adage that “History is written by the victorious.” Looking at original sources from many sources, taking into account the viewpoints of those who were marginalized or oppressed, and being conscious of one’s own biases and limitations are all part of this.

The adage “History is written by the victors” may serve to emphasize the bias and limitations of historical records, but it is not meant to be an insult to historians who work in the field. Instead, it ought to serve as a reminder of how crucial it is to look for a variety of viewpoints and strive for neutrality while conducting historical research.

Cezanne @ Tate Modern

This is a massive, encyclopedic exhibition of paintings, watercolours and drawings by the legendary, pivotal, hugely influential French artist, Paul …

Cezanne @ Tate Modern

Policy vs rule confusion

Some people seem to be wittingly or unwittingly be confused about the distinction between policies and rules. Unwitting confusion stems from not understanding the difference in meaning between these terms. Witting confusion stems from knowing the difference, but trying soften the apparent strictness of the word ‘rule’, possibly for ideological motives.

A policy is a general guideline or principle that is used to make decisions and guide actions. It is a high-level document that provides direction for decision making, but allows for some discretion and flexibility in implementation.

A rule, on the other hand, is a specific and concrete statement that dictates a particular course of action. It is more specific and less open to interpretation than a policy, and is typically designed to ensure compliance with laws, regulations, or company policy. Rules provide a clear standard of behavior that must be followed and are typically enforceable with consequences for non-compliance.

A Dark Age Chronology

Books & Boots

Inspired by Robert Ferguson’s brilliant book, The Hammer and The Cross, I collated key dates from the so-called Dark Ages (let’s say from the departure of the Romans from Britain in 410 to the Norman Conquest of 1066). Why? Why not?

An at-a-glance summary of the period would be:

• 400 Romans leave England – Angles and Saxons invade Christian Britain
• 500 Anglo-Saxon kingdoms exist all across Britain, the Heptarchy
• 600 St Augustine comes as missionary to the pagan Anglo-Saxons
• 800 Vikings attack Lindisfarne, going on to colonise east and north England: a century of battles
• 900 Alfred the Great and successors unify the Anglo-Saxons against the Danes, creating ‘England’
• 1000 Aethelred the Unready fails to deal with repeated Viking attacks

5th century

410 Traditional date for the Romans quitting Britain. In fact it was a gradual process: 407 the army elects Constantine III emperor and he takes a…

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Histories by Tacitus

Books & Boots

Biography

Publius Cornelius Tacitus, generally referred to simply as Tacitus, was a Roman statesman and historian. He lived from 56 to 120 AD. Like many Roman writers he had an eminent career in politics and public service. He started his career under the emperor Vespasian (ruled 69 to 79) and entered political life as a quaestor in 81 or 82 under Titus (ruled 79 to 81). He became praetor under Domitian (ruled 81 to 96) in 88 and then a quindecimvir, a member of the priestly college in charge of the Sibylline Books and the Secular Games.

Tacitus gained acclaim as a lawyer and as an orator, then served in the provinces from about 89 to about 93, either in command of a legion or in a civilian post. He became suffect consul (someone appointed to replace an elected consul who had vacated their office before the completion of their year-long…

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Soviet Secret Cities: Entire Cities Hidden from The World

Utopia, you are standing in it!

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The Life of Nero by Suetonius

Books & Boots

Executive summary

Nero Claudius Caesar Augustus Germanicus was born Lucius Domitius Ahenobarbus in 37 AD. He was the fifth Roman emperor and the final emperor of the Julio-Claudian dynasty, reigning from 54 AD until his suicide in 68, aged just 33.

He was the son of Gnaeus Domitius Ahenobarbus and Agrippina the Younger, one of the daughters of Germanicus and sister to the emperor Gaius (Caligula). After Caligula was assassinated in 41 AD, Germanicus’ brother Claudius – who was Agrippina’s uncle – took the throne. Claudius took his niece as his fourth wife in 49 AD.

A year later Claudius was persuaded by Agrippina to adopt her son, Lucius Domitius, and make him his heir. Nero was 13 when he was adopted. When Claudius died (in October 54) it was widely believed that Agrippina poisoned him to ensure her son succeeded to the throne before Claudius’s biological son by his…

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The Life of Tiberius by Suetonius

Books & Boots

‘Poor Rome, doomed to be masticated by those slow-moving jaws.’
(Augustus’s dying comment on his adoptive son and successor, Tiberius, quoted in Suetonius’s Life of Tiberius, section 21)

Tiberius Julius Caesar Augustus was the second Roman emperor. He succeeded his stepfather and adopted father, the first Roman emperor, Augustus, in 14 AD. Born in 42 BC, Tiberius reigned from 14 (i.e. aged 56) until 37 AD, 23 years in total, dying at the age of 78.

Roman texts were divided into short sections, sometimes called ‘chapters’ though most are less than a page long. Suetonius’s biography of the emperor Tiberius is 76 chapters long. Like all the emperors, you can divide his biography into two parts, before he was emperor, and his reign as emperor.

The central fact about Tiberius is that he was a grumpy, unsociable and reluctant emperor who began his reign with exaggerated respect for the…

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Reflecting on Ken Frazier, skeptic

Massimo Pigliucci

by Massimo Pigliucci

Ken Frazier has passed away a few days ago. His death affected me more than I would have anticipated. We were not close friends, largely because we have lived our lives thousands of kilometers apart and had only a few opportunities to spend time together at conferences. But I have knownofKen for most of my life, and met him personally the first time in 1999. It has been an occasional, but long relationship.

Ken was the longtime editor ofSkeptical Inquirer, the premier magazine devoted to fighting pseudoscience and defending reason and science. Indeed, Ken has been the editor since the magazine changed its name from the rather unwieldy “Zetetic,” back in 1978. He has written essays ineveryissue for 35 years.

He has also published a number of books, most recentlyScience Under Siege: Defending Science, Exposing Pseudoscience. He won the…

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