What is critical thinking and why is it important?

People often try to persuade us of things: the people who write editorials and letters to the editor, politicians, lecturers, advertisers, evangelists, your parents, your children, your friends. And when someone is trying to persuade you of something, you should think:  what reasons have I really been given for believing what this person wants me to believe? Are they good reasons? This is what we mean by critical thinking or critical reasoning.

You already do this to some extent, whether or not you know it.  Especially if you spend any time online, you are probably constantly being bombarded with information and arguments. You don’t believe everything you’re told and everything you read.  You can’t, in fact, because some of the various things you get told conflict with each other.   You are already somewhat selective about which of those things you accept – we are going to give you better tools with which to be selective.

One example of a situation in which critical thinking is required is being on a jury.

When you are on a jury, you are faced with a barrage of evidence in support of different conclusions, and you have to weigh it all up and come to an informed decision. The prosecuting lawyer is trying to convince you that the accused committed the crime; the defense attorney is trying to convince you that the prosecutor hasn’t proved her case, that at the very least there is doubt about whether the accused committed the crime.  And you have to decide what the right conclusion is.  Furthermore it matters a lot what you decide – the future of the accused person depends on it.  One of our aims (perhaps the main aim) is to make you better at the kind of critical thinking required in this kind of context –  better at evaluating what others say when they’re trying to convince you of something.

We also hope that learning to recognise the difference between good and bad reasons will make you better at convincing other people of things you want them to believe.  Sometimes you are the person who is trying to do the persuading. Perhaps you want to persuade people to vote for the political candidate you support or you’re the one trying to save their souls; or perhaps  you just have a strong urge to get other people to agree with you about the things you care about.  Learning to make a good, logical case will go some way towards making you more persuasive.  This is important in the jury example as well. After the jury has heard all the evidence, they retire to deliberate – to discuss the evidence and the law and come to a decision about whether or not the defendant should be found guilty. At that point, as well as being able to evaluate the reasons your fellow-jurors are putting forward, you will want to make a good job of putting forward your own view about whether the defendant is guilty and why. Perhaps most of your fellow-jurors think it is clear that the defendant committed the crime, but you think there are good reasons to doubt this. Being able to state those reasons clearly and straightforwardly may make a real difference to the outcome.

Note that we’re not trying to teach you rhetoric – how to use flowery or emotive language which helps you to persuade people of things even when you don’t really have a good case. Rather, we’re trying to teach you how to give people genuinely good reasons to believe what you want them to believe or to do what you want them to do. The main thing you need to know in order to do this AND in order to evaluate other people’s reasoning is what counts as a good reason  to believe something and what doesn’t.

Here’s a bit of rhetoric, just to illustrate what we’re NOT trying to teach you to do.

Would it be so terrible if there were no slaughterhouses filled with stinking bloody carcasses?  Would our lives be poorer if no animals writhed in steel-jaw leg hold traps?  Would we fare so badly by wearing natural fabrics instead of furs and leathers?  Who could object to a medical science that advanced prevention and healthy lifestyles instead of vivisecting living animals? 

This is all presentation and no content.  Phrases and words such as “stinking bloody carcasses” and “writhed” are highly emotive rather than strictly factual.  We are supposed to be swept along by the repetitive rhythm of the rhetorical questions.  We’re supposed to think that the obvious answers to them are “NO!”, “NO!”, “NO!” and “NO-ONE!”   But are we given any actual reason to think so?  None whatsoever.

We will not be teaching you to talk or write like that, although undoubtedly it’s a useful skill and one that those who are in the business of persuading others (for example advertisers, and politicians) would benefit from acquiring.  Learning to see through rhetorical flourishes, however, is part of what we hope you will get from working through this book. You should think: “Wait a minute!  What is this person trying to convince me of?  Have I actually been given any reason to believe the thing they are trying to convince me of?”

A further aim, as well as giving you the tools to evaluate other people’s reasoning and to produce good arguments yourself in order to persuade other people, is to encourage you to think critically about your own beliefs and the reasons you have (or perhaps don’t have!) for holding them. We all have lots of beliefs that we haven’t exactly thought through – we may have religious or moral beliefs as a result of our upbringing, for example, and never have thought about whether we actually have good reasons for them.

We will be focusing a lot on how to tell good reasoning from bad reasoning (and suggesting you should apply this both to other people’s reasoning and to your own). A secondary focus will be  how to construct chains of reasoning or arguments which are logical, and therefore more likely to convince people.  To some extent these two things go together – if you can tell good reasoning from bad, you’re more likely to be able to construct good, logical chains of reasoning yourself.

This book will help you to gain skills, or to further develop skills that you already have to some extent , rather than giving you a lot of factual information that you need to memorise. And the way to acquire skills is to practice them a lot. We will be providing you with exercises that you can work through, with feedback: doing these exercises, paying attention to the feedback, and then doing more exercises will help you to become a critical thinker.