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 1700 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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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 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.
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.
An inductive argument is one wherethe 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.
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.
Psychotic disorders are severe mental health conditions. They’re characterised by a “loss of contact with reality”, where the individual loses the ability to distinguish what’s real from what’s not. Psychotic symptoms can include visual hallucinations, hearing voices, or pervasive delusional thinking.
These can often present as a “psychotic episode” – which is a relatively sudden worsening of psychotic symptoms over a short time-frame, frequently resulting in hospitalisation.
The heaviest users of cannabis are around four times as likely to develop schizophrenia (a psychotic disorder that affects a person’s ability to think, feel and behave clearly) than non-users. Even the “average cannabis user” (for which the definition varies from study to study) is around twice as likely as a non-user to develop a psychotic disorder.
Furthermore, these studies found a causal link between tetrahydrocannabinol (THC – the plant chemical which elicits the “stoned” experience) and psychosis. This means the link is not coincidental, and one has actually caused the other.
People with certain gene variants seem to be at higher risk. However our understanding of these factors is still limited, and we’re unable to use genetic information alone to determine if someone will or won’t develop psychosis from cannabis use.
Those with these genetic variants who have also experienced childhood trauma, or have a paranoid personality type, are even more at-risk. So too are adolescents and young adults, who have growing brains and are at an age where schizophrenia is more likely to manifest.
The type of cannabis material being used (or the use of synthetic cannabinoids, known as “spice”) may also increase the risk of psychosis. As mentioned above, this is due to the psychological effects of the chemical THC (one of over 140 cannabinoids found in the plant).
This compound may actually mimic the presentation of psychotic symptoms, including paranoia, sensory alteration, euphoria, and hallucinations. In laboratory-based research, even healthy people may exhibit increased symptoms of psychosis when given THC compounds, with more severe effects observed in people with schizophrenia.
Many cannabis strains contain high amounts of THC, found in plant varieties such as one called “skunk”. These are popular with consumers due to the “high” it elicits. However with this goes the increased risk of paranoia, anxiety, and psychosis.
But can’t cannabis also be good for mental health?
Ironically, one compound found in cannabis may actually be beneficial in treating psychosis. In contrast to THC, a compound called cannabidiol (CBD) may provide a buffering effect to the potentially psychosis-inducing effects of THC.
This may occur in part due to its ability to partially block the same brain chemical receptor THC binds with. CBD can also inhibit the breakdown of a brain chemical called “anandamide,” which makes us feel happy. Incidentally, anandamide is also found in chocolate and is aptly named after the Sanskrit word meaning “bliss”.
CBD extracted from cannabis and used in isolation is well-tolerated with minimal psychoactive effects. In other words, it doesn’t make a person feel “high”. Some studies have found CBD is actually beneficial in improving the symptoms of schizophrenia. But one more recent study showed no difference in the effects of CBD compared to a dummy pill on symptoms of schizophrenia.
Perhaps this means CBD benefits a particular biological sub-type of schizophrenia, but we’d need further study to find out.
Would legalising make a difference?
It’s important to note most studies finding a causal link between cannabis use and psychosis examined the use of illicit cannabis, usually from unknown origins. This means the levels of THC were unrestricted, and there’s a possibility of synthetic adulterants, chemical residues, heavy metals or other toxins being present due to a lack of quality assurance practices.
In the future, it’s possible that standardised novel “medicinal cannabis” formulations (or isolated compounds) may have negligible effects on psychosis risk.
Until then though, we can safely say given the current weight of evidence, illicit cannabis use can increase the risk of an acute psychotic episode. And this subsequently may also increase the chances of developing schizophrenia. This is particularly true when high-THC strains (or synthetic versions) are used at high doses in growing adolescent brains.
Public discussion of rail links to airports has been narrowly focused on the idea of a single line and where to run it. In Melbourne, the politics of this debate has so far prevented a railway from being built, because it is not possible for one line to meet all of the landside access needs of the airport.
The issue of rail access for a new western Sydney airport has also not been resolved.
In terms of passenger demand, Shanghai Pudong and Bangkok Suvarnabhumi were comparable in 2012 with where Melbourne will be in 2019. London and Bangkok have populations of around 8 million, have other airports and have much greater numbers of passengers transferring within them than Melbourne Airport, but the most salient comparison is the means of landslide access.
We’ll look more closely at Heathrow, one of the more comparable airports to Melbourne, later in this article.
The political divide on a rail link
The history of planning for a Melbourne Airport rail link has been dogged by party-political differences focused on the idea of a single railway and the question of its route out to Tullamarine. Traditionally, the Coalition parties have favoured the express proposals, while the Labor Party has preferred alignments that benefit local commuters.
This difference and the impossibility of resolving it with a single line would be one of the reasons we have so far not gone to the bother of actually building anything. It has also distracted attention from more incremental ways to improve landside access to the airport beyond the SkyBus. Its market is similar to the main targets of the express route proponents.
The most recent express proposal is the AirTrain by the highly respected Rail Futures Institute (RFI). It’s part of a bold plan to separate Victorian regional services from the metropolitan commuter network. This would eventually provide statewide fast rail services, including a 15-minute ride between the airport and Southern Cross Station in the city centre.
The benefits of and urgent need for RFI’s AirTrain proposal are clear. But it still won’t solve all of Melbourne Airport’s landside access demands, nor will it have the city-shaping potential in the northwest region between Tullamarine and the CBD that’s driving the ideas for an airport metro service.
Prime Minister Malcom Turnbull’s embrace of these ideas is a welcome change from his side of politics, as is Premier Daniel Andrews’ apparent support for RFI’s proposal. These are amusing reversals of political positions on airport access, but the community should not be swayed by the potential for wedging.
We can learn from Heathrow
To understand our predicament of airport access, comparisons with London’s Heathrow are useful. Many Australians know this airport and its landside access demands are far more similar to those of Melbourne Airport than may be imagined.
The Piccadilly Tube line was extended to Heathrow in 1977. That was a decade before it was serving over 30 million passengers comparable to what Melbourne airport was serving in 2013.
In 1998, Heathrow added a 15-minute express rail line to Paddington Station, when its landside access needs were about 40 million. That’s the demand Melbourne Airport is projected to hit in 2019. When London’s Elizabeth line (formerly CrossRail) opens next year, it will connect Heathrow to a major east-west line similar to the Melbourne Metro.
In 2028, Melbourne Airport is projected to hit the same level of landside access demand as Heathrow experienced in 2017. Currently, 40% of passengers using Heathrow do so via public transport – 27% via rail, 13% via bus or coach. And 35% of airport staff use public transport, and this is rising.
Heathrow has 13 public bus lines, 27 coach services and three railway services – the stopping-all-stations commuter service on the Piccadilly line and two levels of express service at premium ticket prices on regional railways (which will be subsumed by CrossRail).
By comparison, even though it is one of the world’s busiest, Melbourne Airport has a mere four public buses, some regional coaches and private express bus services. As a result, 86% of access is by car, including 17% by taxi or limo. SkyBus would take the lion’s share of the 14% bus/coach access.
A wider spread of frequent public buses would be easy to implement. Extending the 59 tram service by 7km from Airport West would also be relatively quick and easy. Light rail lines to the airport from La Trobe University and Deer Park would provide much-needed connections to the main commuter rail system in parts of the metropolitan area where public transport is far worse than average.
A genuine commuter metro to the airport would not try to be an express. It would have stations that connect the major and emerging employment centres, such as Airport West, Essendon Fields, Niddrie, Highpoint, Footscray Hospital and Victoria University, and heavy rail stations at Arden and North Melbourne, before connecting with Southern Cross and then Bourke Street, Parliament Station and on to those eastern suburbs where metro services have long been planned.
The politics of airport access need to be shifted away from focusing on whether one rail route is better than another to the need for a comprehensive transport plan integrated with land use that shows how we can shape our city and our state for a better future.
You may have noticed that I don’t opinionate on quantum mechanics. Or jazz. The reason for this is that — although I’m very interested in both topics — I just don’t know enough about them. Not enough to be able to offer an informed opinion, at any rate. So I sit back, read what other, more knowledgeable people have to say about quantum mechanics and jazz, form my own second-hand opinion, and try to avoid embarrassing myself by pontificating in public.
Today in 1955, East Germany became a sovereign country. Officially sovereign according to the Soviet Union that is. At that time, the German Democratic Republic was still occupied by the Red Army, its capital city of East Berlin remained legally under the control of a council of the four Allied powers, and as a state it was only recognized by the USSR, fellow Eastern Bloc countries, and Yugoslavia. So was it a sovereign country or not?
Continuing my journey through the Top 100 Greatest American Movies of All Time (1912-1996) I watched the number 2 spot which I heard a lot about and its quality, Casablanca by Michael Curtiz. I’ve finally watched it and must say it is a lot of things I didn’t anticipate being. I knew it belonged to the romantic genre which gets any guy calling for a death wish when watching alone however, to my surprise I survived, and liked it a lot. It takes place in, like the title says, Casablanca, Morocco during WWII, a time when it was under France which itself is under the Nazi Germany occupation. It’s a refugee bus stop, a final spot for many to get to America, the safe haven. In all this we got a bar owned by the American main hero, Rick who “happens” to intervene a lot by helping…
Beer is the most consumed alcoholic beverage in the world; it is also the most popular drink after water and tea. In the modern world, however, little consideration is typically given to how beer developed with respect to taste. Even less is given to why beer is thought of in the way that it is.
But today, Canada is in the middle of a beer renaissance. A relative explosion of craft breweries has led to a renewed interest in different methods of brewing and in different types of beer recipes.
In turn, this has driven interest into historical methods of brewing. It is a rather romantic idea: That very old brewing processes are somehow superior to those of the modern world. While almost all of the beer on the market today is quantitatively and qualitatively better than that produced in the ancient world, attempts made by both historians and breweries recently have had some good results.
From an academic point of view, researchers have realized eating and drinking are important social, economic and even political activities. In the ancient world, food, drink and their consumption were important indicators of culture, ethnicity and class. Romans were set apart from non-Romans in several ways: Those living in cities versus those who didn’t, those who farmed in one place versus those who moved around, and so on.
One of the other ways in which this distinction was made was in the different foods people ate and in the liquids they drank. This is clear in the ancient Graeco-Roman debate surrounding those who drank wine and those who drank beer.
Although the saying “you are what you eat” is a fact in terms of physiology, the Romans also believed that “you are what you drink.” So Romans drank wine, non-Romans drank beer.
So the re-creation of ancient beer and mead (an alcoholic beverage made by fermenting honey and other liquids) allows us to examine many things. Among them are these cultural and ethnic considerations, but there are other important and interesting questions that can be answered. How has the brewing process transformed? How have our palates changed?
The “Roman” recipes and their recreation
The Romans left us a variety of different recipes for food and drink. Two of them form the basis of an ongoing research project between the co-owners of Barn Hammer Brewing Company — Tyler Birch and Brian Westcott — and myself that attempts to answer some of these questions.
The first is a recipe for beer that dates to the fourth century Common Era (CE). It appears in the work of Zosimus, an alchemist, who lived in Panopolis, Egypt, when it was part of the Roman empire. The second is a recipe for a mead probably from Italy and dating to the first century CE, written by a Roman senator called Columella.
Both recipes are quite clear concerning ingredients, with the exception of yeast. Yeast, or more appropriately a yeast culture, was often made from dough saved from a day’s baking. Alternatively, one could simply leave mixtures out in the open. But the processes and measurements in them are more difficult to recreate.
The brewing of the beer, for instance, required the use of barley bread made with a sourdough culture: Basically a lump of sourdough bread left uncovered. To keep the culture alive while being baked required a long, slow baking process at a low temperature for 18 hours.
Zosimus never specified how much water or bread was needed for a single batch; this was left open to the brewers’ interpretation. A mix of three parts water to one part bread was brewed and left to ferment for nearly three weeks.
The brewing of the mead was a much easier process. Closely following Columella’s recipe, we mixed honey and wine must. The recipe in this case provided some measurements, and from there we were able to extrapolate a workable mix of roughly three parts must to one part honey.
We then added wine yeast and sealed the containers. These were placed in Barn Hammer’s furnace room for 31 days in an attempt to imitate the conditions of a Roman loft.
What did we learn?
First of all, it’s worth noting that the principles of brewing have not changed significantly; fundamentally, the process of brewing both beer and mead is arguably the same now as it was 2,000 years ago. But as true as that may be, even now the production of Zosimus’ beer — particularly the baking of the bread — was labour-intensive.
This led to another question: Did the link between baking and brewing depicted so clearly in ancient Egyptian material culture and archaeology persist even centuries later?
Second, we recreated beer and mead from the Roman Empire as faithfully as we were able. The data all suggest that the beer is a beer, and the mead is a mead, right down to the pH level: The beer, for instance, stands at pH 4.3 which is what one would expect from a beer after fermentation.
Third, as the photos here make clear, the mead looked like red wine, the beer was quite pale but cloudy. Neither case was particularly surprising, but what was interesting was the difference between the first tasting of the beer and the second 10 days later.
In the former, the beer looked liked a sourdough milkshake; in the latter, the beer looked like a pale craft ale, and one that would not be out of place in the modern craft beer market.
Fourth, with respect to taste, the beer was sour but quite smooth, and had a relatively low ABV – Alcohol By Volume: the measurement that tells you what percentage of beer or mead is alcohol — around three to four per cent. The sour taste resulted in diverse opinions: Some people liked it; others hated it. The mead was incredibly sweet; it smelled like a fortified wine due to presence of Fusel alcohols, and had an ABV upwards of 12 per cent.
While general tastes may have changed, there are modern palates that appreciate ancient beer and mead. Is this a physiological question? Perhaps, but what seems clear is that ancient indicators based on what people drank are likely more indicative not only of the Romans’ beliefs and opinions about non-Romans, but also their prejudices against them.
Ultimately, what the project suggests so far is that while the brewing process may not have changed that much, in some ways neither have we.