Many fallacies are perfectly sensible ways to reason in a messy, imperfect world. ad hominem - someone you know to receive large sums of money from cigarette m

Many fallacies are perfectly sensible ways to reason in a messy, imperfect world. ad hominem - someone you know to receive large sums of money from cigarette manufacturers gives you several plausible sounding reasons why cigarettes don't cause cancer. It's an adhominem to doubt his arguments based on your knowledge of how he's getting paid, but it's also sensible. argumentum ad populum - an argument isn't necessarily true just because lots of people believe it, but in the absence of you being able to work out the absolute truth from first principles, it's completely sensible to take into account what other people believe when you evaluate your options, or what people in your situation have typically believed (appeal to tradition) denying the antecedent - red sky in the morning implies shepherds should take warning. It's not true to say that just because there isn't red sky in the morning, then shepherds should assume the weather will be fine, but excluding one of the conditions in which shepherds need to be careful is weak evidence that shepherds will be fine. The old 'absence of evidence is not evidence of absence' one, although I didn't see it on this page. Actually it is. It is weak and incomplete evidence of absence, but in the right circumstances it can be perfectly reasonable to change your opinion on whether something is present or not based on a lack of evidence for it being present. In the real world, weak evidence is often the best we're going to get and we're often going to be in situations where thought shortcuts are necessary and valuable. Pointing out fallacies is usually poor argumentation. My pet peeve on this one is the 'burden of proof'. Normal human debate isn't a game with strict rules and a judge that awards points, and I'm not sure it'd be any better if it were. You engage in a debate with someone when you both want to change the other persons mind. If you didn't want to change their mind you shouldn't be debating with them. You're very unlikely to change their minds by telling them that the burden of proof is on them not you (much more likely to end up arguing about who really has the burden of proof, a fruitless and uninteresting topic).