Syllogisms And Validity
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Syllogisms And Validity as PDF for free.
More details
- Words: 942
- Pages: 16
Unit 3a SYLLOGISMS AND VALIDITY
19 Arguments Argument- a set of statements on of which appears to be
implied or supported by the others 2 Parts
Premise Conclusion- the statement which appears to be implied by the other statements in the arguments (premises)
An argument can contain more than one premise but
only one conclusion The conlcusion is usually introduced with….thus, therefore, so , or consequently…. A premise is usually introduced with…since, because, for, given that
19 Arguments If a statement is followed by a word that indicates a
premise, the statement will likely be the conclusion. Ex) This statement you are now reading must be the conclusion, because it is followed by the word “because”. Ex) All Mr. S’s Logic students passed the test and Guy is in Mr. S’s Logic class. We must therefore conclude that Guy passed his test. How many premises? What is the conclusion?
19 Arguments Bad argument Ex) All Mr. S’s Logic students passed the test and
Billy is not in Mr. S’s Logic class. We must therefore conclude that Billy did not pass his test. Be careful…true statements can also be bad arguments. Ex) Some musicians are brilliant. Brittney Spears is not a muscian. Therefore Brittney Spears is not brilliant.
20 The Syllogism Categorical syllogism- deductive argument consisting of
three statements in categorical form that together use only three terms called the major, minor and middle. Ex) All red plants are living things All roses are red plants Therefore all roses are living things Or All M are P All S are M T All S are P Note: Three terms
20 The Syllogism All M are P All S are M T All S are P Note: Three terms
S- Minor Term – Subject of the conclusion P- Major Term- Predicate of the conclusion M- Middle term- Term in both premises but not in the conclusion
Ex) All red plants are living things
All roses are red plants Therefore all roses are living things What is minor? Major? Middle?
20 The Syllogism Major Premise – Contains the Major term Traditionally the first premise Minor Premise- Contains the Minor term Traditionally the second premise Ex) All red plants are living things
All roses are red plants Therefore all roses are living things Major premise? Minor Premise? Middle premise? Conclusion? Is the argument true? Are the premises true?
20 The Syllogism All ringed planets are gas giants, so no inner planets
are ringed planets, since no inner planets are gas giants. 1. Find the conclusion (look for key words) 2. Find the major term (P of conclusion) 3. Find the major premise (contains major term) 4. Find the minor premise (contains minor term) 5. Write the syllogism in standard order 1. 2. 3.
All ringed planets are gas giants, No inner planets are gas giants. No inner planets are ringed planets
21 The Mood of Syllogisms Lets use like symbols S is minor P is major M is middle Some black cars are fast cars All Fiat Punto’s are black cars Therefore, som Fiat Punto’s are fast cars Valid or invalid?
Some M are P All S are M T, Some S are P
21 The Mood of Syllogisms Schema- representation of a syllogism having
statments in standard order with standard abbreviations Mood- a three letter description of the types of categorical statements it contains when arranged in standard order
Some M are P (I) All S are M (A) T, Some S are P (I)
Mood is IAI
22 The Figure of Syllogisms Figure- a number form one to 4 identifying the
placement of its middle term Figure 1
Figure 2
Figure 3
Figure 4
Major premise
M is P
P is M
M is P
P is M
Minor premise
S is M
S is M
M is S
M is S
No students are happy students Some boys are students Therfore some boys are not happy students
22 The Figure of Syllogisms
Figure 1
Figure 2
Figure 3
Figure 4
Major premise
M is P
P is M
M is P
P is M
Minor premise
S is M
S is M
M is S
M is S
No students are happy students Some boys are students Therfore some boys are not happy students Schematize:
No M is P Some S is M Some S is not P
Mood- EIO Form- EIO-I
22 The Figure of Syllogisms
Figure 2 EIO- II
Figure 3 EIO- III
Figure 4 EIO- IV
No P is M
No M is P
No P is M
Some S is M
Some M is S
Some M is S
T, Some S is not P
T, Some S is not P
T, Some S is not P
23 Truth and Validity Valid- if and only if the conclusion is necessarily true
given that the premises are true Invalid- if the premises can be true and the conclusion false
All dogs are brown animals All poodles are dogs Therefore, all poodles are brown animals
Is it a valid argument? Is it true?
23 Truth and Validity
All dogs are mammals All dogs are canines Therefore, all canines are mammals.
Is it a valid argument? Is it true? Sound- a syllogism with a valid argument that has
true premises. All dogs are mammals All poodles are dogs Therefore, all poodles are mammals.
23 Truth and Validity
Argument Valid Sound
Invalid Unsound
19 Arguments Argument- a set of statements on of which appears to be
implied or supported by the others 2 Parts
Premise Conclusion- the statement which appears to be implied by the other statements in the arguments (premises)
An argument can contain more than one premise but
only one conclusion The conlcusion is usually introduced with….thus, therefore, so , or consequently…. A premise is usually introduced with…since, because, for, given that
19 Arguments If a statement is followed by a word that indicates a
premise, the statement will likely be the conclusion. Ex) This statement you are now reading must be the conclusion, because it is followed by the word “because”. Ex) All Mr. S’s Logic students passed the test and Guy is in Mr. S’s Logic class. We must therefore conclude that Guy passed his test. How many premises? What is the conclusion?
19 Arguments Bad argument Ex) All Mr. S’s Logic students passed the test and
Billy is not in Mr. S’s Logic class. We must therefore conclude that Billy did not pass his test. Be careful…true statements can also be bad arguments. Ex) Some musicians are brilliant. Brittney Spears is not a muscian. Therefore Brittney Spears is not brilliant.
20 The Syllogism Categorical syllogism- deductive argument consisting of
three statements in categorical form that together use only three terms called the major, minor and middle. Ex) All red plants are living things All roses are red plants Therefore all roses are living things Or All M are P All S are M T All S are P Note: Three terms
20 The Syllogism All M are P All S are M T All S are P Note: Three terms
S- Minor Term – Subject of the conclusion P- Major Term- Predicate of the conclusion M- Middle term- Term in both premises but not in the conclusion
Ex) All red plants are living things
All roses are red plants Therefore all roses are living things What is minor? Major? Middle?
20 The Syllogism Major Premise – Contains the Major term Traditionally the first premise Minor Premise- Contains the Minor term Traditionally the second premise Ex) All red plants are living things
All roses are red plants Therefore all roses are living things Major premise? Minor Premise? Middle premise? Conclusion? Is the argument true? Are the premises true?
20 The Syllogism All ringed planets are gas giants, so no inner planets
are ringed planets, since no inner planets are gas giants. 1. Find the conclusion (look for key words) 2. Find the major term (P of conclusion) 3. Find the major premise (contains major term) 4. Find the minor premise (contains minor term) 5. Write the syllogism in standard order 1. 2. 3.
All ringed planets are gas giants, No inner planets are gas giants. No inner planets are ringed planets
21 The Mood of Syllogisms Lets use like symbols S is minor P is major M is middle Some black cars are fast cars All Fiat Punto’s are black cars Therefore, som Fiat Punto’s are fast cars Valid or invalid?
Some M are P All S are M T, Some S are P
21 The Mood of Syllogisms Schema- representation of a syllogism having
statments in standard order with standard abbreviations Mood- a three letter description of the types of categorical statements it contains when arranged in standard order
Some M are P (I) All S are M (A) T, Some S are P (I)
Mood is IAI
22 The Figure of Syllogisms Figure- a number form one to 4 identifying the
placement of its middle term Figure 1
Figure 2
Figure 3
Figure 4
Major premise
M is P
P is M
M is P
P is M
Minor premise
S is M
S is M
M is S
M is S
No students are happy students Some boys are students Therfore some boys are not happy students
22 The Figure of Syllogisms
Figure 1
Figure 2
Figure 3
Figure 4
Major premise
M is P
P is M
M is P
P is M
Minor premise
S is M
S is M
M is S
M is S
No students are happy students Some boys are students Therfore some boys are not happy students Schematize:
No M is P Some S is M Some S is not P
Mood- EIO Form- EIO-I
22 The Figure of Syllogisms
Figure 2 EIO- II
Figure 3 EIO- III
Figure 4 EIO- IV
No P is M
No M is P
No P is M
Some S is M
Some M is S
Some M is S
T, Some S is not P
T, Some S is not P
T, Some S is not P
23 Truth and Validity Valid- if and only if the conclusion is necessarily true
given that the premises are true Invalid- if the premises can be true and the conclusion false
All dogs are brown animals All poodles are dogs Therefore, all poodles are brown animals
Is it a valid argument? Is it true?
23 Truth and Validity
All dogs are mammals All dogs are canines Therefore, all canines are mammals.
Is it a valid argument? Is it true? Sound- a syllogism with a valid argument that has
true premises. All dogs are mammals All poodles are dogs Therefore, all poodles are mammals.
23 Truth and Validity
Argument Valid Sound
Invalid Unsound
Related Documents
Syllogisms And Validity
June 2020 2
Syllogisms And Validity
June 2020 4
Relilablity And Validity
May 2020 9
Reliability And Validity Examples
May 2020 14
Thursday Validity, Reliability And Generalizability
December 2019 21
Reliability And Validity Hand Outs.docx
November 2019 15More Documents from "Hannah Carmela Sales"
Syllogisms And Validity
June 2020 4
12- Standard Categorical Statements
June 2020 4
6 Statements
June 2020 4
Syllogisms And Validity
June 2020 2