What is Evidence?


Richard F. Taflinger

This page has been accessed times since 5 June 1996.

This is Part Two of a Four Part series on finding support for papers and speeches.

Sources of Information

Where to Find Evidence


Evidence is a piece of information that supports a conclusion. The classic example is from the law court: means, motive and opportunity. If the defendant had the means to commit the crime (say, owned a weapon to commit the murder), a motive or reason why he or she would want to commit the crime (would inherit $50,000,000 with the victim dead), and the opportunity to commit the crime (was alone with the victim when he died with the expectation of getting away undetected), and the evidence (there's that word again) proved the above, then it would be a reasonable conclusion that the defendant committed the crime. Of course, the court requires more evidence: for example, that the crime was committed with the weapon (which requires forensic and ballistic evidence), and that the defendant was the one that used the weapon beyond reasonable doubt. Nonetheless, the point is clear. For a conclusion to be acceptable as true, there must be evidence to support it.

It's too bad the above is so idealistic. In point of fact, most of what people believe is unsupported by evidence. Nevertheless, ideas are stronger when backed by information that your audience accepts. The section on research below will go into greater depth on this.

What can you use as evidence? As stated above, for some people it is sheer volume or force of personality: "if I say it (whatever "it" is) louder than anybody else, or with greater confidence or charisma, I must be correct." One needs only see the effect of the oratory of Hitler to see how well this approach can work. However, for those who do not aspire to demagoguery, evidence based on objectivity, evidence that even those who disagree with you must, if they are not bigots, agree with, must be found.

Examples and Illustrations

A strong type of evidence is examples. In an example you show precedents for what you say, that you are not making things up as you go along, but that what you are using as support for a conclusion is not a fantasy. If you can show how your conclusion is the result of, results in, or derives from certain facts or events that anyone, even those who disagree with your conclusions, can see or experience for themselves, then you have strong evidence that your conclusion is correct. For example, look through much of this paper: you will find it liberally sprinkled with actual occurrences in which I have applied the ideas I am presenting to you, and the results of those applications. Those anecdotes are examples, and I use them in support of the efficacy of the methods I am urging you to try. They are evidence that the methods are viable.

However, not all examples are true-life. Some are hypothetical, i.e., not anecdotes about actual occurrences, but fictional accounts of what might happen if the ideas presented were applied. Such examples are illustrations, showing what might or might not occur if the ideas are used or not used. They are more used to clarify a position or point, and are left to the reader or listener to carry out to verify their truthfulness or effectiveness. Nonetheless, illustrations are useful since, when supported by other evidence, they often do not need verification as to their effectiveness as evidence. They can simply stand as is.

Analogy and Comparison


An analogy is drawing comparisons between different factors in two dissimilar things to help illustrate or clarify one of the two. One of the two is usually chosen because it is basically understood by the audience, and thus the one that is not understood can be made clear.

For example, you can draw an analogy between football and war. Both deal with offense and defense, ground gaining to win the war, downs that are the equivalent of battles, have platoon systems, generals (coaches), officers (quarterbacks and defensive callers), soldiers (linemen), etc. Thus the audience can get a clear, if perhaps simplistic idea of war through the analogy.

There are, of course, problems with using analogies. First, when deciding on the analogy you must choose one in which the similarities far outweigh the differences. For example, an analogy between producing a theatrical play and football would be ridiculous, since there are virtually no similarities (the director might be considered the coach, but there is no offense or defense, linemen or backs, there is a set script while a football game never goes according to plan).

Second, be certain your audience knows the elements of your analogy. You could, of course, draw an analogy between football and war for Australians, but all you would do is confuse the hell out of them. They do indeed have football, but it is a game that bears very little resemblance to the game played in North America or Europe. If you mentioned quarterbacks, linemen, downs, first and ten, or huddles, they wouldn't know what you were talking about; they are not elements of their game of football. Their game of football more closely resembles a gang rumble than a war. Thus, be certain your audience knows what you're talking about.

Third, analogies cannot stand alone. They are a wonderful way of clarifying points, but they do not actually prove anything. If you use an analogy, you must back it up with other types of evidence that support the analogy as being valid.


Comparisons are much like analogies without the complexity. When making a comparison, show how one thing is like or not like something else. Comparisons are particularly useful when explaining to your audience a concept out of the ordinary or not clear by "common sense". The difference between waste generated by coal-fired versus nuclear plants is more clearly made by making a comparison between amounts of waste created in, say, a year. A 1000 megawatt nuclear plant creates one cubic yard (two wheelbarrow loads) of waste per year; a 1000 megawatt coal-fired power plant creates 5,256,000 tons (105,000 truckloads) of waste per year. (Note the two comparisons made: one between quantity (cubic yards vs. tons) and the other between wheelbarrow loads and truckloads.) This use of comparisons to make a piece of evidence clearer is extremely useful when dealing with unfamiliar or uncommon ideas.

The same caveats you must observe when doing analogies apply when doing comparisons: likenesses far outweigh differences, audience familiarity with one of the elements of the comparison, and they cannot stand alone.


There are many types of evidence: illustrations, statistics, testimony, analogies, comparisons. However, if you don't know where to find it, you can't use it.

Personal Experience

The first place to look, and one of the best, is your personal experience. After all, who knows better how to do something than someone who has done it successfully? If you can say and show, "This is how I did [whatever]," most would agree that is a way to do "whatever". For example, if you wish to tell your audience how to rig a model ship, you could begin by telling them what materials you use, such as the thread and tweezers, glue and pins. Then show them how to tie and stretch and attach the thread to the ship, explaining the techniques as you go. Once the audience sees what happens when you do it your way, they will agree you know what you're doing (assuming that you do) and they can do it that way too.


The second place to look for evidence, if you haven't done it yourself, is to watch someone else do it. In other words, observation: "I didn't do it myself, but I saw it done, and this is what he/she/it did." This approach is useful when you need to support a complex technique that you have not had to opportunity to do yourself. Operating a nuclear plant control room is something that few people have done, but you can observe it and then describe what you saw.


If, of course, you can't watch something happen, you can talk to someone who has. The interview is a major source of information to support any contention you may wish to make. There is always someone, somewhere, who knows something that would help you, and is willing to talk to you.

An interview places an onus on you, as the interviewer, that you must not overlook. Many people are willing to talk to you, but not to teach you how to understand what they are saying. In other words, do your homework. If you wish information on nuclear power, know what questions to ask and have the vocabulary to understand the answers. If you have to ask what an atom is, or how to generate nuclear power, then you don't have the necessary background. You will also quite probably try the patience of your interviewee. Remember the purpose of an interview is to get fresh information, insight and proof unavailable from other sources, not background.


Of course, background is absolutely vital not only to understand but to communicate that understanding to others. Personal experience and observation are excellent sources of background, but no one can experience everything. Thus it is always a goo d idea to look in other places for background.


What many people seem to think is the only place to look for information is in books. Don't get me wrong: books are excellent. If I didn't think so, I wouldn't write them myself. However, what you must always keep in mind is that any book, the moment it hits the shelf, is out of date. It takes anywhere from six months to five or more years to write a book. After it's written it takes up to two years to get it published and on the shelf. Thus, particularly in some areas such as electronics, cybernetics, math, physics, and other aspects of science and engineering, even the most current research appearing in a book can be at best incomplete and at worst totally wrong.

If the book is old, the problem is even worse. After all, if you based your ideas on a book written at the turn of the century, you could end up telling your audience that the sun is a huge ball of burning coal that would burn out in a few thousand years. The nuclear process of mass into energy, which powers the sun, was unknown much less understood before 1905 and Albert Einstein. Thus, always check the copyright date -- if it's more than a few years old, see if you can find something more current.

A second problem is that many people find one book and base all their evidence on it. However, authors write books to express their ideas and interpretation of whatever, if any, evidence the author has found to support them. A problem is that authors can be misled, misapprehend, not do enough research, or even deliberately set out to mislead their readers. If you don't believe the latter is possible, remember Hitler and Mao and . . .. This, considering that the information in books can become outdated, requires the careful researcher to look in more than one, or two, or three to check each one against the other.

Let me give you an example from my own research. I was to determine whether or not there was a raised stage in the 5th and 4th century B.C. Attic Greek theatre. I was certain there was indeed a stage, and set out to prove it. However, believing that no one source can tell me all nor be trusted as the only way to view any subject, I not only read those books that agreed with me but those that didn't. Then I checked the sources the authors had used, then checked those as far back and as well as I could. From this cross checking, and other research, I found that I was wrong, that those books that said there was a stage hadn't fully understood the evidence. I decided there was not a raised stage in the Attic Greek theatre. At least that is my opinion based on my research: there are many who, from their research, disagree with me. Fine: there is more than one way to view just about anything. However, if you were writing or speaking on the topic and only read what they wrote about it, you would be wrong. You would be as wrong if you read only what I wrote. You must read both and form your own opinion. Compare the evidence presented on all sides and weigh them without prejudice against everything else you find. No one is the final word on anything. Only you can be the final word for yourself.


If books are not the final word, where else can you look? Another fine source of information is journals. People often ignore journals because they are magazines written for specialists in a particular field. This is both their strength and their weakness.

Almost any field you can think of has one or more journals. Medicine has THE NEW ENGLAND JOURNAL OF MEDICINE or THE LANCET. Theatre has THE SHAKESPEARE QUARTERLY and THE TULANE DRAMA REVIEW. Biology has the QUARTERLY REVIEW OF BIOLOGY. Veterinarians have the VETERINARY RECORD.

The strength of journals is that leading specialists in the fields write the articles in them, sharing their latest research and insights. Thus you get the thinking of the leading people to support your ideas. The weakness of journals is that leading specialists in the field write the articles in them (sound familiar?). The specialists do not write the articles for the average person to understand but for other specialists to understand. Thus the language, syntax, vocabulary, etc. may approach opaque for a nonspecialist. Here are some examples of how confusing it can be:

One of the remarkable and characteristic properties currently under intensive laboratory study is that when a metallic receptacle is subjected to a careful and continuous scrutiny of a deliberate nature, the mixture which it is the nature and purpose of the said receptacle to contain will not, in point of fact, undergo a phase change and permit entry into a gaseous form at any point in time within the duration of the aforementioned scrutiny.

Meaning: A watched pot never boils

We have found that the individual under study should find the most feasible means that will enable him or her, as the case may be, to enter into a rapid repose, facilitating, as soon as possible, an actual somnolent condition along an interface as well as a precocious cessation of the condition and re-entry into a scheduled plan of activities that will maximize salubrious and/or salutary conditions, in addition to factors which favor a rise in profits or, as the circumstances may dictate, greater growth in the level of mental performance and achievement.

Meaning: Early to bed and early to rise . . .

Here is an example from the QUARTERLY REVIEW OF BIOLOGY.

A change elicited by an affect or effect or by an effectant in the affectee is a passive or active response affect or response effect. If it counters the affect or effect of the affectant which elicits it, is an active counter-affect or counter-effect. If it is an active counter affect or effect, it is a counter active affect or effect, i.e., a reaction in the strictest sense of the term as used by pathologists.

I wish you luck with this one. I haven't provided a translation because I can't figure out what it says.

Nevertheless, don't let the above extreme examples frighten you away from using journals. They are still an excellent source of information.

Journals have one other problem. Publishers issue them at long intervals, varying from three months to a year. The articles are therefore four or five months to two years removed from the end of the research the author has done. Thus, although not as out-of-date as books must be, they are still not the latest word.


Where else can you go, then? The answer is magazines. Publishers issue magazines every month or even every week. The information in the articles is therefore quite fresh, perhaps only one or two months old.

There is, of course, a problem with magazine articles as a source of information. Unlike books or journals, reporters, not specialists in the field, write the articles. They are not actually doing the research to generate the article, but are reporting what the specialists are doing. Many magazines employ reporters with qualifications in the area they are reporting. A science reporter for TIME magazine may write about anything having to do with science. However, he/she cannot be an expert in rocketry, biology, astronomy, and all the other areas of science he or she might cover.

Nonetheless, as a source of current background information, magazines are invaluable.


To get the latest information available, the place to look is in newspapers. Their information is from yesterday. However, the problem of reporters writing the articles as explained above is exacerbated by three things. First, the reporter is even less likely to be an expert on the subject. Editors often assign a story to a reporter because he/she is available, not because of any particular qualifications in the area. It is true that newspapers reporters are expert at gathering information through observation, interviews and background research. However, they are not always experts in the fields they are covering.

Second, newspapers reporters are always under the gun of a deadline. They often must write the article within a very short time. They thus may have to take shortcuts or forego more in-depth analysis or research to finish on time. Thus the article may not be as informative or reliable as other forms of research.

Third, the writing style of newspapers is different from that of books, journals or magazines. The inverted pyramid style works well to help you decide if you want to read the article. Its opening paragraph contains the basics of the entire story and following paragraphs go into greater and greater detail. However, you can lose some of the organization necessary to see the relative importance of various points. In addition, the editor, due to space restrictions, may cut paragraphs off the end of the article. These paragraphs may contain just the details you need.

Feature stories, those written less to report the news than to provide the newspaper's readers with information on a topic, don't have all of the above drawbacks. The reporter who writes the story is often given the assignment due to some expertise in the area; since there is no great rush to put the story before the public, the onus of the deadline is reduced; and finally, the feature story does not have to use the inverted pyramid style but can be written in expository style.

Nevertheless, don't disparage what you can find in newspapers. They are an excellent source of background information and leads to other places to look for support.

The Internet

Finally, there is the Internet, the World Wide Web. Obviously, it is a source of information: if it wasn't, what are you doing reading this? It is possible to get, in your home, articles, information, books, opinions, etc., etc., ad nauseam, from millions of people. However, everything should be taken with a grain of salt (including this!). The net is loaded with everything from the top experts in their fields to the paranoid ramblings of idiots (no comments!). Check out the credentials of those you cite. But use the net -- it contains things that you won't or can't find elsewhere, and is often as up-to-date as the daily newspaper. For those of you in media, I suggest:

Go to Part Three: The Problems with Statistics

Go to Part Four: The Process of Research

Return to Part One

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