Critical thinkers should be on their guard against poor or invalid reasoning. In many cases arguments which appear to be the result of sound reasoning are in fact unsound because they contain an identifiable mistake. In this article we identify some common errors.
Errors relating to causation
Two things may be closely correlated in space or time without one of them being the cause of the other. In some cases it is simply unlikely that there is a causal relationship. Could hot weather cause a ship to sink? In other cases it is clear that a third factor caused them both e.g. rich people often have both big houses and expensive cars. Sometimes two things are interconnected so that they affect, but do not cause, each other e.g. price inflation and unemployment. And sometimes two things have coincided purely by chance. Problems over causation illustrate the need for a particular critical thinking skill – that we should not jump to conclusions.
Invalid testimony
We are all influenced by the things that happen to us, but our own experiences rarely have universal validity. Someone’s belief that their illness was cured by prayer is merely anecdotal evidence of little value to others. The same is true of intense religious experiences. Someone who has such an experience may find it profoundly moving, but other people have no good reason to take this as being evidence for any particular belief – such as the existence of God. It is not rational to be greatly influenced by another person’s private experience.
Dogmatism
Wise people learn that most of our beliefs are uncertain to some extent. However, many people do not have sufficient respect for evidence and argument. They make claims which are unjustified while insisting that their claims are true and must not be questioned. Dogmatists often make two other mistakes – that in a complex situation there are only two possible explanations or options, and that something they find unbelievable is actually impossible, for example that someone could run 100 miles in less than 24 hours.
Dogmatists often have difficulty understanding the nature of proof. They fail to grasp that claims require justification, and that it is for the person who makes the claim to provide the proof e.g. that there is a God. And yet they tend to demand an unreasonable degree of proof themselves, claiming that something is true unless proven false e.g. that Jesus rose from the dead, or that something is false until proven true beyond all possible doubt e.g. the theory of evolution. These are all mistakes which critical thinkers should try to avoid.
Common fallacies
Many arguments fall prey to simple fallacies. Here are some of the more common ones:
- ‘Ad hominem’ – attacking a person making an argument rather than addressing the argument itself
- Faulty direction – focusing on an irrelevant fact e.g. rejecting a doctor’s advice about weight gain merely because the doctor is overweight
- Circular reasoning – e.g. someone says, “I know the bible is the word of God because the bible says so”
- Begging the question – putting the conclusion of an argument into the premises so that nothing is proven e.g. quitting your job is the right thing to do because it is the proper option in this situation
- Appealing to an incompetent authority e.g. Einstein disliked ice-cream so no one should eat ice-cream
- Slippery slope – doing one thing will inevitably result in people doing some other thing
- Faulty division – claiming that whatever is true of the whole is true of the parts e.g. Manchester United is a great team so all the team members are great players
- Faulty analogy – suggesting that two things resemble each other when they don’t e.g. cold beer is as bad as cold coffee
- Appeal to nature – saying that we should not do things that are ‘unnatural’. Weeding crops is ‘unnatural’ but not wrong
- Appeal to authority – ‘The President said it so it must be true’
- Appeal to tradition – saying we should continue to do what we have always done
- Appeal to popularity – claiming that whatever most people believe must be true
- Red herring – offering something irrelevant to distract attention from the real issue
Being a critical thinker is not easy!disbelief, fostering dialogue and curiosity.