Combined Comparison and Contrast

Occasionally, because you wish to achieve a close relationship to two constituent parts of a subject, you may decide to combine comparison and contrast in the same paragraph. If so, you can follow the procedures, suggested earlier, of putting the compared (or contrasted) materials in a single sentence, in alternate sentences, or in groupings of several sentences. Should you use the last of these methods, be sure to insert between the groupings, for the sake of good coherence, some word, phrase, or sentence, that shows you are making a transition from the one to the other.

If you are planning to buy a personal computer, you should know some of the basic similarities and differences between PCs and Macs. First of all, both PCs and Macs are composed of the same elements: a CPU, the electronic circuitry to run the computer; memory (hard and/or floppy disk drives) for storing information; 5 input devices such as a keyboard or mouse for putting information into the computer, and output devices such as a monitor, printer, and audio speakers for conveying information. They also have the same uses: PCs are used to communicate on computer networks, to write (with the help of word processing and desktop publishing software), to track finances, and to play games. Macs are likewise used to communicate, write, calculate, and entertain. There are some differences however. Whereas you will find more PCs in business offices, you will find more Macs in classrooms. Although Macs are the computers of choice of people who do a lot of art and graphic design in their work, PCs seem to be the choice of people who do a lot of "number crunching." Finally, there is a difference in the availability of software, vendors, and service for the two computers. In general, there is a lot of PC-compatible 2 software, but relatively little Mac software. Furthermore, for a Mac, you must purchase your machine and get service from a Macintosh-authorized dealer, whereas many different computer stores sell and service PCs.

Analogy.

An analogy is a detailed comparison. This kind of comparison has two uses. First, in reasoning, it may lead to a conclusion that is true of B, the less well known situation, because it is true of A, when B is like A in other important respects. Reasoning by analogy often provides the insights or hunches that result in valuable discoveries. But reasoning by analogy is risky because it assumes that things that resemble each other in some respects do so in all important ones.

City A has parks, attractive residential areas, a university, and good public spirit. City B has parks, attractive residential areas, a university. Therefore, you are asked to believe City B will also have good public spirit. Obviously, such a conclusion does not necessarily follow. City B may have unpleasant town-gown relationships and the people in City B may also be uncooperative in all matters relating to progress. The validity of conclusions based upon this type of analogy must be determined by the facts that exist, not on inferences drawn merely from a set of premises. Such reasoning, however, is outside the purpose of analogy as used in the expository paragraphs which we are considering.

The second use of analogy, which does relate to paragraph writing, is as a way of explaining things. In this kind of analogy, the unfamiliar thing is explained in terms of a familiar one that is similar in certain respects. You use this kind of analogy when you demonstrate the rotation of the earth to a child by means of a ball. This kind of analogy is based upon the resemblance, not the actual likeness, between the things compared.

Such analogies occur most frequently in single sentences. For example:

The mayor governs a city much as a captain rules a ship.

Study the examples of analogy.

The atmosphere of Earth acts like any window in serving two very important functions: to let light in and to permit us to look out and to guard Earth from dangerous or uncomfortable things. A normal glazed window lets us keep our house warm by keeping out cold air. In such a way, the Earth’s atmospheric window helps to keep our planet to a comfortable temperature by holding back radiated heat and protecting us from dangerous levels of ultraviolet light. Just like a window which prevents rain, dirt, and unwelcome insects and animals from coming in, scientists have discovered that space is full of a great many very dangerous things against which our atmosphere guards us.

Light and all other forms of radiation are analogous to water-ripples or waves, in that they distribute energy from a central source. The sun's radiation distributes through space the vast amount of energy which is generated inside the sun. We hardly know whether there is any actual wave-motion in light or not, but we know that both light and all other types of radiation are propagated in such a form that they have some of the properties of a succession of waves.

Paragraph Unity

Unity in the paragraph is essential to good writing. It calls for clear thinking and a definite plan of organization. To make sure your paragraphs are unified, you should begin each one (at least until you develop a good sense of unity) with a topic sentence that states the controlling idea. All your major supporting statements should go directly back to the controlling idea. All minor supports should further explain the major statements and the controlling idea at the same time. Applying the test word because properly and appropriately throughout the paragraph is one sure way of achieving unity. If the topic sentence should have a compound controlling idea, you must develop each part according to the principles of unity.

Study the three paragraphs that follow. All of them discuss the same topic. Which paragraph has unity and which two do not? Which paragraph discusses more than one topic? Which paragraph has irrelevant sentences?

Paragraph 1

The HIV/AIDS epidemic is still growing explosively in most parts of the world. In Central and Eastern Europe, HIV is spreading rapidly in countries that had almost no cases a few years ago. In China, there were an estimated 10,000 HIV-infected persons at the end of 1993, and this total grew ten-fold, to100,000,by the end of 1995. In the countries of sub-Saharan Africa, the HIV/AIDS epidemic rages on. In Kenya, Malawi, Rwanda, Tanzania, Uganda, Zambia, and Zimbabwe, 10 percent of the women visiting postnatal clinics in urban areas are infected with HIV, and in some areas, the rate is 40 percent. Mothers can give the HIV, virus to their children during pregnancy and childbirth or when breast-feeding. The virus is also transmitted through blood and blood products. For example, drug users who share needles may become infected. The main method of transmission is, of course, unprotected sex, which accounts for 75 to 85percent of infections.

Paragraph 2

The HIV/AIDS epidemic is still growing explosively in most parts of the world. In Central and Eastern Europe, HIV is spreading rapidly in countries that had almost no cases a few years ago. In China, there were an estimated 10,000 HIV IV infected persons at the end of 1993, and this total grew ten-fold, to 100,000, by the end of 1995. In the countries of sub-Saharan Africa, the HIV/AIDS epidemic rages on. In Kenya, Malawi, Rwanda, Tanzania, Uganda, Zambia, and Zimbabwe, 10 percent of the women visiting postnatal clinics in urban areas are infected with HIV and in some areas, the rate is 40 percent. Around the world, HIV infection rates are skyrocketing among sex workers.' In Nairobi, Kenya, 80 percent of sex workers are infected, and in Vietnam, the rate of infection climbed from 9 percent to 38 percent between1992 and 1995. These statistics illustrate with frightening clarity that HIV/AIDS is still a major health problem in most areas of the world.

Paragraph 3

The HIV/AIDS epidemic is still growing explosively in most parts of the world. In Central and Eastern Europe, HIV is spreading rapidly in countries that had almost no cases a few years ago. In China, there were an estimated 10,000 HIV infected persons at the end of 1993, and this total grew ten-fold, to100,000, by the end of 1995. There is evidence that in the United States, the United Kingdom, Australia, and New Zealand, HIV infection rates are declining, at least among males. This is a result of a combination of prevention methods. In the countries of sub Saharan Africa, the HIV/AIDS epidemic rages on. In Kenya, Malawi, Rwanda, Tanzania, Uganda, Zambia, and Zimbabwe, 10 percent of the women visiting postnatal clinics in urban areas are infected with HIV, and in some areas, the rate is 40 percent. Although there is no cure for HIV/AIDS, new medicines are available that prolong the lives of people with HIV.