Today will see the first national teachers’ strike for 21 years. Around 8000 schools will be disrupted, either partially or fully closed.

Teachers are skilled professionals. They do a tough job, working long hours and often enduring difficult working conditions. They also play a key role in society, so it’s important to attract good staff to the profession.

On the other hand, teachers are already well paid. According to Jim Knight, the Schools Minister (admittedly not a neutral source), the average salary for a teacher is £34000.

So there’s an interesting argument to be had about teachers’ pay.

However, for the most part that isn’t the argument that’s being had. Instead, the argument from the NUT (the teachers’ union that’s called the strike) that we’re hearing most is all about past levels of pay. Christine Blower, the NUT’s acting head, put it like this:

What we’re saying to the government is, if you really do value teachers, then make sure that they’re paid at least at the level of inflation - which we take to be the RPI [Retail Price Index], which is 4.1%.

The NUT’s argument is that the 2.45% pay rise that teachers have been offered is below the rate of inflation. If teachers’ pay rises more slowly than the rate of inflation, then their salaries will buy less than they used to; in real terms, teachers will have had a pay cut. And the NUT won’t stand for a pay cut.

There’s nothing in that argument about why a pay cut for teachers would be such a terrible thing, though. It doesn’t argue that teachers deserve more than they’ve been offered, or that a fall in teachers’ pay would hit recruitment, or anything like that. Instead, it’s a straightforward appeal to history, arguing that next year’s pay should be the same (in real terms) as last year’s pay.

Appeals to history are, of course, fallacies. That things were a certain way before doesn’t prove either that it was right that they were that way or that they should continue to be that way. The NUT needs to shift their focus to a better argument.

It probably wouldn’t be a great idea to try to explain that to your teacher, though. Except, perhaps, your Critical Thinking teacher.

A recent poll has shown that the public continue to support women having the right to choose to have an abortion. The poll was commissioned by Bpas, a charity that provides around 50,000 abortions each year, and conducted by Mori. 63% of those asked agreed with the statement, “If a woman wants an abortion, she should not have to continue with her pregnancy.” Bpas have reportedly cited the data collected as a reason to liberalise current abortion legislation.

There is always a concern with surveys commissioned by a group with a clear vested interest, such as this one: the way that the questions were framed might have distorted the results. Interestingly, some of the questions in this poll were varied, making it possible to see this phenomenon in action.

Half of those polled were asked about their attitude towards the current law which allows abortion up to 24 weeks with the consent of two doctors. The other half were asked about their attitude towards the current law which allows abortion up to 24 weeks but were not told about the requirement for doctors’ consent. 54% of the first group agreed with the current law, while 28% opposed it; 46% of the second group agreed with the current law, while 38% opposed it. This serves to illustrate how much difference the way that questions are framed can make.

The conclusion drawn from the data by Bpas is also of interest. If their argument were that the public endorsement of abortion implies that there is nothing wrong with it (call this “the moral argument”), then it would clearly commit the appeal to popularity fallacy. The moral status of an action and public opinion towards it are two different matters. If the majority of the population backed racial discrimination, for example, then that wouldn’t make it right.

If, on the other hand, Bpas’s argument is not to do with the moral status of abortion but with the legal status of abortion (call this “the legal argument”), then they may be on more solid ground. The argument, “The public backs abortion on demand, therefore the government should permit abortion on demand”, need not be understood as drawing a conclusion about whether abortion is morally right or wrong. Instead, it could be understood as drawing a conclusion about how the government should legislate.

Why is the second argument better than the first? Because it rests on a more plausible assumption.

The moral argument, in inferring the conclusion “There is nothing wrong with abortion” from the reason “Most people believe that there is nothing wrong with abortion”, makes an assumption: “Whatever most people believe is the case.” This assumption, however, is often false; often the majority opinion is incorrect. This is why appeals to popularity are fallacious.

The assumption made by the legal argument is slightly different. The legal argument infers the conclusion “The government should permit abortion on demand” from the reason “Most people want the government to permit abortion on demand.” The assumption made by this argument is that the government ought to do whatever most people want the government to do. This assumption is not obviously true–we can imagine situations in which following public opinion would lead to catastrophe–but it is more defensible than that made by the moral argument. In a democratic system, where the government is elected to rule for the people, the legal argument might just fly.

One thing that this shows is the importance of clarifying precisely what an argument is before it can be assessed. Several different conclusions are attributed to Bpas in several different places: e.g. that abortion should be available on demand, that the current legislation should be relaxed, and that it is time for the government to review abortion legislation. The stronger the conclusion they draw from the data, the weaker their argument gets.

Whenever there’s a strike, the workers’ union and the management fight through the media for public support. The union present arguments concluding that the workers are being treated unfairly, the management present arguments justifying their actions, and both sets of arguments are widely reported. So although strikes are a bad thing for those directly involved, at least they result in some vigorous debate in the press.

At the moment we’re in the middle of a Royal Mail strike. The workers’ complaints are many, but one is (rather predictably) that they aren’t getting paid enough. To support this claim, the Communication Workers’ Union (CWU) has pointed out that postal workers are paid less than the national average. They insist that pay should rise to the national average within five years.

What hasn’t been explained is what relevance the national average salary has to postal workers’ salaries.

The national average salary is derived from data about people in a wide variety of jobs (e.g. cleaners, sales assistants, doctors, lawyers). What’s more, the national average salary is affected by the distribution of workers in these jobs; an increase in the number of doctors, for example, would (other things being equal) increase the national average salary, whereas an increase in the number of cleaners would decrease it.

So why should we think that looking at the national average salary is a good way of decide how much postal workers should be paid? If we knew how postal workers’ hours, skills, working conditions, scarcity, and other factors affecting fair levels of pay compared to the national average, then we might be able to learn something from the comparison, but the CWU hasn’t gone into that. All they’ve given us to support their pay claim is a statistic of very questionable relevance.

The Royal Mail management have used a different statistic to imply that postal workers’ pay is good: Royal Mail postal workers earn 25% more than those who work for other companies in the sector. Whether that’s true or not, I don’t know, but I haven’t heard the CWU dispute it. Whether the Royal Mail figure is accurate or not, if we’re going to decide how much Royal Mail postal workers should be paid based on a comparison to other workers, a comparison to other postal workers seems much more useful than a comparison to the nation as a whole.