Skeptics aren't always skeptical.

Most of the people I associate with in my life could be called "Skeptics", people who exhibit some level of critical thinking when they choose between things they believe are possible and things that are either highly unlikely or actually impossible. This leads them to accept scientific research (if conducted by reputable researchers) and reject claims which are not backed by evidence. Examples would be accepting that vaccines are effective and about as safe as they can be made and that pharmaceutical drugs which have passed rigorous clinical trials are more likely to be effective than turmeric, cannabis and coconut oil in the treatment of cancer. They feel that on the balance of probabilities the white trails behind highflying aircraft are more likely to consist of condensed water vapour from jet engine exhausts rather than chemical sprays to control the population. They joke about astrology (I was predestined to be skeptical because I was born on the equinox at the cusp of Virgo and Libra) but don't think that it's very much use for predicting personality or the future.

One area in which I differ from many my friends is on the topic of science fiction. I've never been a great fan of the genre, and I've had to give polite answers when asked whether I prefer "Star Trek" or "Star Wars" (the answer is "neither"), and I have to be very careful if I feel like saying that "Dr Who" is about the most boring TV show I've ever seen.

Being entertained by fiction is not a problem in any way, but believing in fiction as if it is true certainly is a problem. This is the very thing that we criticise some of our opponents for – gullibility, going beyond the evidence and even that word to be usually reserved for people with religious conviction, "faith". It is rather disturbing when I see people who are otherwise strong skeptics suggesting the immediate possibility of things that rationality suggests are a very long way into the future.

The two examples I'd like to talk about here are human colonisation of Mars and the replacement of fossil fuel powered cars by autonomous, self driving electric vehicles.

There are five cities in Australia with a population of more than one million, but I have seen people recently claiming that a colony on Mars with a million residents is a distinct possibility within the near future. The cost, the time and the logistics of moving a population the size of Adelaide to Mars and providing all the necessary infrastructure to sustain life and accommodate them would be many times what it would cost to move Adelaide itself to Tamanrasset and make it all work in the middle of the Sahara desert.

I can imagine that within the next few decades we may be able to mine for resources on places like the Moon, the asteroids and even Mars, but the work will be done by robots not people and what we dig up and transport back to Earth will have a value that justifies the cost.

As for electric cars, I should start by saying that I think electric cars are a very good idea but without an enormous investment in charging infrastructure they are really only going to be useful in cities for a long time to come. When people say, as a friend of mine did recently, that the internal combustion engine is a totally dead technology his comment might just seem true for someone who lives 3 km from the centre of the Sydney CBD as he does. It certainly doesn't apply for the 20% or so of the Australian population who live outside of the cities.

One argument for self driving cars is that they will reduce the road toll to zero, but this can only work if everyone has one and the software is smart enough to handle all the eventualities that can happen when the car is in motion. We are a long way from that.

One suggested advantage of self driving cars is that they can go somewhere to deliver the passengers and then go somewhere else to park. While I don't think we're going to see this applied universally anytime soon, I hope we don't have to wait the three millennia since Homer wrote this in the Iliad:

Meanwhile Thetis came to the house of Vulcan, – he was making twenty tripods that were to stand by the wall of his house, and he set wheels of gold under them all that they might go of their own selves to the assemblies of the gods, and come back again- marvels indeed to see. (Translation by Samuel Butler)

And the moral of all this – skeptics are just like real people. We can believe things that just ain't so.

This article was published as the Naked Skeptic column in the November 2016 edition of Australasian Science