Don't let straw men give you hay fever.

In my last column I talked about the futility of using straw man arguments in debates. A straw man is a statement of your opponent's belief or position which is wrong. I also said that the use of such arguments is usually due to ignorance, and advised that it is wise to actually research your opponent's position before going into battle if you don't want to look foolish.

There are some discussions, however, which will almost certainly result in the appearance of a straw man argument, and part of your research into your opponent's position is to predict such usages and be prepared for them. If you are not prepared, a straw man, like non sequitur, can divert the conversation, waste your time and make you, the recipient, look foolish, unprepared and maybe even dishonest.

There is an Internet tradition dating back to the days when Usenet was the most popular forum for discussion which still applies in the Facebook era. It is Godwin's Law, and in its original form was "As any Usenet thread gets longer, the probability that Hitler or the Nazis will be mentioned gets greater".

There needs to be a new such law which states that in discussions with certain classes of people, the probability that a straw man argument will surface increases with time.

Here are a few examples of inevitable straw men that will appear if you attempt to debate certain people.

Climate change deniers have three they regularly use. The first is attempting to confuse weather with climate. Where I live, the weather right now is hot and dry. Six months ago it was almost constantly raining; in four months the roads will be closed by snow (but not as often or with as much snow as happened 30 years ago). That's weather. Climate is weather events smoothed over time – the grapes in the vineyards now ripen a few weeks earlier than they did a decade or so ago, and before the recent rain (the heaviest for 50 years and coming at a different time of the year than farmers remember) the local dam was at its lowest for a very long time. The climate is changing, and one piece of evidence for this is increased variability of the weather.

Another straw man, which really should be called "cherry picking", is to point to a series of years that show a decreasing average temperature. This is a dishonest use of statistics and the sort of thing I was warned about in my first stats course at university. The third is to refer to and discredit research done by the Intergovernmental Panel on Climate Change. To quote from the IPCC's web site "It does not conduct any research nor does it monitor climate related data or parameters". But the deniers know that.

Vaccine opponents also have several straw men that appear. One is that vaccines are "injected directly into the bloodstream", bypassing the body's natural protective barrier. No vaccines are injected into the bloodstream, but having to explain this can take up valuable time. Another is to claim that vaccines are not tested for safety. I once responded to this claim by linking to a list of several thousand scientific papers, only to be asked if I had read all of them myself and if I could confidently state that they weren't all the same single study constantly repeated. (Sometimes you just have to give up. I did.) They will often say "You claim that all vaccines are 100% effective and absolutely safe". No we don't, but again time can be wasted pointing this out.

The one which is always a lie because they know the truth is that vaccines contain "mercury". No childhood vaccine has contained the preservative thimerosal since 2000, and it is almost non-existent now. But the deniers know that.

There is also the regular claim from vaccine deniers and supporters of alternative "medicine" that the American Medical Association (and the Australian equivalent, because "AMA") controls the manufacture and distribution of vaccines and drugs. The AMAs (both of them) are non-compulsory doctors' trade unions and might have input into government policy decisions but don't make or enforce the rules.

The final group of regular straw man users is the creationists. They use too many to list here, but the best is probably "Evolution can't explain the origin of life". That isn't its job – evolution explains how we got to here from there. In one debate I tried to squash this by saying "God did it" but I was told that as an atheist I wasn't allowed to say that.

We have to resist using straw man arguments ourselves, but we always have to expect that some will come over the net towards us. Be like the Boy Scouts, and "Be Prepared".

This article was published as the Naked Skeptic column in the March/April 2017 edition of Australasian Science