Last week we tripped into the tangled definition of what life is. An apparently simple question hides a messy answer.
When you think about it, it's not just "life" that gives us trouble (a metaphor if ever there was one). It's extremely hard to find any definition that fits perfectly into a box.
If you're reading this while sitting on a chair, grab a saw and cut the backrest down to 15cm. Still a chair? Now cut again to make it 5cm. At what point would you call it a stool instead of a chair?
You can try this with any object around the home (at your own expense). When does a knife become a spoon, or spoon become a fork?
This is no trivial thought exercise because it has serious ramifications. The boundary between "alive" and "dead" makes a huge difference to life insurance or even criminal matters. Is "dead" when there is no heartbeat, or is it the lack of a brain signal?
An example of the considerable amount of work and expertise that goes into this is the US Diagnostic and Statistical Manual of Mental Disorders (DSM). The blurb explains that it is the "product of more than 10 years of effort by hundreds of international experts in all aspects of mental health".
The DSM is used by the health system to classify mental disorders for diagnoses, treatment and research.
A diagnosis of schizophrenia requires (in part) a significant impact on social or occupational functioning for at least six months. That means a person with those symptoms for five months does not qualify and the meaning "significant" is open to interpretation.
If you were affected by a condition such as one in the DSM, it could change whether you're entitled to health benefits.
No matter how hard we try, definitions become rubbery, but they have real-life consequences.
Imagine then, the hellish world of a bureaucrat who must decide whether or not a chicken drumstick attracts GST.
The Tax Office lists sporting venues where the product is sold, including swimming pools and tennis centres. It doesn't mention ping pong halls, so that requires an opinion. And is it a social club or a business? Is a semi-raw drumstick ''cooked''?
Computers are generally very bad at handling vague definitions. It's not that long ago that gender was deemed a binary category - you're either male or female and nothing in between.
A method to address the vagaries of definitions was invented decades ago, but is rarely used in government systems.
Fuzzy Logic admits degrees of classification so that maybe a person might be, say, 70 per cent man, making them man-ish.
Fuzzy Logic is also a science program on radio 2XX and a column in ACM newspapers.
Listen to the Fuzzy Logic Science Show at 11am Sundays on 2XX 98.3FM.
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