Seven Types of EvidenceIt is important to learn to use

Seven Types of Evidence
    Good morning. Today we will talk about how to use evidence in writing. In much of your college writing, you will try to persuade your readers to see things in your way. Without good evidence to support your ideas, you will hardly persuade anyone of anything. So today we’ll look at seven kinds of evidence that are widely used in argumentative writing.
    The first type of evidence is expert testimony. An expert is someone who has special skill and knowledge based on careful study and wide experience in a certain area. More than that, an expert has tested his or her skill and knowledge in a public forum.
    Once your opinion is firm, you can use expert testimony to support it. To use expert testimony wisely, you need to be both respectful and critical. You will need to differentiate among (1) three kinds of evidence that experts provide: facts, informed opinions, and speculations. Generally, you can use facts and informed opinions, but must be cautious with speculations. This is because speculations are just what one person thinks is plausible, so they should be treated as something that could be true.
    The second type of evidence is statistics. Statistics are numerical data gathered and tabulated to yield information. Whether they are raw data or translated into charts and figures, numbers are powerful evidence. If they are properly used, data can prove a claim rapidly and conclusively. When a survey shows that 95 percent of senior students are satisfied with the courses they have taken at a university, we can persuade readers that the university is a good one.
    But you must be careful with numbers. (3) Only when the data are valid, accurate and up-to-date can they really support your point. So when you want to use data, examine carefully before putting them down in your article.
    Next comes the third evidence, examples. Every day you use examples as evidence for your claims. You might write to your parents, " Sorry I haven’t written much but I’ve been very busy. I spent last week in the library, bent over the books studying for two midterms. " In this case, you establish your claim and back it up with a specific example.
    Examples serve three purposes. First, they clarify meaning. Your parents may not know exactly what you mean by busy until you show them. Second, examples demonstrate why, at least in one instance, you are justified in making your claim. Studying for two midterms does sound like being busy. (4) Third, examples make for entertaining reading. Abstractions are dry. Claiming that you are busy isn’t very interesting. But the image of you bent intently over a book probably pleases your parents, who may now forgive you for not writing.
    The fourth type of evidence is personal experience. If we actually experience something directly, we don’t need experts or statistics to back us up. Although we know that our experience is not totally reliable, we trust our senses and our ability to understand our personal experience. And in some cases, our own experience can persuade readers to accept our statement.
    In complex matters, however, (5) be aware of jumping to conclusions based on limited personal experience. Your experience may help to explain, but it cannot prove a more general thesis. Knowing someone who cheats on her income tax does not prove that the problem with income tax cheaters is pervasive. Even if you know five or ten or twenty cheaters, all that proves is that you are unlucky in your acquaintances. For such a complex subject, you need more than personal experience. You need statistics and expert interpretation.
    Analogy is the fifth type of evidence on our list. An analogy is a comparison of apparently dissimilar things, and its purpose is to illuminate one thing by showing how it is like and not like the other. If well used, (6) an analogy can make an abstract, unfamiliar topic easy to understand. For example, if a writer wants to directly persuade readers that it is our work that determines our social role, he would face a tough task. But analogy can help him out. Here is his analogy;
    Human beings in a society are like the bees in a hive. Each person’s identity is determined by his or her place in the overall system. Like drones, no one has any identity but the work he or she does. And if one doesn’t work, he will be kicked out of the society just like a drone out of the hive.
However, analogies should be used with caution. To the extent that analogies make a point easy to see, they are evidence. But they don’t prove the point—they can never be sufficient evidence for a complex idea.
    After analogy, let’s look at the next type of evidence, known facts. (7) When writing. you can safely assume that you and your readers share a vast body of facts and beliefs. You don’t need to point out Columbus arrived in America in 1492, or that China has a history as long as 5, 000 years. But these facts can be used as evidence in your writing.
    The last type of evidence we usually use is logic and reasoning. In some cases, (8-1) we use them because we can’t find any other factual evidence. And in some cases where we can find factual evidence, (8-2) reasoning can make our argument more persuasive. People in China believe that good argument should appeal to both sense and sensibility, which means that both factual evidence and reasoning are necessary.
    OK, these are the seven types of evidence. Before we end today’s lecture, I would talk about three criteria for good evidence. First, good evidence should be relevant. It should speak directly to the point. You should select particular evidence because it supports the point, not because it is novel or comic. (9) Second, good evidence should be representative. It should represent its source or the situation it describes. (10) Last, good evidence should be accurate. It is the writer’s duty to ensure the accuracy of the evidence. In order to do this, you must check the evidence carefully, and present it in your writing carefully.
    Well, with that, we will end today’s lecture. We hope that you now understand evidence better, and we look forward to seeing well-supported articles from you in the future.