Here is the paragraph by which the manufacturer of a time-recording device, writing about the advantages of his system puts in explanation plus argument:
"Every employee keeps his own time and cannot question his own record. All mechanism is hidden and locked. Nothing can be tampered with. The clock cannot be stopped. The record cannot be beaten.
"This device fits into any cost system and gives an accurate record of what time every man puts on every job. It serves the double purpose of furnishing you a correct time-on-job cost and prevents loafing. It stops costly leaks and enables you to figure profit to the last penny."
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Explanation may run in one of many channels. It may point out how the careful selection of raw material makes your product the best, or how the unusual facilities of your factory or the skill of your workmen, or the system of testing the parts assures the greatest value. You might explain why the particular improvements and the patents on your machines make it better or give it greater capacity. The description and the explanation must of necessity depend upon the character of the proposition, but it may be laid down as a general principle that the prospect must be made to understand thoroughly just what the article is for, how it is made, how it looks, how it is used, and what its points of superiority are. Whenever possible, the description and explanation in the letter should be reinforced by samples or illustrations that will give a more graphic idea of the product.
The prospect may be sufficiently familiar with the thing you are selling to relieve you of the necessity of describing and explaining, although usually these supports are necessary for a selling campaign. But it must be remembered that description and explanation alone do not make a strong appeal to the will. They may arouse interest and excite desire but they do not carry conviction as argument does. Some letters are full of explanation and description but lack argument. The repair man from the factory may give a good explanation of how a machine works, but the chances are he would fall down in trying to sell the machine, unless he understood how to reinforce his explanations with a salesman's ability to use argument and persuasion.
And so you must look well to your arguments, and the arguments that actually pull the most orders consist of proofs—cold, hard logic and facts that cannot be questioned. As you hope for the verdict of the jury you must prove your case. It is amazing how many correspondents fail to appreciate the necessity for arguments. Pages will be filled with assertions, superlative adjectives, boastful claims of superiority, but not one sentence that offers proof of any statement, not one logical reason why the reader should be interested.
"We know you will make a mint of money if you put in our goods." "This is the largest and most complete line in the country." "Our factory has doubled its capacity during the last three years." "Our terms are the most liberal that have ever been offered." "You are missing the opportunity of your lifetime if you do not accept this proposition." "We hope to receive your order by return mail, for you will never have such a wonderful opportunity again." Such sentences fill the pages of thousands of letters that are mailed every day.
"Our system of inspection with special micrometer gauges insures all parts being perfect—within one-thousandth of an inch of absolute accuracy. This means, too, any time you want an extra part of your engine for replacement that you can get it and that it will fit. If we charged you twice as much for the White engine, we could not give you better material or workmanship."
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