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since 11.15.04
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Scientific Reasoning
Department of History and Philosophy
Learning Center M33
Lander University
Greenwood, SC 29649
Analogical Arguments
- An analogy is a relationship between two or more entities
which are similar in one or more respects. An analogy is present
whenever the following descriptions are present: resemblance,
similarity, correspondence, likeness, comparison, similitude,
counterpart, image, resemblance of relations and mapping.
- Some of the nonargumentative uses of analogy
include cases in literature and explanation.
- Literary analogies produce a vivid impression
in the reader's mind.
- Metaphor is a figure of speech in
which a word or phrase literally denoting one kind of object
or idea is used in place of another to suggest a likeness
or analogy between them (without the use of "like" or "as").
- E.g., the ship plows the sea.
- E.g., computers have senses and a memory.
- E.g., his fist was a knotty hammer
- Similié is a figure of speech comparing two
unlike things often introduced by the words, "like" or "as."
- E.g., cheeks like roses.
- E.g., "And ice mast high came floating by
As green as emerald."
- "Mary Lou Wingate as slightly made
And as hard to break as a rapier blade."<
- An analogical explanation makes something unfamiliar understandable
by comparing to something more familiar.
- The atom is (like) a miniature solar system.
- A tree is (like) a factory.
- The plum pudding model of the atom is one of electrons surrounded
by a "pudding" of positive charges.
- Scientific reasoning involves the argumentative uses of analogy.
- An analogical inference is drawn from a resemblance of relations.
- J. S. Mill's example of a country which has sent out colonies is
termed "the mother country."
- The colonies stand in the same relation to her as parents do
to their children
- Reasoning by analogy, then, obedience or affection is due by
the colonies to the mother country.
parents → children
mother country → colonies
- An analogical inference proceeds from the similarity of two
or more things in one or more respects to the similarity of those things
in some further respect. (In point of fact, this definition is true of
any inductive argument.)
- The difference between an analogical inference and the case of
a "complete induction" is that there is an invariable connection
between the respects mentioned (c.f., P, Q, R, below).
Thus, in the case of a "complete induction," Mill's Method of
Agreement and Difference cannot be used.
- Even so, these respect must not b known to be unconnected to
each other, for, in this case, the argument would have no
plausibility.
- Hence, no antecedent evidence for a connection in an analogical
inference can be assumed. The analogy is a guidepost for more rigorous
investigation or can be used when subject is out of reach of further
observation and experiment.
- The general form of an analogical argument is as follows,
where a, b, c, d stand for entities, and
P, Q, R stand for respects,
- a, b, c, d all have the attributes P and Q.
- a, b, c all have the further attribute R. [data base]
- _______________________________
- Thus, d probably has the attribute R.
- An analogical inference can be a rigorous induction if the respects
or circumstances of resemblance are the material or fundamental circumstance*
on which all the consequences necessary to be taken into account depend.
(An ultimate property is one that is not a consequence of other properties.
If the resemblance is an ultimate property, there will be resemblance in
the derivative properties.)
- Consequently, analogical arguments can vary in rigor from
accidental to deductive.
One possible extension of the theory of analogy is to extend the kinds of analogies
to other cases. (Note the relevance to classificatory sciences.)
- Analogies of Similarity, as in the general form of an analogical argument.
- Analogies of Diversity, where there is an absence of respects.
- Conflicting Analogies are like Wittgenstein's notion of a family relation. These analogies
are different in some circumstances and similar in others.
- E.g., paintings can be compared to the styles of different masters.
- A vase can have Etruscan, Grecian, and Egyptian respects.
- Consider the following example:
- Smith, Jones, Wilson, and Johnson have whitish lips, pale complexions, and whitish fingernails.
- Smith, Jones, and Wilson have low blood iron levels.
- ________________________________
- Johnson probably has a low blood iron level.
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