# A Definition is like a Property Line Oros, the Greek word for ‘definition’, means the boundary that demarcates the edge of a man’s field. Such a line shows.

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A Definition is like a Property Line Oros, the Greek word for ‘definition’, means the boundary that demarcates the edge of a man’s field. Such a line shows where the field begins and everything else ends. Like a boundary line, every definition must include something and exclude something.

A Definition is like a Property Line Oros, the Greek word for ‘definition’, means the boundary that demarcates the edge of a man’s field. Such a line shows where the field begins and everything else ends. Like a boundary line, every definition must include something and exclude something.

Precision and Imprecision For a property line to be precise, it must: 1. include what’s supposed to be in 2. exclude what’s supposed to be out. and

Precision and Imprecision Likewise, a precise definition 1. includes everything in the species and 2. excludes everything outside the species.

An imprecise definition is anything that falls short of this. Let’s see how a definition can fall short of this. Precision and Imprecision A precise definition 1. includes everything in the species and 2. excludes everything outside the species.

An imprecise definition 1. excludes something in the species or 2. includes something outside the species. Precision and Imprecision A precise definition 1. includes everything in the species and 2. excludes everything outside the species. How must we conjoin these two requirements? How can it fall short of this requirment?

An imprecise definition 1. excludes something in the species or 2. includes something outside the species. Precision and Imprecision A precise definition 1. includes everything in the species and 2. excludes everything outside the species. A precise definition needs to succeed in both ways… …so it is imprecise if it fails in either way.

An imprecise definition 1. excludes something in the species or 2. includes something outside the species. Precision and Imprecision If a definition fails in one way, it is called “overly broad”, If it fails in another way, it is called “overly narrow”, But if it fails both ways, it is overly broad and overly narrow, and is called “inaccurate”.

Precision and Imprecision Overly narrow Overly broad SPECIES An imprecise definition 1. excludes something in the species or 2. includes something outside the species.

Precision and Imprecision Overly narrow Overly broad An imprecise definition 1. excludes something in the species or 2. includes something outside the species. Inaccurate SPECIES

Quick test for Precision There is a quick test to see whether a definition is precise or not. Ask yourself two questions: Can I think of a counter example, namely: Some __________ that is NOT a __________________. (definiendum) (definiens) OR Some __________ that is NOT a __________________. (definiens) (definiendum)

Quick test for “Too Narrow” There is a quick test to see whether a definition is overly narrow. Some _________is NOT a ____________________. (definiendum) (definiens) Is this statement true? If yes, then the definition is too narrow. If not, the definition is not too narrow. large cat with a maneLion large cat with a maneLion: (such as a lioness!)

Quick test for “Too Broad” flowering plant Tiger Lily: flowering plant There is a quick test to see whether a definition is overly broad. Some ______________is NOT a ____________. (definiens) (definiendum) Is this statement true? If yes, then the definition is too narrow. If not, the definition is not too narrow. Tiger Lily (such as a rose!)

Showing a Definition is Imprecise The definition “ is ” is too narrow/broad (definiendum) (definiens) because the definiens excludes/includes something that is/isn’t in the definiendum; viz. which is/isn’t in the definiendum. (counter example) (definiendum) To formally argue that a definition is imprecise, one uses the following format.

Showing a Definition is Imprecise Man: an animal naturally having exactly two legs. The definition “ is “ is too narrow/broad (definiendum) (definiens) because the definiens excludes/includes something that is/isn’t in the definiendum; viz. which is/isn’t in the definiendum. (counter example) (definiendum) Man an animal w/exactly 2 legs ManBird includesisn’t isn’t broad,

Showing a Definition is Imprecise Biology: the science of animal life. The definition “ is “ is too narrow/broad (definiendum) (definiens) because the definiens excludes/includes something that is/isn’t in the definiendum; viz. which is/isn’t in the definiendum. (counter example) (definiendum) Biology the science of animal life BiologyBotany excludesis is narrow,

Practice circle: a curved shape bird: a feathered flying animal Christian: a follower of Martin Luther pilot: one who flies planes snake: a naturally legless reptile triangle: a polygon w/ 3 equal sides water: a liquid substance fish: a marine animal spray: a jet of finely divided water The definition “A is ” is too narrow/broad (definiendum) (definiens) because the definiens excludes/includes something that is/isn’t in the definiendum; viz. which is/isn’t in the definiendum. (counter example) (definiendum) Use the format below to practice showing the definitions are imprecise.

Homework Print out the Inprecision worksheet from the class website and complete the exercises.

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