Logical Gal and featherless bipeds

28 May

Apparently Plato defined man as a ‘featherless biped’. 

Featherless biped

And ever since, philosophers have used his wording as an example of a poor definition.  The photo proves the point!

But there is another consideration. Is the phrase ‘featherless biped’ a description or a definition?  And what is the difference?

A definition is actually the technical evaluation of a term  (called the definiendum) that includes the definiens or the cluster of words used to set out clearly what the speaker or writer means.  An adequate definition :

  • will refrain from using the term being defined  – as in  ‘a human is an animal which has a human parents’
  • will employ a genus and a differentia  – a fork is an eating utensil (genus) that has prongs to spear food (differentia)  Think of genus as the family of items and the differentia as the distinguishing characteristics of each member.  So a spoon would belong to the genus of  eating utensil, and its differentia could be this- bowl-shaped on one side to scoop up liquids or soft food.
  • will be mutually exclusive and jointly exhaustive – both considerations work to PIN DOWN PRECISELY what is meant, thereby avoiding both a situation where ‘family members’ could be assigned to more than one group (NOT mutually exclusive) OR a situation where a ‘family member’ has been left out (in this case the definition would NOT meet the requirement of being jointly exhaustive)

 

  • Precision
  • will avoid negative language,  metaphors and  vague or cumbersome language meant to obfuscate the meaning
  • will focus on what is essential to the concept

So a human being as defined by one on-line dictionary offers this:

Thinking and Talking Humans

“A man, woman or child of the species Homo Sapiens distinguished from other animals by superior mental development, power of articulate speech, and upright stance.”

In assessing what makes for a good definition, the attribute that comes to mind is ‘functional’, as in What’s THAT for? 

So how do descriptions differ from definitions?

A simple way to look at a description is to see it as merely one aspect or representation of a concept.  Attention is NOT given to meeting all the above requirements of a ‘good’ definition:   Think SINGLE-orbed v. FULLY-orbed.

For example, one might ‘DESCRIBE’  a musician as someone who enjoys performing  vocal or instrumental sounds.  That is just one venue for musicians.

musicians

 

So why are definitions and descriptions important? Because they can either further, facilitate or hinder understanding.  I witnessed this Saturday during a debate between an atheist and a Christian.  They were at odds with each other over the definition or description of the term FAITH!

  • The atheist, Peter Boghossian, advanced a definition of faith as believing something for which you have no evidence.
  • The Christian, Tim McGrew, pushed back and said that the Oxford English Dictionary describes/defines faith as trust warranted by a certain degree of evidence.

Evidence

I want all you Logical Joes and Janes to know that these 2 men spent about 20 minutes going round and round arguing over which definition the majority of people subscribe to.  Definition of terms IS the beginning of all debate and discussion.  And if no agreement is reached, the discussion that might ensue will be very frustrating!

Question:  Where have you encountered such confusion or disagreement over terms?

 

 

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