Reasoning by analogy is using a comparison as part of an argument. One side of the comparison is the conclusion and the "other side should conclude the same." However, not every comparison is an argument.
Epstein uses the example, “My love is like a red, red rose.” This is a comparison only because no conclusion is drawn. This would normally be called an analogy. However, analogies are “often only suggestions for arguments,” that must be taken “seriously” because they are used in “science, law, and ethics.”
To tell if an analogy is good we must pick out important similarities that can be used as premises. We need to ask the question “So?” so we can decide whether or not an analogy is good. Some similarities do not apply or matter, while others are vague and therefore, we cannot use them. We need to come up with some principle that applies to both sides. We need to ask questions like, “Are all premises true?” “Is the argument good?” Next, we have to look for the differences to see if there is any reason the "general principle" may not apply to one of the sides.
Saturday, July 24, 2010
Friday, July 23, 2010
REASONING BY ANALOGY
Reasoning by analogy is using a comparison as part of an argument. One side of the comparison is the conclusion and the "other side should conclude the same." However, not every comparison is an argument.
Epstein uses the example, “My love is like a red, red rose.” This is a comparison only because no conclusion is drawn. This would normally be called an analogy. However, analogies are “often only suggestions for arguments,” that must be taken “seriously” because they are used in “science, law, and ethics.”
To tell if an analogy is good we must pick out important similarities that can be used as premises. We need to ask the question “So?” so we can decide whether or not an analogy is good. Some similarities do not apply or matter, while others are vague and therefore, we cannot use them. We need to come up with some principle that applies to both sides. We need to ask questions like, “Are all premises true?” “Is the argument good?” Next, we have to look for the differences to see if there is any reason the "general principle" may not apply to one of the sides.
Epstein uses the example, “My love is like a red, red rose.” This is a comparison only because no conclusion is drawn. This would normally be called an analogy. However, analogies are “often only suggestions for arguments,” that must be taken “seriously” because they are used in “science, law, and ethics.”
To tell if an analogy is good we must pick out important similarities that can be used as premises. We need to ask the question “So?” so we can decide whether or not an analogy is good. Some similarities do not apply or matter, while others are vague and therefore, we cannot use them. We need to come up with some principle that applies to both sides. We need to ask questions like, “Are all premises true?” “Is the argument good?” Next, we have to look for the differences to see if there is any reason the "general principle" may not apply to one of the sides.
What do you practice? Forgiveness or revenge?
An “appeal to spite” is another appeal to emotion when communicating and/or persuading others. Basically, it is getting revenge, getting even, or getting back at someone for doing you wrong. In Epstein, p. 193, it states that this is usually rejected “as bad by some people on moral grounds.” However, “In some cultures…it’s not only acceptable, but a moral imperative…to preserve one’s ‘honor.’” So some people find it bad and others find it a necessary defense reaction.
Also, an “appeal to spite” often invokes the "two wrongs MAKE a right" principle.
When I was growing up, I was taught the total opposite, that two wrongs DON’T make a right! And I try to live by that rule. However, as the book states, an “appeal to spite” is when a person does something bad or mean to you and you respond with doing something bad or mean to them. This is another emotion people use in the art of communication. In other words, it is used to persuade someone to do something based on revenge.
It’s not good in my book! But, you can make your choice and suffer the consequences. Hmmm…..was that just an appeal to fear statement I just made? We’ll leave that for another post! :o)
Also, an “appeal to spite” often invokes the "two wrongs MAKE a right" principle.
When I was growing up, I was taught the total opposite, that two wrongs DON’T make a right! And I try to live by that rule. However, as the book states, an “appeal to spite” is when a person does something bad or mean to you and you respond with doing something bad or mean to them. This is another emotion people use in the art of communication. In other words, it is used to persuade someone to do something based on revenge.
It’s not good in my book! But, you can make your choice and suffer the consequences. Hmmm…..was that just an appeal to fear statement I just made? We’ll leave that for another post! :o)
Sunday, July 18, 2010
What is a Categorical Syllogism?
ARISTOTELIAN LOGIC: WHAT THE HECK IS A CATEGORICAL SYLLOGISM? 7/17/10
What in the world is a categorical syllogism? It is “an argument composed of three categorical claims, two premises and a conclusion. The three claims use three terms as subject or predicate, each of which appears in exactly two of the claims.” Got that?? ;o)
The book offers up the following:
No police officers are thieves.
Some thieves are sent to prison.
So no police officers are sent to prison.
The terms “police officers,” “thieves,” “people sent to prison,” appear in two of the claims. Aristotelian logic “identifies the predicates and subjects in syllogisms by the roles they play in determining whether the argument is valid.” For example, major, minor, and middle terms, and major and minor premises. Aristotelians “identify the predicates and subjects in syllogisms by the roles they play in determining whether the argument is valid.” Epstein p. 381.
Epstein states that the major term is: people sent to prison. The minor term is: police officers. The middle term is: thieves. And the major PREMISE is: “Some thieves are sent to prison.” Therefore the minor PREMISE is “No police officers are thieves.”
Aristotelian logic focuses on showing that we can “mechanically determine any given categorical syllogism whether it is valid or invalid. One way to do that is by inspecting its form.” AL lists all forms of syllogisms into STANDARD FORM. The claims are in standard, major premises is first, minor is next, and the conclusion follows. Then you go down each line and determine whether it is valid or invalid.
What in the world is a categorical syllogism? It is “an argument composed of three categorical claims, two premises and a conclusion. The three claims use three terms as subject or predicate, each of which appears in exactly two of the claims.” Got that?? ;o)
The book offers up the following:
No police officers are thieves.
Some thieves are sent to prison.
So no police officers are sent to prison.
The terms “police officers,” “thieves,” “people sent to prison,” appear in two of the claims. Aristotelian logic “identifies the predicates and subjects in syllogisms by the roles they play in determining whether the argument is valid.” For example, major, minor, and middle terms, and major and minor premises. Aristotelians “identify the predicates and subjects in syllogisms by the roles they play in determining whether the argument is valid.” Epstein p. 381.
Epstein states that the major term is: people sent to prison. The minor term is: police officers. The middle term is: thieves. And the major PREMISE is: “Some thieves are sent to prison.” Therefore the minor PREMISE is “No police officers are thieves.”
Aristotelian logic focuses on showing that we can “mechanically determine any given categorical syllogism whether it is valid or invalid. One way to do that is by inspecting its form.” AL lists all forms of syllogisms into STANDARD FORM. The claims are in standard, major premises is first, minor is next, and the conclusion follows. Then you go down each line and determine whether it is valid or invalid.
Saturday, July 17, 2010
REVISED - SAY WHAT??
Why is it so much trouble to communicate well? I mean will we have to "diagram" every time we speak?? I don't think so!! As we practice these formulas, over time we will get better and faster at them. We will be able to spot whether a claim is true or false and "how it is compounded from other claims." How compound claims use the words (and, or not if...then...) "depends on the truth or falsity (truth-value) of the claims from which they are built." We are not to rely on anything else except "whether the claim is true or false and how it is compounded from other claims." (Epstein, p. 359)
The symbols used for these words are ˄ for and, ˅ for or, ┐for not, and → for if…then…
Example, Jill is a girl and John is a boy. When is this true? When both are true. According to Epstein, this is the only way it can be true. Epstein p.360.
A personal example is Mary is a classical pianist and Johnny is a tenor. Based on my personal experience, I know both of these statements to be true. The only way this can be true is when both statements are true and in this case they are.
The symbols used for these words are ˄ for and, ˅ for or, ┐for not, and → for if…then…
Example, Jill is a girl and John is a boy. When is this true? When both are true. According to Epstein, this is the only way it can be true. Epstein p.360.
A personal example is Mary is a classical pianist and Johnny is a tenor. Based on my personal experience, I know both of these statements to be true. The only way this can be true is when both statements are true and in this case they are.
SAY WHAT?? THE TRUTH?? WHAT'S THAT?
Why is it so much trouble to communicate well? I mean will we have to "diagram" every time we speak?? I don't think so!! As we practice these formulas, over time we will get better and faster at them. We will be able to spot whether a claim is true or false and "how it is compounded from other claims."
How compound claims use the words (and, or not if...then...) "depends on the truth or falsity (truth-value) of the claims from which they are built." We are not to rely on anything else except "whether the claim is true or false and how it is compounded from other claims." (Epstein, p. 359)
The symbols used for these words are ˄ for and, ˅ for or, ┐for not, and → for if…then… These symbols help us be precise about "how we will understand these words in arguments, relative to the classical abstraction.
CLASSICAL ABSTRACTION:
The only aspects of a claim we'll pay attention to are whether the claim is true or false, and how it is compounded from other claims.
For example, Jill is a girl and John is a boy. When is this true? When both are true. According to Epstein, this is the only way it can be true. Epstein p.360.
Friday, July 16, 2010
GENERAL CLAIMS ARE SO GENERAL! :O)
General claims, as described in Chapter 8 of Richard L. Epstein's book Critical Thinking, that "assert something in a general way about all or a part of a collection," can seem valid, but can also be bad arguments even if they sound right. We need to look more closely at them and avoid "getting lured into belief" of those claims by clarifying words such as "all, some, no," and "only."
Epstein further defines that:
There is another way to check the validity of these claims by using diagrams such as the "direct way of reasoning" and "arguing backwards" with "all" and "no" and "reasoning in a chain" with "all" and "some."
Remember that the contradictory of a general claim is "one that always has the opposite truth-value." For example, the contradictory of "All dogs bark." is "Some dogs don't bark."
Using the ALL word, my personal example is when I was on Facebook I noticed that a friend wrote a statement that said, "Higher learning is the absurd, perpetuation of lies and unfounded fantasies." For privacy reasons, I won't give my friend's name. But I thought that was a very stupid comment. In this case, the ALL definition used here is "Every single one, no exceptions." My friend is basically saying that ALL higher learning is this way. Any reasonable critical thinker would see that this is an invalid statement that falls on its face because it has nothing to support it. No legs, man, no legs!!
Epstein further defines that:
All means "Every single one, no exceptions." Sometimes all is meant as "Every single one, and there is at least one." Which reading is best may depend on the argument.
Some means "At least one." Sometimes some is meant as "At least one, but not all." Which reading is best may depend on the argument.
No means "not even one," "every single one is not."
Only "Only S are P" means "All P are S."
There is another way to check the validity of these claims by using diagrams such as the "direct way of reasoning" and "arguing backwards" with "all" and "no" and "reasoning in a chain" with "all" and "some."
Remember that the contradictory of a general claim is "one that always has the opposite truth-value." For example, the contradictory of "All dogs bark." is "Some dogs don't bark."
Using the ALL word, my personal example is when I was on Facebook I noticed that a friend wrote a statement that said, "Higher learning is the absurd, perpetuation of lies and unfounded fantasies." For privacy reasons, I won't give my friend's name. But I thought that was a very stupid comment. In this case, the ALL definition used here is "Every single one, no exceptions." My friend is basically saying that ALL higher learning is this way. Any reasonable critical thinker would see that this is an invalid statement that falls on its face because it has nothing to support it. No legs, man, no legs!!
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