Skeptics have pretty good antenna in areas like the paranormal, 'alternative' medicine, bad science and dodgy journalism. Scientific methodology and the vocabulary of doubt come easily.
But when it comes to other areas that are not obviously in the skeptic domain, the radar can fail and we can be as irrational and gullible as someone who believes their great aunt is talking to them from Beyond The Veil. There are areas where the appliance of science fails us.
It's not just true believers who allow faith and hope to triumph over reason. We are all more gullible than we like to admit and we all have blind spots. I will be the first to admit to this; I really do believe that one day I will find a mascara that will make my lashes five times thicker. And I'm a sucker for adverts about new brands of crisps.
We could all benefit from turning our skeptical eye inwards sometimes.
Skeptics buy shoes that are lovely but not quite the right size, consigning ourselves to months of plasters and the possibility of seriously lumpy feet. Skeptics really really need that huge screen TV when the money would be better spent at the dentist. We hope against all reason that our team will win or believe that we'll find a parking space in the middle of town on a Saturday night. How many times has the mother of all hangovers made us swear never to drink again? Is any of this rational, evidence-based behaviour?
We may laugh at adverts that say 'Pay attention, here comes the science' but we all buy body products. It's not just women whose rationality fails here - how many blades does a razor need?Are we loyal to our toothpaste brand because our double-blind, randomised, placebo-controlled, peer-reviewed testing has proved it to be the best, because our mum used to buy it or because it's on offer? It's only toothpaste, after all. We may do comparison shopping for expensive things but for cheaper ones, convenience and habit often rule.
Technology is another area where rationality may fail. In some cases it fills a need, in others fashion and marketing create a 'need' and then feed it. Some upgrades improve functionality, some products improve efficiency or quality of life - and some do nothing more than run up the overdraft or stop you feeling old and left behind. It's technology, it's the future, look how shiny it is.
Then there is dieting. Skeptical methods may tell us that Atkins does not work and may well do harm but how many of us have failed to lose weight or put it back on again? We know how to lose weight, we know the science - calories in versus calories out - but reason fails in the face of pizza, beer and yes, crisps. And of course, some of us smoke.
How many good skeptics who are the first to spot confirmation bias or the ideomotor effect join a gym only to stop going after a couple of months while the cross-trainers we spent too much on get worn down the pub? The average monthly spend on a gym is £41. 95 and most gyms tie members in for a year. Some research shows that 80% of people stop going regularly - but are still paying - within eight weeks. Joining a gym is often an act of blind faith. The money could be better spent on other things - like shoes. Oh, and justify it any way you want, Wii is not exercise.
But it's when it comes to other people we're most likely to wander from the straight and narrow.
It's human nature to like people who are like us. There is good evolutionary sense in this, it bonds us to partners, kin and allies. We're much less likely to disbelieve or think badly of someone we like than someone we don't, even though common sense says this is nonsense. We cut friends more slack, ignoring or excusing flaws in people we love that drive us mad in others. Until the flaws start to really annoy us and we wonder how we ever found them charming. Or we wonder why they don't find our little habits so cute any more.
Instinct puts blinkers on everyone; a skeptic in love is no more rational than a true believer. The stats about how many marriages fail, how many people cheat and the costs of child support are bandied about in the media. But we hope, we have faith it will be different for us and we believe that this time we have chosen well because not to is to be cynical and alone. No one wants that and no one wants to take a step back and analyse someone's pros and cons before getting involved. Even if we did want to, instinct (or lust) would foil us.
Everyone succumbs to flattery sometimes, becoming willing accomplices in our own deception, wanting to be told that our bums don't look big in this, that the bald patch doesn't show or that size doesn't matter. Women pad their bras and buy magic knickers. Men put on a black T shirt, look in the mirror, suck in the gut and pat themselves on the back.
It's human nature; being completely rational and skeptical all the time is not possible - or even desirable. If we were, life would be pretty dull and predictable. Even Mr Spock couldn't be 100% logical and Data wanted an emotion chip so he could be a real boy.
We're all human, we all make mistakes, we all get fooled and fool ourselves. Nor should it be any other way, even if we do try to minimise the failures. Remember that Bible quote about motes and beams?
UPDATE: Some people are misreading this as excusing beliefs in the supernatural or 'alternative' medicine. Or that I'm saying all mistaken perceptions are equal so we should just shut up.
To spell it out for them: try to see people as individuals, not as targets or sets of behaviours and beliefs to be corrected. You can't explain the facts to someone if you've already alienated them. A little empathy goes a long way.
Most people, on the other hand, got that first time through.