Line Drawing

35 Line Drawing

Alexander E. Hooke

Well, the line has to be drawn somewhere .

Overheard in moral conversations

Many logic or critical thinking textbooks treat the line‐drawing fallacy as a footnote to or subcategory of another fallacy. They view it as a variation of vagueness, false dilemma, slippery slope, or the perfectionist fallacy. A standard definition of this fallacy is “insisting a line must be drawn at some precise point when in fact it is not necessary that such a precise line be drawn” (Moore and Parker 2007 , 221). What determines “not necessary” remains unsettled.

Depending on how one interprets a key premise or central term of the argument, detecting a line‐drawing fallacy can take several forms. Consider a typical exercise in a textbook:

OFFICER:

You are getting a ticket for driving at an unsafe speed.

DRIVER:

Oh, then please tell me what is a safe speed? Is it 50 mph, 45 mph, or should I go so slow that I cause a traffic jam?

The reply illustrates the fallacy if the driver means that safe and unsafe driving cannot be distinguished without a universally exact speed. Asking what made the speed unsafe under the actual conditions would be a legitimate request for an explanation.

This line‐drawing fallacy appears as a form of false dilemma since the driver distorts or limits the either/or options. It can also be a problem of vagueness as the key term “safe driving” is not clarified, to the chagrin of the driver. Line‐drawing concerns also appear in slippery slope, hyperbole, and straw man fallacies. The logical issue is what follows from the absence of a precise boundary, rather than the driver’s tone.

In fact, the driver is implying a challenge to the officer that has perplexed philosophers for centuries. The line‐drawing theme poses inherent intellectual problems. If not carefully addressed, there is always the risk of an absurd or paradoxical conclusion. Unable to answer the driver’s question, we are in danger of saying that there is no difference between safe and unsafe driving. Or, should the officer also suspect the driver of being under the influence, we claim no one can precisely distinguish which drop of alcohol finally constitutes inebriation.

To correct or to prevent such absurd conclusions, logicians try to identify and/or explain the nature of the line‐drawing fallacy. Roy Sorensen, in discussing one of Zeno’s paradoxes, regards the line‐drawing fallacy as a slippery slope. Once you disagree on the preciseness of point A or line B, then all points and lines are disputed. One way to avoid the paradox is to reassess the actual premises. Others view the line‐drawing problem as an extension of the inability to agree on how to measure or evaluate the empirical aspects of an idea or concept. This either/or approach turns the line‐drawing fallacy into a variation of the perfectionist or false dilemma fallacy. Those who emphasize vagueness contend that one or more of the central terms are imprecise and to prevent reaching an absurd conclusion, we need to assess or to agree on these terms.

Such cautions clearly can help the critical thinker to spot overt cases of sloppy thinking. A child told to go to bed at 9 p.m. may ask why 9:01 p.m. is any different. The small difference does not, by itself, show that setting a consistent bedtime is pointless. Becoming a teenager, he or she will learn these arbitrary or imprecise distinctions when considering the proper age to drink or vote, the SAT score a college uses to accept or reject an applicant, when mom or dad are classified as senior citizens, or the official distinction between a freedom fighter and a terrorist. What makes this fallacy so important is that it intertwines with innumerable ordinary and controversial aspects of human life in which people are agreeing on or disputing where to draw the line.

To draw the line is a perennial source of cooperation and conflict. In sporting events, drawing lines demarcates what is in and out of play. In international circles, drawing the line distinguishes respected borders and limits of military aggression. Among social contract theorists, drawing the line might determine where privacy ends and the public begins or when the personal domain becomes part of the communal.

This task is also evident in everyday concerns. Establishing the legal ages for voting or drinking, deciding when use of a stimulant becomes harmful, and distinguishing which student essay is a B+ rather than a B are just a sample of the many instances of when we draw a line, consciously or by habit. The source cites the film Ted 2, which drew rebuke for its humorous take on sickle cell disease. A president of a sickle cell organization called for movie makers and parents “to draw the line” on humor that disparages unfortunate victims of a debilitating disease.

Body-weight categories illustrate why the purpose of a boundary matters. A social description, a clinical assessment and a transport calculation need not use the same criteria. The difficulty of agreeing where to “draw the line” does not make the underlying measurements irrelevant. In its aviation example, the source gives 160 pounds as an earlier assumed average passenger weight. If a planning assumption no longer fits the passengers or their distribution, the calculation needs revision. That is a question about actual mass and balance, not proof that disagreement over labels caused accidents.

A policy debate must distinguish empirical constraints from choices about how to respond. Questions about measurements, seating, costs and fairness require their own evidence and reasons. Neither demanding a cutoff nor proposing one is automatically fallacious.

In light of the above, a simple exercise:

PARENT:

Please stop eating all that junk food. It will make you fat.

CHILD:

What’s wrong with a couple of chips and some ice cream? Do you want me to like those skinny models on TV?

Several line‐drawing‐related fallacies immediately arise, from false dilemma to straw man (distorting the parent’s point). Yet this exercise is too obvious to help a student discern the underlying difficulty in recognizing the line‐drawing fallacy or avoiding the paradox it raises. As a potential critical thinker, the student or child might acknowledge his or her youthful moment of illogic, but then offer this more earnest rejoinder to the parent: “OK, but where do I draw the line? Exactly how do I decide when an occasional treat becomes too much snacking, or at which pound am I no longer normal but overweight?” While we don’t expect youthful respondents to have Aristotle’s “means between the extremes” in the back of their minds, their questions seek some counsel about when or where to draw the line.

Margaret Cuonzo, in a lucid and scholarly discussion of paradoxes, devotes considerable attention to the sorites problem (the more formal category of line drawing) and possible solutions. One she proposes involves the notion of “folk concepts.” These are ordinary-language terms whose imprecision can complicate communication and deliberation. Folk concepts such as baldness, space, pollution, fear, time, forgiveness, or beauty are important in everyday deliberations even though users of these concepts are unable to pin down their exact definitions, for example, the precise moment when dirty air becomes smog and when smog becomes pollution.

A shortcoming to the folk concepts approach is that folk concepts themselves are hardly univocal in their meanings or standards. To assert that someone is skinny, normal, or fat is often based on tacit or subjective standards. They might rely on different criteria to make sensible judgments about beauty, health and longevity, functionality, liability for insurance companies, even the risk factor for flying in a small plane.

While the line‐drawing fallacy can be subsumed under more standard fallacies, it warrants distinct attention insofar as it raises a perennial problem in everyday thinking and important disputes. Textbook exercises tend to present obvious cases of the fallacy. This has the inadvertent effect of students accepting the charge and moving on.

Before labeling an argument fallacious, ask why a boundary is needed, how precise it must be and what reasons support the proposed cutoff. That separates a useful request for guidance from the claim that no distinction is possible.