|Many of the important points of this section are covered in the section on writing Argumentative Essays: Being Logical. You might want to review that section first and then come back here for a more thorough review of the principles of logic.|
|This document is part of a collection of instructional materials used in the Purdue University Writing Lab. The on-line version is part of OWL (On-line Writing Lab), a project of the Purdue University Writing Lab, funded by the School of Liberal Arts at Purdue.|
We use logic every day to figure out test questions, plan our budgets, and decide who to date. We borrow from the vocabulary of logic when we say, "Brilliant deduction" or even "I don't want to argue about it." In the study of logic, however, each of these terms has a specific definition, and we must be clear on these if we are to communicate.
- Proposition --
- T or F in an argument, but not alone. Can be a premise or conclusion. Is not equal to a sentence.
- Premise --
- Proposition used as evidence in an argument.
- Conclusion --
- Proposition used as a thesis in an argument.
- Argument --
- A group of propositions of which one is claimed to follow from the others.
- Induction --
- A process through which the premises provide some basis for the conclusion
- Deduction --
- A process through which the premises provide conclusive proof for the conclusion.
|Argument Indicators:||Premise Indicators:||Conclusion Indicators:|
When dealing with persuasive writing, it will be helpful for you to outline the argument by premises and conclusions. By looking at the structure of the argument, it is easy to spot logical error.
"Universities are full of knowledge. The freshmen bring a little in, and the seniors take none away, and knowledge accumulates.
-- Harvard President A. L. Lowell
|Freshmen bring a little (knowledge) in|
Seniors take none away
Universities are full of knowledge
(Here, the conclusion of one argument is used as a premise in another. This is very common.)
Even though there may be a deceiver of some sort, very powerful and very tricky, who bends all his efforts to keep me perpetually deceived, there can be no slightest doubt that I exist, since he deceives me; and let him deceive me as much as he will, he can never make me be nothing as long as I think I am something. Thus, after having thought well on this matter, and after examining all things with care, I must finally conclude and maintain that this proposition: I am, I exist, is necessarily true every time that I pronounce it or conceive it in my mind.
-- Rene Descartes, *Meditations*
|Argument 1 Premise 1:|
Conclusion of Argument 1
|To be deceived ... I must exist |
When I think that I exist I cannot be
I am, I exist, is necessarily true ... .
Find the Arguments and Outline them in These Statements:
1. Ask the same for me, for friends should have all things in common.
-- Plato, Phaedrus
2. Matter is activity, and therefore a body is where it acts; and because every particle of matter acts all over the universe, every body is everywhere.
-- Collingwood, The Idea of Nature
3. The citizen who so values his "independence" that he will not enroll in a political party is really forfeiting independence, because he abandons a share in decision©making at the primary level: the choice of the candidate.
-- Felknor, Dirty Politics
Reaching Logical Conclusions
This article is reprinted from pages 78-79 of Pearson-Allen: Modern Algebra , Book One. In the book it is one of several between-chapter articles that add interest and provike thought on subjects related to the topics discussed in the text.
Consider the two statements:
1. Any member of a varsity squad is excused from physical education.
2. Henry is a member of the varsity football squad.
Our common sense tells us that if we accept these two statement as true, then we must accept the following third statement as true:
3. Henry is excused from physical education.
We say that the third statement follows logically from the other two.
In drawing logical conclusions it does not matter whether the statements we accept as true are reasonable or sensible. This is because we depend entirely upon the form of the statements and not upon what we are talking about. Thus, if we accept the following statements as true:
1. All whales are mammals;
2. All mammals are warm-blooded animals;
3. All warm-blooded animals are subject to colds;
then we must conclude that
4. All whales are subject to colds. Do you see that statements 1, 2, and 3 are arranged in logical order ?
|In the diagram at the right the set of whales is represented|
by W, the set of mammals by M, the set of warm-blooded
animals by B, the set of animals by B, the set of animals
subject to colds by C, and the set of all animals by A. The
diagram shows that W is a subset of M as required by
statement 1, that M is a subset of B as required by statement
2, and that B is a subset of C as required by statement 3. The
only conclusion that uses all of our given statements is that
W is a subset of C, as asserted by statement 4.
|Had our third statement been "no warm-blooded animals are subject to colds," our diagram would have been the one shown at the right and our conclusion would have been "no whales are subject to colds."|
If you have read Alice's Adventures in Wonderland or Through the Looking-Glass , you know that their author, Lewis Carroll, delighted in giving sets of nonsense statements which lead to logical conclusions. One such set is the following:
- Babies are illogical;
- Nobody is despised who can manage a crocodile;
- Illogical persons are despised.
When these statements are arranged in logical order we have:
1. Babies are illogical;
2. Illogical persons are despised;
3. Nobody is despised who can manage a crocodile.
From these we can draw the logical conclusion:
4. Babies cannot manage crocodiles.
Other sets of statements written by this author follow. To draw a conclusion from each set of statements, first arrange the statements in logical order. A diagram such as those in the preceding column may help you. The correct conclusions are given at the bottom of the page, but do not look at them until you have written your conclusion.
1. Everyone who is sane can do Logic;
2. No lunatics are fit to serve on a jury;
3. None of your sons can do Logic.
1. No ducks waltz;
2. No officers ever decline to waltz;
3. All my poultry are ducks.
1. No kitten that loves fish is unteachable;
2. No kitten without a tail will play with a gorilla;
3. Kittens with whiskers always love fish;
4. No teachable kitten has green eyes;
5. No kittens have tails unless they have whiskers.
1. There is no box of mine here that I dare open;
2. My writing-desk is a box made of rose-wood;
3. All my boxes are painted except what are here;
4. There is no box of mine that I dare not open, unless
it is full of live scorpions;
5. All my rose-wood boxes are unpainted.
I. None of your sons are fit to serve on the jury.
II. My poultry are not officers.
III. No kitten with green eyes will play with a gorilla.
IV. My writing-desk is full of live scorpions.
With this brief introduction to Lewis Carroll type problems, you will find it worthwhile and interesting to construct your own problems of this type.
(The fun part)
A fallacy is an error of reasoning. It can be used against you in an argument, but if you are familiar with them, you will be able to refute the fallacious argument. Likewise, if you are clever, you can use them to convince others.
Fallacies fall into two major categories:
- Fallacies of Relevance
- -- Premises are irrelevant to the conclusion.
- Fallacies of Ambiguity
- -- Ambiguous, changeable wording in the propositions
Here are examples of each of the major fallacies. You figure out and write in a definition which makes sense to you.
Fallacies of Relevance
- 1. Argumentum ad Bacculum (appeal to force) --
- "Pay back the loan and 10 % daily interest by Thursday, or be sure that you have you hospital insurance paid up."
- 2. Argumentum ad Hominem (abusive) --
- "Don't believe anything John says; he's a nerd."
- 3. Argumentum ad Hominem (circumstantial) -- "Of course he thinks fraternities are great. He's a Phi Delta."
- 4. Argumentum ad Ignorantiam (argument from ignorance) --
- There is no proof that witches exist; therefore, they do not.
- 5. Argumentum ad Misericordiam (appeal to pity) --
- "Your honor, how can the prosecution dare try to send this poor, defenseless child to jail for the murder of his father and mother. Have a heart; the boy is now an orphan."
- 6. Argumentum ad Populum --
- "Don't be left out! Buy your Chevette today!"
- 7. Argumentum ad Vericundiam (appeal to authority) --
- Joe Namath selling pantyhose; Joe DiMaggio selling Mr. Coffee.
- 8. Accident --
- "What you bought yesterday, you eat today; you bought raw meat yesterday; therefore, you eat raw meat today."
- 9. Converse Accident (hasty generalization) --
- "That man is an alcoholic. Liquor should be banned."
- 10. False cause (Post hoc ergo propter hoc) (Many of our superstitions stem from use of this fallacy.) --
- "a black cat crossed Joe's path yesterday, and he died last night." or "Put your money where your mouth is. Whiter teeth and fresh breath will win Susie."
- 11. Petitio Principii (begging the question) --
- "It's time to come in the house now, Billy."
"Because I said so!"
"Because it's time, and I said so."
- 12. Complex Question --
- "Have you given up cheating on exams?"
- 13. Ignoratio Elenchi (irrelevant conclusion) --
- In a law court, in attempt to prove that the accused is guilty of theft, the prosecution may argue that theft is a horrible crime for anyone to commit.
Fallacies of Ambiguity
- 1. Equivocation --
- Some dogs have fuzzy ears. My dog has fuzzy ears. My dog is some dog!
- 2. Amphibole (grammatical construction) --
- "Woman without her man would be lost." or "Save Soap and Waste Paper."
- 3. Accent --
- "We should not speak ill of our friends."
- 4. Composition--
- "Each part of this stereo weighs under one pound. This is a very light stereo."
or " ... ONLY $1.97 plus processing and postage."
- 5. Division--
- "Purdue is a great engineering school. Mike went there; he must be a great engineer."
Listen to your roommate, the T.V., and even your profs. You'll be amazed how many fallacies we encounter each day.
More important, check your papers. Does your argument have premisses and conclusions stated properly? Have you been guilty of fallacious reasoning?
(from Copi, Introduction to Logic pp. 85-87)
Identify the Fallacies in the Following Passages and Explain how each Specific Passage Involves that Fallacy or Fallacies:
1. It is necessary to confine criminals and to lock up dangerous lunatics. Therefore there is nothing wrong with depriving people of their liberties.
2. How much longer are you going to waste your time in school when you might be doing a man's work in the world, and contributing to society? If you had any sense of social responsibility, you would leave immediately.
3. The army is notoriously inefficient, so we cannot expect Major Smith to do an efficient job.
4. God exists because the Bible tells us so, and we know that what the Bible tells us must be true because it is the revealed word of God.
5. Congress shouldn't bother to consult the Joint Chiefs-of-Staff about the military appropriations. As members of the armed forces, they will naturally want as much money for military purposes as they think they can get.
6. Mr. Brown: I will give no more money to your cause next year.
Solicitor: That's all right, sir, we'll just put you down for the same amount that you gave this year.
7. When we had got to this point in the argument, and every one saw that the definition of justice had been completely upset, Thrasymachus, instead of replying to me, said:
"Tell me, Socrates, have you got a nurse?"
"Why do you ask such a question," I said, "when you ought rather to be answering?"
"Because she leaves you to snivel, and never wipes your nose: she has not even taught you to know the shepherd from the sheep."
-- Plato, Republic
8. Narcotics are habit-forming. Therefore if you allow your physician to ease your pain with an opiate, you will become a hopeless drug addict.
9. You can't prove that he was to blame for the misfortune, so it must actually have been someone else who was responsible.
10. You can't park here. I don't care what the sign says. If you don't drive on, I'll give you a ticket.
11. But lest you think, that my piety has here got the better of my philosophy, I shall support my opinion, if it needs my support, by a very great authority. I might cite all the divines almost, from the foundation of Christianity, who have ever treated of this or any other theological subjects: but I shall confine myself, at present, to one equally celebrated for piety and philosophy. It is Father Malebranche...
-- David Hume, Dialogues Concerning Natural Religion
(from Copi, *Introduction to Logic* pp. 87-88)
16. Cooks have been preparing food for generations, so our cook must be a real expert.
17. More young people are attending high schools and colleges than ever before in the history of our nation. But there is more juvenile delinquency than ever before. This makes it clear that to eliminate delinquency among the youth we must abolish the schools.
18. You say we ought to discuss whether or not to buy a new car now. All right, I agree. Let's discuss the matter. Which should we get, a Ford or a Chevy?
19. Our nation is a democracy and dedicated to the proposition that all men are created equal. We believe in equality of opportunity for everyone, so our colleges and universities should admit every applicant, regardless of his economic or educational background.
20. Anyone who deliberately strikes another person should be punished. Therefore the middleweight boxing champion should be severely punished, for he assaults all of his opponents.
21. We should reject Mr. Watkins' suggestions for increasing the efficiency of our colleges. As a manufacturer he cannot be expected to realize that our aim is to educate the youth, not to make a profit. His recommendations can have no value for us.
22. Everyone said that the soup had a very distinctive taste, so they must all have found it very tasty.
23. If we want to know whether a state is brave we must look at its army, not because the soldiers are the only brave people in the community, but because it is only through their conduct that the courage or cowardice of the community can be manifested.
-- R. L. Nettleship, Lectures on the Republic of Plato
24. My client is the sole support of his aged parents. If he is sent to prison, it will break their hearts, and they will be left homeless and penniless. You surely cannot find it in your hearts to reach any other verdict than "not guilty."
25. There is no proof that the secretary "leaked" the news to the papers, so she can't have done it.
26. Diamonds are seldom found in this country, so you must be careful not to mislay your engagement ring.
27. Was it through stupidity of through deliberate dishonesty that the Administration has hopelessly botched its foreign policy? In either case, unless you are in favor of stupidity or dishonesty, you should vote against the incumbents.
28. Since all men are mortal, the human race must some day come to an end.
Try these for Fun!
Exercises in Reasoning
I. Four men, whom we shall call Robert, Ralph, Ronald, and Rudolph, were playing cards one evening. As a result of a quarrel during the course of the game, one of these men shot and killed another. From the facts below determine the murder and the victim.
- Rudolph had known Ronald for only five days prior to the murder.
- Robert will not expose his brother's guilt.
- Rudolph has been released from jail on the day of the murder, after serving a three day sentence.
- Ralph met Robert's father only once.
- Robert had wheeled Ralph, a cripple, to the card game at Ronald's home.
- The host is about to give evidence against the murderer, whom he dislikes.
- The murdered man had eaten dinner on the previous evening with one of the men who did not customarily bowl with Ronald.
II. Five men are in a poker game: Brown, Perkins, Turner, Jones, and Reilly. Their brands of cigarettes are Luckies, Camels, Kools, Old Golds, and Chesterfields, but not necessarily in that order. At the beginning of the game, the number of cigarettes possessed by each player was 20, 15, 8, 6, and 3, but not necessarily in that order.
During the game, at a certain time when no one was smoking, the following obtained:
- Perkins asked for three cards.
- Reilly had smoked half of his original supply, or one less than Turner had smoked.
- The Chesterfield man originally had as many more, plus half as many more, plus 2 1/2 more cigarettes than he has now.
- The man who was drawing to an inside straight could taste only the menthol in his fifth cigarette, the last one he smoked.
- The man who smokes Luckies had smoked at least two more than anyone else, including Perkins.
- Brown drew as many aces as he originally had cigarettes.
- No one had smoked all his cigarettes.
- The Camel man asks Jones to pass Brown's matches.
How many cigarettes did each man have to begin with, and of what brand?
A functional impropriety is the use of a word as the wrong part of speech. The wrong meaning for a word can also be impropriety.
Mark improprieties in the following phrases and correct them in the blanks at the right. If you find none, write C in the blank. Example: (occupation) hazards -- occupational
1. reforming institution policies
2. percentaging students by grades
3. dead trees as inhabitants for birds
4. an initiate story about a young girl
5. a recurrence theme in literature
6. a wood chisel
7. a wood baseball bat
8. a frivolity conversation on the weather
9. a utopia hideaway of alpine villas
10. a utilize room complete with workbench
11. the unstabled chemical compounds
12. the unschooled labor force
13. the vandals who rapined Rome
14. an erupting volcano crevassing the hills
15. criticism writing which is often abstract
16. abstracted beyond understanding
17. classified as an absorbent
18. a handwriting letter
19. banjoed their way to the top ten
20. a meander stream
21. hoboing across the country
22. holidayed the time away
23. the redirective coming from the officer
24. grain-fed slaughter cattle
25. ivy tendoned to the walls
What is a Definition Essay?
A definition essay works to provide the nitty-gritty details about a word or concept. For example, in an art class, you may be asked to write a definition essay on Vermillion (a vivid reddish-orange color) or Cubism, a specific approach to creating art. A definition essay should always focus on a complex subject; simple subjects won’t provide enough details to adequately write an essay. While the subject may change, the structure of an essay remains the same. All definition essays should include an introduction, body paragraphs, and a conclusion.
Types of Definition Essays
Professors often assign definition essays towards the beginning of a class. The focus of this type of essay is to explore a specific concept. These concepts are often divided into one of three categories:
In this type of essay, the assignment explores how to fully define a difficult topic. By definition, an abstract concept is one that is vast and complicated. Examples of abstract concepts include liberty, ambition, love, hate, generosity, and pride. The focus of the essay should be to break down the concept into more manageable parts for the audience.
Definition essays that focus on a place tend to explore a specific type of place and how you as the writer view this particular place. Types of places which may be assigned are a country, state, city, neighborhood, park, house, or a room. The place may be huge or small. A key to writing a good definition essay focused on the place is to select a specific place you are familiar with; it shouldn’t be a place you need to research — it should be a place that you know intimately.An Adjective
An adjective essay focuses on creating a definition for an adjective. Common topics may include describing a “good” or “bad” friend, present, or law. The focus of the essay should explore the qualities and characteristics of a good friend or a bad present.
Perfecting the Definition Essay Outline – and Beyond!
Before sitting down to write a definition essay, you’ll need to make out all the parts to the whole. In other words, how, exactly, will you define the subject of the essay? You’ll need to consider all the different parts, or the gears, that make the clock work. Once you’ve brainstormed the parts, you’re ready to create an outline, and then write some paragraphs. The outline for this essay is as easy as in five paragraph essay – it contains an introduction, body paragraphs, and a conclusion. The number of body paragraphs is determined by how many aspects you’re subject needs defined. This type of essay is exactly what it sounds like: it works to define a specific word or concept.
Take Richard Brinsley Sheridan’s advice when writing: “Never say more than is necessary.”
So, here is what constitutes the outline of the definition essay:
An introduction paragraph should act as a gateway to the subject of the definition essay. Use this paragraph to gently introduce the subject, and gain the reader’s interest. This paragraph should begin with an attention getter (the “hook”) that makes the reader curious and want to read more. Quotations are always a great idea as are interesting facts. Next, provide background details that the reader will need to understand the concept or idea to be defined in the body paragraphs.
Unlike other papers, like cause and effect essay, the definition essay is unique in that it requires the writer to provide the dictionary definition of the word, and then the thesis definition. Since dictionary definitions are often dry and narrow, the thesis definition is your opportunity truly encompass the complexity of the word.
Each body paragraph should focus on a different aspect that contributes to the overall definition of the subject being discussed in the definition essay.
A definition essay typically contains three body paragraphs, although there can be more if the writer desires. The first body paragraph delves into the origin of the word and how it became mainstreamed into the language. This paragraph can talk about any root words, prefixes, and/or suffixes in the word, as well as the evolution of the word (if there is one).
- The Denotative Definition Paragraph
The second body paragraph should focus on the dictionary definition, and how the word can be used in writing and conversation. For example, love can appear as several different parts of speech; it can be a noun, verb, or adjective.
- The Connotative Definition Paragraph
The third body paragraph, and often the longest one, should focus on conveying the writer’s definition of the word. This definition should be based on both the writer’s personal experience as well as research. Don’t be afraid to be bold – describe this word in a way that no one else has! Be original; describe the word as a color or animal, and defend your choice. Provide examples of the word in action and maintain the reader’s engagement at all costs. Aim for sentences like this:
Quixotic describes the eternal quest of optimistic individuals striving to find the magical, the visionary, the idealistic experiences in life despite all obstacles and naysayers.
This exists as an excellent sentence because it provides clues as to the type of word quixotic is by pairing it with magical, visionary, and idealistic. By stating that it’s a word optimistic individuals would gravitate towards, the audience inherently understands it’s more positive than negative. Indeed, the third body paragraph should focus on communicating the writer’s comprehension of the concept, idea or term.
Just because this is the shortest paragraph, doesn’t mean that it will be the easiest to write. In fact, the better the body paragraphs are, the easier writing the conclusion paragraph will be. Why? Because a good conclusion paragraph reiterates the main points stated in each body paragraph. If the body paragraphs are clear and avoid rambling, pulling the main ideas for the conclusion will be easy! Just remember: you don’t want to repeat yourself word for word, but you do want to echo your main ideas; so summarize yourself instead of copy and pasting.
Many professors may create the definition essay as a personal writing assignment. If this is the case, then it would be appropriate to also discuss what the word or concept means personally to you. Select an example in your own life and validate your descriptions of the word.
“I need someone to write my essay!” – That’s something we hear a lot. The good news is that you are in the right place to find help. HandMadeWritings is the best essay writing service on the web.
Definition Essay Outline Example
Once you got the concept of your future essay wrapped up, it’s time to put things to the practice and create an outline. Here is what your outline might look like. Our topic is: Love.
- Introduction. Thesis: While different cultures define the concept of love differently, most cultures will agree that love exists as a positive, yet broad concept that has fueled humans since the dawn of time.
- Topic Sentence 1. While the Ancient Greeks, Chinese, and Persian cultures all approached love differently, they also shared many similar attitudes towards love.
- Topic Sentence 2. The denotative definition of love includes 7 noun definitions and 6 verb definitions; this highlights the complex nature of love as a concept.
- Topic Sentence 3. Modern society is fueled by the idea of love whether in intrapersonal, interpersonal, or business relationships.
- Conclusion. Love affects every aspect of the human experience and has since the beginning of time.
Definition Essay Sample
Be sure to check the sample essay, completed by our writers. Use it as an example to write your own argumentative essay. Link: Essay sample: Team Norms and Procedures.
Tips on Writing a Definition Essay from Our Experts
Need some advice from our professional writers? We’ve got you covered. Here are some great tips on how to write an A-level definition essay:
- When writing a definition essay, keep the sentences simple when you can; however, occasionally, you’ll need to create longer, more descriptive sentences. Consider juxtaposing short sentences with longer ones to maintain reader interest.
- Incorporate literary devices when trying to define an abstract word or concept. Check out this example: Love is a campfire on a chilly November evening. Its warmth glides over your entire being, from the top of your head to the tips of your toes – but watch out: get too close, and you’ll catch fire and burn.
- Stuck on deciding on a topic? If you get to select your own topic, remember that selecting an abstract topic is best: love, forgiveness, contentment, or hero are all great options. Don’t fall into the trap of selecting a topic with too many aspects to define such as the history of man.
- Select a topic that allows plenty of original description – that’s the goal: to describe a concept in such a way that hasn’t been done before. Be original: state the history and the original of the word and then delve into your perception of it.
- Finally, begin early. Create an outline to help organize your idea, and then begin the research process to determine the origin of the word as well its evolution. Consider answering such questions as who created the word (Did you know Shakespeare coined the words lonely and majestic?), how it has evolved, and whether it has multiple parts of speech. The more questions you answer, the more definition will be put into your essay!