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Shades of Gray
| Article
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19721 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
9 / 1991 |
2,147 Words |
| Author
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Hank Hogan
Hank Hogan is a science writer in Austin, Texas. |
Is it raining or isn't it? A look out the window usually gives us the answer. But suppose it's one of those gray days, when clouds are hugging the ground and suspended water droplets adhere to anything that moves. Is it raining? A budding young scientist recording rain days with a one and nonrain days with a zero would have to make a choice--either it is raining or it isn't. This apparently simple example illustrates a fundamental point about science.
A surprising amount of Western science is based on a logic system that defines either-or categories. Either a thing is A or it is not A. Either it is raining or it isn't. Shades of gray are lost in the rounding process.
Since the time of Aristotle, for nearly 2,400 years, Western thought has been dominated by the idea that for any category there are only two possibilities--an object either is in that category or it isn't. An animal either is a dog or it isn't. It can't partly be a dog. If part-dogs exist then we need to define a different category.
As scientists have developed computers and the programs that direct them, the two-valued Aristotelian logic has naturally been incorporated into both the heart of the computer and the computer's programs. For many computer applications, such as spread sheets and word processing, the two-valued, black-and-white approach works very well. For other subtle, yet relatively simple, operations like focusing a camera or accelerating a train, the two-valued approach is cumbersome and slow. An apparently simple task is rendered complex because the real world situation doesn't conform to the computer's black-and white view of the world.
The difference between the way two-valued computer programs are able to view the world and the way the world actually is has so far kept computers from doing a very good job controlling tasks that lack sharp edges and precise definitions. A new approach called fuzzy logic is showing promise as a way for computers to successfully deal with the world's ambiguities. Results so far have been very encouraging and fuzzy logic is already being used in a host of commercial products.
Modes of reasoning
The name "fuzzy" originated with Lotfi A. Zadeh, a professor of electrical engineering and computer science at Berkeley. In 1965 he published a paper entitled "Fuzzy Sets" in which he developed the concepts behind fuzzy logic and
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