Out of the blue
What do words like “tall” or “old” or even “green” and “blue” have in common? They all fall into a category of vague words that cause much debate among philosophers, linguists and other interested parties, according to Professor Diana Raffman from U of T Mississauga’s Department of Philosophy.
“We all have an intuitive sense of what vagueness is – it refers to any unclarity in our speech,” said Raffman in the lecture held on January 27, recognizing her exceptional scholarly achievements as a recipient of the 2015 Research Excellence Award, which is given annually at UTM.
"But I think the best definition of linguistic vagueness is that it’s the property of possessing blurred or fuzzy boundaries of application.” Prime examples of vague words are ‘old,’ ‘adult,’ ‘juvenile,’ and colour words like ‘blue’ and ‘green:’ there is no clear boundary between people who are old and people who are middle-aged, or between adults and juveniles, or between blue and green.
Raffman went on to outline her approach for tackling the vagueness of language in her research, the inherent problems that arise as a result of this lack of clarity, and why we should care about vagueness.
She explained that one of the most notorious problems caused by linguistic vagueness is the sorites paradox, an unsolved Ancient Greek puzzle from 200 B.C. The puzzle is generated by “slippery slope reasoning” whereby one step down the slope forces you to make all subsequent steps, leading to an absurd conclusion.
For example, consider a series of people progressing from an adult aged 35 to a juvenile aged 14, where each person’s age is one day younger than the last. Since an interval of one day can never change an adult into a juvenile, or more generally change an adult into a non-adult, it looks as if we are forced to say that all of these people are adults; if two people differ in age by a single day, then if one of them is an adult, so is the other. (What causes this strange result is the so-called tolerance of the vague word ‘adult;’ it tolerates small differences in age.) However, we know that not all of these people are adults; in particular, a 14-year-old is not an adult, said Raffman.
But the paradox can be solved by understanding certain features of our use of vague words, she said, pointing to the results of an experiment she ran with two psychologist collaborators from Ohio State University. Subjects were shown a series of coloured patches progressing from a clear blue to a clear green. They had to classify each patch either as blue, or as green, or as a borderline case. In these classifications, Raffman and her colleagues found a pattern called hysteresis, where a system tends to remain in a certain state once it’s gone into that state. When subjects were shown the coloured patches one at a time, immediately after they shifted from saying ‘blue’ to saying ‘green,’ they were shown the preceding patch they had just classified as blue. Now, they classified that preceding patch also as green, even though they had classified it as blue just a few seconds before. This pattern is hysteretic.
According to Raffman, hysteresis makes it possible for us to stop saying ‘blue’ (or 'adult') and start saying ‘green’ (or 'juvenile') without imposing an unjustified boundary between the two categories; hysteresis blurs the shift from blue to green (or from adult to juvenile). This feature of vague words “allows us to talk about the world around us, which changes continuously,” said Raffman. And in other words, she explains, the hysteresis enables us to stop sliding down the slippery slope.
The most significant instance where vagueness becomes problematic, and where we should care about it, she said, is in the law. She cited numerous examples where the vagueness of words has fueled debate, such as in the abortion controversy (when personhood begins), or regarding the question of when a person’s IQ is high enough to make him eligible for execution (this question arose recently in a U.S. Supreme Court case), or in cases where the vague boundary between being an adult and being a juvenile makes the appropriate sentence for a crime unclear.
The host for the Research Excellence Lecture, Professor Bryan Stewart, was thrilled with the turnout, the outstanding calibre of the lecture and the engaged audience, consisting of staff, faculty and students from a diverse mix of departments. “This captures exactly what I envisioned for this event, and is a prime example of what the annual Research Excellence Lecture should be,” said Stewart.