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).


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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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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Trump administration weakens Endangered Species Act

Why Evolution Is True

Everything the Trump administration does seems aimed in the wrong direction, but as a biologist, I’m really pissed off at this latest bit of stupidity. Read the NPR or NYT articles below (click on screenshots) to see the latest debacle:


Here are some of the changes. The new regulations:

  • weaken protections for species listed as “threatened”: one step below “endangered”;
  • allow future listings to be based partly on economic assessments (the NYT says, “for instance, lost revenue from a prohibition on logging a critical habitat”) rather than on science alone. This is a first, and something the original Act aimed to avoid.
  • make it easier to remove species from the “endangered” list;
  • limit the nature and amount of habitats are considered when deciding whether a species is listed as “endangered”. Environmental groups claim that this will make it harder to protect species at risk from warming climates, which alters…

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A tidal wave of beneficent trends

by Martin Bridgstock

(An edited version of this book review was published in The Skeptic magazine, September 2018, Vol 38 No 3)


Some years ago Steven Pinker’s book, The Better Angels of Our Nature (Pinker 2012) made a great impression. In this book – using over a thousand pages of text and 100 diagrams – Pinker supported his case that, over the long run, human beings are becoming less violent toward each other.  There were exceptions to the decline in violence, but Pinker seemed to make a powerful case for his argument. In addition, he presented a list of factors which, in his view, led to this decline in violence.

Since that time, Pinker’s argument has been verified. Johan Norberg (2016), a Swedish writer and Angus Deaton (2013), a Nobel prize-winner in economics, have come to the same conclusion. The key finding, the long-term decline in interpersonal violence, has to be welcome to everyone. Its sheer magnitude sometimes takes an effort to grasp. For example, an Englishman living in the 1300s was twenty times as likely to die violently as an Englishman in the twentieth century (Pinker 2016:73). Overall, Pinker’s case for the trend away from violence seems to be well supported.

Many wonderful trends

Now Pinker has returned with another book, titled Enlightenment Now (Pinker 2018). It is short compared to the other book – only 550-odd pages and 75 diagrams – but far more ambitious. He documents the evidence that the human condition is improving on more than a dozen important measures. And he has a single underlying theory to explain this.

Rather than list all the trends, I will put them in a separate table, with an example or two for each. Cast your eyes over the table. I suggest looking at the examples for Life, Wealth and Knowledge. Let me stress that in the hundreds of pages and dozens of illustrations which make up Pinker’s book, there are far more trends than I can list here. And all point in the same direction: the human condition worldwide is improving. Usually these improvements took place first in Europe and North America. However, the other parts of the world are improving too, and usually catching up with the leaders. 

Table 1. Major trends charted by Pinker, with selected examples

 Life. Life expectancy is increasing Around 1780, world life expectancy for humans was about 30 years. Today it is 71.4 years. (Pinker 2018: 53-4 )   Major diseases are in decline, often because of mass vaccination (Pinker 2018: 64).

Sustenance. The food supply per person is increasing and so childhood stunting and famine deaths are in decline (Pinker 2018: 70-71). The size of families is decreasing, too: apparently once parents are reasonably sure that their children will survive, they stop having large families (Pinker 2018: 125).

Wealth. GDP per capita is increasing worldwide and as a result extreme poverty is falling. In 1820, nearly 90% of the world’s population lived on US$1.90 (2011 dollars) or less. Today only about 10% live on so little (Pinker 2018: 87).

Inequality. Inequality may be increasing, but the general trend is for everyone to become richer (Pinker 2018: 120)

The Environment. Because of advancing technology, the risk of environmental catastrophe is receding, and most environmental indicators are improving (Pinker 2018:132-3).

Peace. The peaceful trends discerned in Pinker’s earlier book are shown to have continued (Pinker 2018: 157-9).

Safety. Steady reduction in vehicle accident deaths, plane crash deaths and most other forms of accidental death (Pinker 2018: 179-182).

Terrorism. Worldwide, deaths by terrorism are dwarfed by those from war and accidents (Pinker 2018: 192)

Democracy. Despite recent hiccups, Pinker cites the Polity Project as showing a steady advance for democracy in the world ( (Pinker 2018; 207).

Equal rights. A general rise in liberal values in nearly all areas of the world over the last 50 years (Pinker 2018: 227). A decline in racist, sexist and homophobic jokes on the internet (Pinker 2018: 218).

Knowledge. Great rises in literacy worldwide (Pinker 2018: 238). Back in 1475 20% or less of the people in European nations were literate. Today over 90% are, and the rest of the world is improving too.

Quality of Life. Decline in working hours in Europe and the USA, decline in housework hours, rise in useful household devices. Increase in leisure time (Pinker 2018: 249-256)

Happiness. Reported life satisfaction is correlated with physical wellbeing, and seems to be improving (Pinker 2018: 269-279)

Existential Threats. The worldwide stock of nuclear weapons is diminishing (Pinker 2018: 318), and doom-laden predictions have repeatedly been proved wrong  (Pinker 2018: 309)

The Cause of It All

However, Pinker is not simply a Pollyanna, exclaiming at how wonderful everything is. He has a theory as to what underlies all these wonderful trends, and he also thinks that there is a threat to the entire process. As the title of his book suggests, he regards the Enlightenment as being a key cause of all this human improvement.

What do we mean by the Enlightenment? Pinker concedes that, unlike the Olympics, there was no opening and closing ceremony: you can argue about it endlessly (Pinker 2018: 7-8). However, he distinguishes some features of Enlightenment thinking.  One theme is the use of reason, which leads to doubt and questioning. Another is the refinement of reason to understand the world. (Personally I regard this as an extension of reason, or using it in a special way.) Part of this understanding involves knowing ourselves, and how our minds and bodies work. A third attribute is humanism, involving a morality which privileges human welfare. Finally there is a belief in progress. Pinker stresses that these basic themes are not absolute: people are not completely reasonable, nor is progress guaranteed.

As he works through all the trends operating in the world today, Pinker tries to link them back to Enlightenment influences. For example, Enlightenment thinking values commerce because it involves free exchange and economic improvement. Although commerce can be tough at times, it creates wealth and is far, far better than war, destruction and murder. Again, Enlightenment thought leads to the questioning of cruel judicial punishments.

In my view, the least convincing of Pinker’s arguments is the one over inequality. His chapter on this is largely a response to the French economist Thomas Piketty (2013). Using massive amounts of evidence, Piketty argued that western nations are becoming less equal. Capital, for several decades, has grown faster than wages, and this means that the top few per cent of the population are accumulating more and more wealth, while the bottom half are making almost no progress at all. Pinker’s counter-argument is that, in absolute terms, even the poorest people are better off than they used to be (Pinker 2018: 97-120). My personal view is that if some people are becoming poorer relative to everyone else, it is little comfort to learn that they are better off than previous generations. I suspect that events like the election of Trump and the vote for Brexit are at least in part an outburst against adverse economic trends.

Unlike the earlier book, Enlightenment Now has attracted a great deal of criticism. One reason is that Pinker focuses a good deal of scorn on western liberal intellectuals, who are overwhelmingly gloomy about society and the way it is going.  As Pinker points out, this gloom is not based on evidence, and again and again has been shown to be unjustified (Pinker 2018: 39-52). He has a series of explanations as to why intellectuals argue — wrongly – that things are getting worse. One explanation is the relentless focus of the popular media on violence: no matter what the overall crime rate, if there is a drug-crazed shooting or an atrocity, the media will focus upon it. This distorts our understanding because we use the ‘Availability heuristic’ (Pinker 2018: 41-2). When we readily remember an event, we assume things generally are like that event. So we may be disgusted by what has happened in Syria or the Yemen, or what was done to the Rohingya and regard these as characterising our age. As Pinker argues, however, in previous ages there were far more such atrocities, and they were accepted almost without comment. In addition, gloomy pessimism is often regarded as being far more profound than optimism – even when the optimism is supported by evidence and the pessimism isn’t.

Another reason why Pinker’s book has attracted criticism is because of what he calls ‘counter-Enlightenments’ (Pinker 2018: 29-35). The Enlightenment has suffered a series of reactions from religious and nationalist groups, and also from ideologies of the right and left. These movements do not accept evidence-based arguments and so are uncomfortable with the optimistic message of Pinker’s book. He makes this explicit when, partway through, he writes:

In writing the chapters on progress, I resisted pressure from readers of earlier drafts to end each one by warning, “But all this progress is threatened if Donald Trump gets his way.” Threatened it certainly is (Pinker 2018: 334)

Then he reviews the progress achieved in various fields, and points out that President Trump’s actions and words appear to oppose nearly all of it. In addition, the various nationalist outbursts in Europe could also threaten further progress. There is, Pinker stresses, nothing certain about continued improvements, and so the Enlightenment is well worth defending.

Science and Skepticism

Now the Enlightenment is the basis for two other important features of modern society. One is science, the other skepticism. Pinker (2018: 392-3) points out that science rests on two key ideals. One is that the world is comprehensible to our minds. This is borne out by the success of science. The other assumption is that we should allow the world to tell us what it is like. The traditional sources of belief, and the traditional authorities, are generators of error. Only by carefully formulating theories, and being willing to accept that the evidence may show them to be wrong, can we make scientific progress.

Skepticism, of course, stems from a similar set of ideals. Skeptics examine certain types of belief and question whether they are supported by evidence. It does not matter to skeptics who holds certain beliefs, or whether they stem from one ideology or another. The key question is, does the world tell us that they are true?

Is Pinker right?

Broadly, there are two different ways in which Pinker’s argument can be questioned. Is his evidence for massive, worldwide progress in a whole range of fields justified? And is his stress upon the Enlightenment as a key element in this progress justified? The answer to the first question is almost certainly yes. Pinker makes his sources of information clear, and it is easy to check them. He gets his facts right. The second question is more complex. Norberg (2016) for example, uses the same evidence as Pinker, but traces the improvements to free enterprise rather than the Enlightenment. My personal judgment is that the Enlightenment is a key feature in current progress, but not the only one: If we discard Enlightenment thought, we will suffer in the long run.

As a retiree, I have often worried about what kind of a world we are leaving our children and grandchildren. The short answer appears to be: with some exceptions, a lot better than the world we found. Provided we don’t lose sight of Enlightenment values, the future promises to be much better than the past.


Deaton, Angus (2013) The Great Escape. Health, wealth and the origins of inequality. Oxford and Princeton, Princeton University Press.

Norberg, J. (2016) Progress: Ten reasons to look forward to the future. London, Oneworld.

Piketty, Thomas (2013) Capital in the twenty-first century. Cambridge, Mass., Harvard University Press.

Pinker, Steven (2018) Enlightenment Now.  The case for reason, science, humanism and progress. London, Allen Lane.

Pinker, Steven (2012) The Better Angels of our Nature. London, Penguin.

(Reblogged with the permission of both the author and the Editor of The Skeptic).

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The Penguin History of Latin America by Edwin Williamson (revised edition 2009) (1)

Books & Boots

Because it comes with the bright orange and white spine of the new-style Penguin histories, and because it said ‘New Edition’ on the front cover, I hadn’t quite grasped that the main body of this hefty 700-page history of Latin America was completed by 1990. The new edition is ‘new’ because it adds a 40-page chapter at the end, summarising events in Latin America between 1990 and 2008.

The text is divided into three big parts:

  • The Age of Empire pp. 3-192 (189 pages)
  • The Challenge of the Modern World pp. 195-310 (115 pages)
  • The Twentieth Century pp. 313-566 (253 pages)

Note how the section on the 20th century, plus the forty pages of the ‘new’ chapter, is as long as the first two parts put together. Here, as everywhere, the more recent the history, the more of it there is, the more people there have been (the higher the population)…

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What identity politics did to Rosanna Arquette

Why Evolution Is True

The actor Rosanna Arquette, who has become a woke activist, tweeted this out yesterday. When I went back to retrieve it, I found that she had “protected” her Twitter feed so that I couldn’t embed the tweet. Fortunately, someone took a screenshot:

Her feed now (note that “silence is complicity”):

I was a big fan of Arquette’s performances in Desperately Seeking Susan and especially as Gary Gilmore’s girlfriend in The Executioner’s Song, but this self-flagellation is shameful. What does it accomplish? Does it help people of color? I don’t think so. What it does is demonstrate Arquette’s bona fides as a Woke Person, as well as reinforcing the kind of racism that deems all white people as oppressors and “the other”.   I seriously doubt that Arquette was either a racist or an oppressor, and so why is she ashamed? Is she ashamed that she has the skin…

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The Emerald Tablet (Benedict Hitchens #2), by Meaghan Wilson Anastasios

This review contains a link to ‘The Sceptical Chymist’ essay on this blog.

ANZ LitLovers LitBlog

The Emerald Tablet is not my usual reading fare, but I enjoyed it.  Written by Melbourne author Meaghan Wilson Anastasios who has a career in archaeology in the Mediterranean and the Middle East behind her and now uses her expertise to work as a researcher for film and TV, the novel has been described in a Saturday Age review as pure escapism in the mould of Dan Brown or Indiana Jones.’  But though I think the flawed main character has the same kind of charisma as Harrison Ford, I think The Emerald Tablet is infinitely better than anything by Dan Brown on which I confess to having wasted my time.

The book begins with a well-constructed introduction that includes all the central characters, alludes to the quest that drives the narrative, and provides just enough of the geopolitics of the 1956 Suez Crisis to bring the reader straight to the…

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An unwise tweet by Neil deGrasse Tyson, and some statistics on gun deaths

Why Evolution Is True

I guess Tyson was trying to make a point about data and how we receive it when he issued the tweet below yesterday, but it was surely ill-timed—and also somewhat misleading.

It clearly looks crass and uncaring. SFgate discusses some of the pushback, including this tweet from a lawyer and writer:

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Readers’ wildlife photos

Why Evolution Is True

Today we have some lovely garden birds from reader Paul Peed, whose notes are indented and whose images available at eBird and Instagram.

Some favorites from my gardens
My gardens are Audubon Native Plant gardens which beside using far less water tend to attract a variety of birds, bees, butterflies and other visitors. The most colorful of the avian visitors is the Painted Bunting (Passerina ciris).  Here is a male enjoying my west birdbath.
Painted Buntings have visited my gardens for 5 years running.  This year they fledged 3 young.  Below is the male with an immature male or female newly fledged.

Breeding populations of Painted Buntings have been affected by the illegal cage bird trade.

A Ruby-throated Hummingbird (Archilochus colubris) visiting a native Yellow Necklacepod (Sophora tomentosa) near the east birdbath.

A Brown Thrasher (Toxostoma rufum) visits my west birdbath for…

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House passes anti-BDS bill by wide bipartisan margin: three of “the squad” (along with 13 other Democrats) dissent

Why Evolution Is True

If you don’t know about B.D.S. (Boycott, Divestment, and Sanctions) movement, the New York Times article below, from Saturday, will give you the basics. As for the title question, well, it’s not answered; the article gives the views of both supporters and detractors of BDS.

I’ve always thought the movement was anti-Semitic, but even if you don’t agree, it’s clearly aimed not just at pressuring Israel to arrive at a land settlement with Palestine—an aim, if not a tactic, that I agree with—but to eliminate the state of Israel completely, at least as a Jewish state. In the end, the movement’s aims will result in a big “Israel” with an Arab majority, and that would be the finish, not just of a Jewish state, but of the Jews themselves. And that is the movement’s aim.

Here are the aims of BDS as the Times shows them:

Modeled on the fight…

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Cockatoo removes bricks securing the lid of a trash can

Why Evolution Is True

Finally, to end your Saturday, here’s a video from Australia of a cockatoo shoving three bricks off of a garbage bin to get at the noms inside. It reminds me of a cat knocking stuff of a table, but the cats do it just to mess with people, while the cockatoo is creatively foraging:

We’ve recently moved into Helensburgh, NSW, Australia. A very beautiful area but we’ve got these clever/pesky Cockatoo’s [sic: the greengrocer’s apostrophe!]. Lots of people put rocks and bricks on their bins to keep them out but these birds have learnt to push the bricks off to get the rewards.

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The “grievance studies” hoax: a forum at the Chronicle of Higher Education

Why Evolution Is True

The “grievance studies” hoax conducted by Helen Pluckrose, Peter Boghossian, and James Lindsay is now so well known that it has its own Wikipedia page. I’m sure most of you know some details: the trio wrote and submitted 20 papers to journals dealing with what they call academic “grievance studies”: cultural, queer, race, gender, fat, and sexuality studies. At least seven of the papers were published, including the famous “dog park rape culture” paper, and one even won a prize.  And one of the accepted papers was larded with extensive quotations from Mein Kampf.

Just this week Boghossian, the only hoaxer who has a formal academic position, was disciplined by Portland State University, which, although it didn’t fire him, ordered him to take training in “protection of human subjects.” Until he does that and then convinces the University he understands the rules, he cannot do sponsored research, work on human subjects, or apply for…

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