Archive for the ‘Complex sentences’ Category

How to phrase a complex sentence in a clear, unambiguous fashion

January 6, 2008

Complex sentences oftentimes contain and, or, and not. There are various ways to express anded sentences, ored sentences, and noted sentences. Depending on which way you use, a sentence can be easily understood or ambiguous.

Suppose we denote the sentence “I will go shopping today” by the letter A, i.e.

Let A = I will go shopping today.

And likewise for these sentences:

Let B = I will do cleaning today.

Let C = I will call my Mother today.

We can translate the negation of A in any of these ways:

  • It is not the case that I will go shopping today.
  • It isn’t true that I will go shopping today.
  • I will not go shopping today.
  • I won’t go shopping today.

We can translate A and B in any of these ways:

  • I will go shopping today and I will do cleaning today.
  • I will both go shopping today and do cleaning today.

We can translate A or B in any of these ways:

  • I will go shopping today or I will do cleaning today.
  • I will either go shopping today or do cleaning today.

Now suppose that we need to combine the sentences in more complex ways.  For example:

(not(A) and B) or (not(C))

For not(A) there are four ways to translate it.  Which way should we use?  Our choice can have a big impact on the understandability of the final sentence.  Likewise for anding and oring.  Here’s one way to express it:

I will not go shopping today and I will do cleaning today or I will not call my Mother today.

Although the sentence is technically correct, it’s somewhat confusing because the parentheses are gone and everything runs together.  A good way to clean it up is to express it as:

Either I will not go shopping today and I will do cleaning today or I will not call my Mother today.

The word either clarifies just how much the word or is meant to encompass.   Thus the words either and or act in combination like parentheses.

– Extracted from Logic for Dummies by Mark Zegarelli


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