1. © Colin Frayn, 2008 www.frayn.net The Straw Man Setting up a weaker version of a theory, claiming (falsely) that this is the true theory, and then disproving it. Example: “Scientists claim that a totally random process created order. Of course, that’s impossible” Reply: “No, scientists do not claim this. Evolution is a highly nonrandom process, driven by natural selection.”

2. © Colin Frayn, 2008 www.frayn.net Relying on Intuition Any argument that relies on human intuition, instead of actually working out probabilities with rigorous analysis. Example: “It’s obvious to anyone that the eye cannot have evolved – it’s just too unlikely.” Reply: “On what analysis do you base your assertion that the evolution of the eye is too unlikely? Actually, scientists have analysed the likelihood of an eye evolving and found that it was remarkably straightforward, taking less then half a million years.”

3. © Colin Frayn, 2008 www.frayn.net False Dichotomy Presenting two choices, disproving one (or attempting to) and then claiming that the other is the only alternative. Example: “Scientists can’t yet describe the exact process by which inorganic molecules because living things, therefore God did it.” Reply: “There’s a third option: we don’t yet know how this happened, but it did happen through natural means. Our lack of understanding is an incentive to do proper scientific research, not to give up and abandon any further investigation. That latter option is intellectual cowardice.”

4. © Colin Frayn, 2008 www.frayn.net Personal Arguments Arguments from, or against, authority. Claiming that someone is correct because they are clever, or that they are wrong because of some irrelevant attribute of their personal life. Example: “Fred Hoyle said that evolution was nonsense, and he has a Nobel prize!” Reply: “Science isn’t a sort-of oligarchy where the people with the most letters after their name get to decidee on what’s right or wrong – on the contrary, scientific theories need to be presented with their evidence, and that evidence should be evaluated on its merits, no matter who presented it. As it happens, in this particular case, Hoyle woefully misunderstood the arguments for evolution.” Example: “Darwin recanted on his death bed, therefore evolution is false.” Reply: “Actually, the story about Darwin allegedly recanting his theory on his death bed is a total fabrication – he did no such thing. But even if it had been true, it would have been irrelevant. Again, theories stand or fall based on the evidence that supports them, not by virtue of the scientists who support or oppose them.”

5. © Colin Frayn, 2008 www.frayn.net The Underdog Claiming that all great ideas are initially opposed by everyone, and then they gain acceptance. Example: “Everyone laughed at Einstein when he said light travelled at a constant speed; just like they are laughing at creationists now.” Reply: “Actually, surprisingly few people laughed at Einstein. Also, Einstein came forward with evidence for his theory of relativity. Great theories may often be initially rejected, but most theories that are initially rejected are not great – most are just dumb.”

6. © Colin Frayn, 2008 www.frayn.net Absolute Proof This is related to the old maxim “absence of evidence doesn’t imply evidence of absence” – just because you can’t prove something is true, it doesn’t mean it’s false (and vice versa). Example: “You can’t prove that there isn’t a teapot in space orbiting between Earth and Mars, therefore it exists.” Reply: “No, I can’t prove the non-existence of the celestial teapot; but that doesn’t imply that it exists. It also doesn’t imply that there is even a good reason to believe it might exist.”

7. © Colin Frayn, 2008 www.frayn.net Extrapolations Seeing how a trend is moving today, and assuming that it can be followed forwards or backwards in time without changing. Example: “There are 6 billion people alive today; but one century ago there were only 3 billion people alive. If you follow that rate of geometric increase back, then the entire world was empty of human beings 6,000 years ago.” Reply: “Possibly, but you can’t follow that rate of increase back – it’s a rate that applies only to this current society in which we live today; It requires modern medicine, plenty of food, warmth and shelter etc. It also applies to a period in which, despite two world wars, the death rate due to conflict was vastly lower than it has ever been in the history of our species. And there are many other reasons why it doesn’t apply to earlier times.”