'''Well done!''' 
Your answer is correct!

[http://www.lexical-resource-semantics.de/wiki/index.php/Syllogism#Exercise_4 '''Back to Exercise 4''']

Syllogism4a

2013-03-22T12:18:51Z

'''Well done!''' 
Your answer is correct!

[http://www.lexical-resource-semantics.de/wiki/index.php/Syllogism#Exercise_4 '''Back to Exercise 4''']

Syllogism3c

2013-03-22T12:18:33Z

'''Well done!''' 
Your answer is correct!

[http://www.lexical-resource-semantics.de/wiki/index.php/Syllogism#Exercise_4 '''Back to Exercise 4''']

Syllogism1c

2013-03-22T12:18:16Z

Anna:

'''Well done!''' 
Your answer is correct!

[http://www.lexical-resource-semantics.de/wiki/index.php/Syllogism#Exercise_4 '''Back to Exercise 4''']

Syllogism5c

2013-03-22T12:17:25Z

Anna: Created page with "'''Sorry!''' Unfortunately, your answer is incorrect. [http://www.lexical-resource-semantics.de/wiki/index.php/Syllogism#Exercise_4 '''..."

'''Sorry!''' 
Unfortunately, your answer is incorrect.

[http://www.lexical-resource-semantics.de/wiki/index.php/Syllogism#Exercise_4 '''Back to Exercise 4''']

Syllogism5a

2013-03-22T12:17:04Z

Syllogism4c

2013-03-22T12:16:49Z

Syllogism4b

2013-03-22T12:16:31Z

Syllogism3b

2013-03-22T12:16:12Z

Syllogism3a

2013-03-22T11:42:25Z

Anna:

This answer is wrong, Try again!

[http://www.lexical-resource-semantics.de/wiki/index.php/Syllogism#Exercise_4 '''Back to Exercise 4''']

Syllogism1a

2013-03-22T11:41:59Z

Anna:

This answer is wrong, Try again!

[http://www.lexical-resource-semantics.de/wiki/index.php/Syllogism#Exercise_4 '''Back to Part 1''']

Syllogism1a

2013-03-22T11:40:40Z

Anna:

This answer is wrong, Try again!

[http://www.lexical-resource-semantics.de/wiki/index.php/NMTS-Group2#Exercise_4 '''Back to Part 1''']

Syllogism1a

2013-03-22T11:39:14Z

Anna: Created page with "This answer is wrong, Try again!"

This answer is wrong, Try again!

Syllogism

2013-03-22T11:38:41Z

Anna: /* Exercise 4 */

{{MaterialUnderConstruction}}

=Syllogism=

/ˈsɪləˌdʒɪzəm/

==Definition==

A [[wikipedia:Syllogism|syllogism]] is a logical argument composed of three parts: the major premise, the minor premise, and the conclusion inferred from the premises. 

According to Patrick Hurley a standard-form categorical syllogism is one which meets ''the four conditions''. First of all, the three statements must be standard-form categorical propositions. Second of all, the two occurrences of each term should be the same. What is more, each term must be use in the same sense throughout the argument. And finally the major premise occurs first and it is followed by minor premise and the conclusion is the last one. 
The first condition means that each statement needs a proper quantifier, subject term, copula and predicate term. The second statement is very clear and the third one excludes the possibility of equivocation. It means for instance that if there is a syllogism that contain a word men and it is used in two different senses for example in one term in the sense of human beings in one statement and in the sense of male human beings in another statement, The syllogism would contain then more than three terms and that is why it would be not in standard form. The last condition says that these three statements must be listed in the right order. 

I will help you to understand the syllogism you just need to follow this article step by step.

== Steps==

=== First Step===

First thing that you have to know is the basic structure of syllogism. As you already know the syllogism consists of three propositions : 
#major premise 
#minor premise and 
#conclusion 

in which there appear a total of exactly three categorical terms, each of which is used exactly twice. Each of the premises has one term in common with the conclusion: the major term in the major premise, which forms the predicate of the conclusion, and the minor term in the minor premise, which forms the subject of the conclusion. The categorical term in common in the premises is called the "middle term". For instance:

'''Major premise:''' ''No geese are felines. ''
'''Minor premise:''' ''Some birds are geese. ''
'''Conclusion:''' ''Therefore, Some birds are not felines. ''

In this example you can see that "felines" is the ''major term'' and ''predicate of the conclusion'', "bird" is the ''minor term'' and ''subject of the conclusion'', and "geese" is the ''middle term''.

===Second Step===

It is easier when you try to think of each term as representing a category. For instance "plant" is a category composed of everything that can be described as a plant.

===Third Step===

You can notice that each part is expressed as "Some/all/no S is/are [not] P," and have four possible variation. The universal affirmative (symbolized as A) is expressed as "all S is/are P,". The universal negative (symbolized as E) is expressed as "no S is/are P,". The particular affirmative (symbolized as I) is expressed as "some S is/are P,". The particular negative (symbolized as O) is expressed as "some S is/are not P,". This you can see in the table below: 

'''A''' |All |''S'' |are |''P'' |'''universal affirmatives''' |''All humans are mortal''. 
'''E''' |No |''S'' |are |''P'' |'''universal negatives''' |''No humans are perfect''. 
'''I''' |Some |''S'' |are |''P'' |'''particular affirmatives''' |''Some humans are healthy''. 
'''O''' |Some|''S'' |are not |''P'' |'''particular negatives''' |''Some humans are not clever''. 

('''S''' is a Subject, '''P''' is a Predicate)

The mood classification derives from medieval logicians. The mood of categorical syllogism is a statement of which categorical propositions such as A, E, I or O consist of, placed in the same order in which they occur in the standard form. For instance, if the major premise is an A proposition, the minor premise an O proposition, and conclusion an E proposition, the mood is AOE. Another example: a syllogism with the mood of OAO has an O proposition as its major premise, an A proposition as its minor premise and an O proposition as its conclusion and the like. In order to determine the mood of a categorical syllogism we are first supposed to put the syllogism in the standard form and note the letter name of the statements to the side of each. This is how we create the mood of syllogism, reading the letter for the major premise first, then the letter for the minor premise and finally the letter for the conclusion.

===Fourth Step===

The fourth step is to determine the figure of the syllogism. Depending on whether the middle term serves as subject or predicate in the premises, a syllogism may be classified as one of four possible figures.

There are four different arrangements possible. In the first figure syllogism the middle term is the subject term of the major premise and the predicate term of the major premise. In the second figure, the middle term is the predicate term of both premises. In the third figure, the subject term of both premises and in the last fourth figure, the middle term occurs as the predicate term of the major premise and the subject term of the minor premise. The letter S represents the subject of the conclusion, minor term; P represents the predicate of the conclusion, major term, and M stands for the middle term, and leave out the quantifiers and copulas.

You can click on this link to see the table which illustrate it:

[[File:Figure.pdf|500px]]

===Fifth Step===

For the next step you have to decide if the syllogism is valid. A valid Argument is an argument whose premises are true and then the conclusion has to be true. If a syllogism is valid it is not possible for its premises to be true while its conclusion is false. An example of valid argument can be: There are over seventy students in this classroom; therefore, there are over ten students in this classroom.

==Attention==

You have to be aware that the fallacy of illicit minor and illicit major can occur. A formal fallacy committed in a categorical syllogism that is invalid because its major term is undistributed in the major premise but distributed in the conclusion is called ''illicit major''. The example of this fallacy is in the form All A are B; no C are A. Therefore, no C are B. For instance, "All cats are animals"; "no dogs are cats"; therefore, "no dogs are animals": this syllogism is invalid because the major term "animals" is undistributed in the major premise, but distributed in the conclusion.

Categorical syllogism that is invalid because its minor term is undistributed in the minor premise but distributed in the conclusion committed the fallacy of the ''illicit minor''. An example of this is in the form All A are B; all A are C. Therefore, all C are B. For instance, "All cats are mammals"; "all cats are animals"; therefore, "all animals are mammals": this syllogism is invalid because the minor term "animals" is undistributed in the minor premise (because not all animals are cats), but distributed in the conclusion.

==Tip==

If I awake your interest about the syllogism, and you want to know more details, you can click on this link: [[wikipedia:Syllogism|syllogism]] or read ''A concise introduction to logic'' by Patrick Hurley or ''Aristotelian Logic'' by W. Parry.

==Exercises==

Hier you can check your knowledge about the syllogism. There are different types of exercises. Have fun while doing them.

===Exercise 1===

'''Indicate whether the following arguments are ''valid'' or ''invalid''. If the syllogism is ''invalid'' indicate which rule of logic was violated. For the solutions, mark the following paragraph (which is seemingly empty) with your mouse. '''

'''Hint:''' you can ''first'' think about: what is the middle term of the syllogism. Then what kind of statment is the first permise is that: A, I, E or O, and what kind of statment is the conclusion. 
''Second'' you can check if the middle term is distributed at least once. If it is not, you do not need to proceed further, the syllogism is invalid. 
''Third'', if there are any distributed terms in the conclusion, check to see if those very terms are distributed in the premises. 
''Finally'' check the rest of the rules. If no rules are violated, the syllogism is valid.

1. Nothing easy is worthwhile. 
Nothing good is easy. 
Therefore, nothing good is worthwhile. 

 '''''Perfect!!''''' 
This syllogism is '''invalid'''. No conclusion can be drawn from two negative premises. 

2. All married people know about marriage problems. 
No priests are married people. 
Therefore, no priests know about marriage problems. 

 '''''Correct!!''''' 
This syllogism is '''invalid''' because “Know about marriage problems” is distributed in the conclusion, but is undistributed in the first premise. 

3. Mathematicians know what mathematics is. 
No philosopher is a mathematician. 
Therefore, no philosopher knows what mathematics is. 

 ''Invalid'', '''''Easy one, right??''''' 
“Knows what mathematics is” is distributed in the conclusion, but is undistributed in the first premise. 

4. All patriots are voters. 
Some citizens are not voters. 
Therefore, some citizens are not patriots. 

 '''''Worked it out??''''' 
This syllogism is ''valid''. The logic is valid, even though the conclusion may be false. For the first premise might be false. In other words, one may have false premises and a false conclusion, while the logic remains valid. It is also possible to have true premises and a true conclusion but false logic (the conclusion simply does not follow from the premises). 

5. All scientific knowledge is a work of reason. 
All scientific knowledge is true. 
Therefore, all that is true is a work of reason. 

 '''''Found the answer??''''' 
This syllogism is ''invalid''. “All that is true” is distributed in the conclusion, but is undistributed in the second premise. 

6. No oak trees bear fruit. 
No maple trees bear fruit. 
Therefore, no oak trees are maples. 

 '''''Well done!!''''' 
This syllogism is ''invalid''. One cannot conclude anything from two negative premises. The role of the Middle Term is to join the Major and Minor Terms. The Middle Term cannot do this if both premises are negative. 

7. All human action is conditioned by circumstances. 
All human action involves morality. 
Therefore, all that involves morality is conditioned by circumstances (moral relativism). 

 '''''What is your result??''''' 
Yes, this syllogism is ''invalid''. Any term which is distributed in the conclusion must also be distributed in the premises (“All that involves morality” is distributed in the conclusion, but not in the second premise). 

8. All that is good is pleasant. 
All eating is pleasant. 
Therefore, all eating is good. 

 '''''Strike!!''''' 
This syllogism is also invalid. Undistributed Middle Term. 

9. No man is perfect 
Some men are presidents. 
Therefore, some presidents are not perfect. 
'''''Another light question, don't you think?''''' 
This syllogism is ''valid''. 

10. All educated people have worked hard. 
Some students are not educated. 
Therefore, some students have not worked hard. 

 '''''That's right!!''''' 
This syllogism is ''invalid'' because The term “not worked hard” is distributed in the conclusion, but it is undistributed in the first premise. 

===Exercise 2 ===

'''In the following syllogistic arguments the conclusion is missing. Study the two reasons very carefully and complete the syllogism with the conclusion that logically follows. For the solutions, mark the following paragraph (which is seemingly empty) with your mouse. '''

'''''Hint''''': ''Look carefully at the arguments. What is the subject, what is the predicat of the syllogism?''

1.
All fragile things are breakable things. 
Some glasses are fragile things. 
Therefore,... 

 '''''Well done!''''' 
Some glasses are breakable things. 

2.
All mammals are warm-blooded animals. 
All whales are mammals. 
Therefore,... 

 '''''Good job!''''' 
All Whales are warm-blooded animals. 

3.
All flowers are pretty objects. 
All pansies are flowers. 
Therefore,... 

 '''''It was not so difficult, right?''''' 
All pansies are pretty objects. 

4.
All A are B 
Some C are not B. 
Therefore,... 

 '''''Worked it out?''''' 
Some C are not A. 

===Exercise 3===

'''''You are supposed to rewrite the following arguments as standard-form syllogisms and name the mood of each argument. For the more advanced Learner name the figure of the syllogism. Decide if this syllogism is valid or invalid. For the solutions, mark the following paragraph (which is seemingly empty) with your mouse.'''''

''Example:'' 
All mental decisions are things describable by science, but no things describable by
science are uncaused happenings; it follows that no mental decisions are uncaused
happenings.

''Answer:'' 
No things describable by science are uncaused happenings. 
All mental decisions are things describable by science. 
No mental decisions are uncaused happenings. 

This is an EAE-1 syllogism and this syllogism is valid

Now is your turn.

1. Some human is not Athenian, but all Athenians are Greek; it follows that some human is not Greek.

 All Athenians are Greek. 
Some human is not Athenian. 
Therefore, some human is not Greek. 

 This is an AOO-1 syllogism and this sylogism is valid. 

2. All liars are wicked, but not all liars are self deceived; it follows that all wicked are self deceived.

 All liars are self deceived. 
All liars are wicked. 
All wicked are self deceived.

 This is an AAA-3 syllogism and this syllogism is also valid. 

3. Some divine being is human, but no human is omniscient; it follows that some divine being is not omniscient.

 No human is omniscient. 
Some divine being is human. 
Some divine being is not omniscient. 

 This is an EIO-1 syllogism and this syllogism is also valid. 

4. Some natural processes are not free choices, because some natural processes are not
caused occurrences, and no free choices are caused events.

 No free choices are caused occurrences. 
Some natural processes are not caused occurrences. 
Some natural processes are not free choices. 

 This syllogism is invalid. Fallacy of two negative premises. 

===Exercise 4===

Identify the terms; i.e., identify M, P, and S for each one of following six syllogisms, choose the correct answer: 

1.All children are cute. 
All brats are children. 
All brats are cute. 

[[Syllogism1a| a]]) M=brats , P=cute, S=children
[[Syllogism1b| b]]) M=cute , P=children, S=brats
[[Syllogism1c| c]]) M= children , P= cute, S=brats

==Intresting==

The ''Rhinocersos'' by Eugene Ionesco shows many examples of invalid syllogism.

[[wikipedia:Rhinoceros (play)|Rhinoceros]] (French original title Rhinocéros) is a play by Eugène Ionesco, written in 1959. The play belongs to the school of drama known as the Theatre of the Absurd. Over the course of three acts, the inhabitants of a small, provincial French town turn into rhinoceroses; ultimately the only human who does not succumb to this mass metamorphosis is the central character, Bérenger, a flustered everyman figure who is often criticized throughout the play for his drinking and tardiness. The play is often read as a response and criticism to the sudden upsurge of Communism, Fascism and Nazism during the events preceding World War II, and explores the themes of conformity, culture, mass movements, philosophy and morality.

==Quotes==

''"A syllogism is valid (or logical) when its conclusion follows from its premises. A syllogism is true when it makes accurate claims--that is, when the information it contains is consistent with the facts. To be sound, a syllogism must be both valid and true. However, a syllogism may be valid without being true or true without being valid."'' 
(Laurie J. Kirszner and Stephen R. Mandell, The Concise Wadsworth Handbook, 2nd ed. Wadsworth, 2008)

''"It was at this point that the dim beginnings of a philosophy began to invade her mind. The thing resolved itself almost into an equation. If father had not had indigestion he would not have bullied her. But, if father had not made a fortune, he would not have had indigestion. Therefore, if father had not made a fortune, he would not have bullied her. Practically, in fact, if father did not bully her, he would not be rich. And, if he were not rich . . .. She took in the faded carpet, the stained wall-paper, and the soiled curtains with a comprehensive glance. . . . It certainly cut both ways. She began to be a little ashamed of her misery."'' 
P.G. Wodehouse, Something Fresh, 1915)

''"On Meet the Press, . . . [Tim] Russert reminded [George W.] Bush, 'The Boston Globe and the Associated Press have gone through some of their records and said there's no evidence that you reported to duty in Alabama during the summer and fall of 1972.' Bush replied, 'Yeah, they're just wrong. There may be no evidence, but I did report. Otherwise, I wouldn't have been honorably discharged.' That's the Bush syllogism: The evidence says one thing; the conclusion says another; therefore, the evidence is false."'' 
(William Saletan, Slate, Feb. 2004)

"Dr. House: ''Words have set meanings for a reason. If you see an animal like Bill and you try to play fetch, Bill's going to eat you, because Bill's a bear.'' Little Girl: ''Bill has fur, four legs, and a collar. He's a dog.'' Dr. House: ''You see, that's what's called a faulty syllogism; just because you call Bill a dog doesn't mean that he is . . . a dog."'' 
("Merry Little Christmas, House, M.D.)

''"[Andrew] Marvell's "To His Coy Mistress" . . . involves a tripartite rhetorical experience which is argued like a classical syllogism: (1) if we had world enough and time, your coyness would be tolerable; (2) we do not have sufficient world or time; (3) therefore, we must love at a faster rate than gentility or modesty permit. Although he has written his poem in a continuous sequence of iambic tetrameter couplets, Marvell has separated the three elements of his argument into three indented verse-paragraphs, and, more important, he has proportioned each according to the logical weight of the part of the argument it embodies: the first (the major premise) contains 20 lines, the second (the minor premise) 12, and the third (the conclusion) 14."'' 
(Paul Fussell, Poetic Meter and Poetic Form, rev. ed. Random House, 1979)

==References and links==

Hurley, P.,J. (2012). ''A concise introduction to logic''. Wadsworth 

Parry, W.,T. (1991). ''Aristotelian Logic''. State University of New York Press 

http://plato.stanford.edu/entries/aristotle-logic/ 

http://www.mentesenblanco-razonamientoabstracto.com/silogismos-ejercicio1-en.html 

http://online.santarosa.edu/presentation/page/?100919

http://grammar.about.com/od/rs/g/syllogismterm.htm

Syllogism

2013-03-22T11:15:28Z

Anna: /* Intresting */

{{MaterialUnderConstruction}}

=Syllogism=

/ˈsɪləˌdʒɪzəm/

==Definition==

A [[wikipedia:Syllogism|syllogism]] is a logical argument composed of three parts: the major premise, the minor premise, and the conclusion inferred from the premises. 

According to Patrick Hurley a standard-form categorical syllogism is one which meets ''the four conditions''. First of all, the three statements must be standard-form categorical propositions. Second of all, the two occurrences of each term should be the same. What is more, each term must be use in the same sense throughout the argument. And finally the major premise occurs first and it is followed by minor premise and the conclusion is the last one. 
The first condition means that each statement needs a proper quantifier, subject term, copula and predicate term. The second statement is very clear and the third one excludes the possibility of equivocation. It means for instance that if there is a syllogism that contain a word men and it is used in two different senses for example in one term in the sense of human beings in one statement and in the sense of male human beings in another statement, The syllogism would contain then more than three terms and that is why it would be not in standard form. The last condition says that these three statements must be listed in the right order. 

I will help you to understand the syllogism you just need to follow this article step by step.

== Steps==

=== First Step===

First thing that you have to know is the basic structure of syllogism. As you already know the syllogism consists of three propositions : 
#major premise 
#minor premise and 
#conclusion 

in which there appear a total of exactly three categorical terms, each of which is used exactly twice. Each of the premises has one term in common with the conclusion: the major term in the major premise, which forms the predicate of the conclusion, and the minor term in the minor premise, which forms the subject of the conclusion. The categorical term in common in the premises is called the "middle term". For instance:

'''Major premise:''' ''No geese are felines. ''
'''Minor premise:''' ''Some birds are geese. ''
'''Conclusion:''' ''Therefore, Some birds are not felines. ''

In this example you can see that "felines" is the ''major term'' and ''predicate of the conclusion'', "bird" is the ''minor term'' and ''subject of the conclusion'', and "geese" is the ''middle term''.

===Second Step===

It is easier when you try to think of each term as representing a category. For instance "plant" is a category composed of everything that can be described as a plant.

===Third Step===

You can notice that each part is expressed as "Some/all/no S is/are [not] P," and have four possible variation. The universal affirmative (symbolized as A) is expressed as "all S is/are P,". The universal negative (symbolized as E) is expressed as "no S is/are P,". The particular affirmative (symbolized as I) is expressed as "some S is/are P,". The particular negative (symbolized as O) is expressed as "some S is/are not P,". This you can see in the table below: 

'''A''' |All |''S'' |are |''P'' |'''universal affirmatives''' |''All humans are mortal''. 
'''E''' |No |''S'' |are |''P'' |'''universal negatives''' |''No humans are perfect''. 
'''I''' |Some |''S'' |are |''P'' |'''particular affirmatives''' |''Some humans are healthy''. 
'''O''' |Some|''S'' |are not |''P'' |'''particular negatives''' |''Some humans are not clever''. 

('''S''' is a Subject, '''P''' is a Predicate)

The mood classification derives from medieval logicians. The mood of categorical syllogism is a statement of which categorical propositions such as A, E, I or O consist of, placed in the same order in which they occur in the standard form. For instance, if the major premise is an A proposition, the minor premise an O proposition, and conclusion an E proposition, the mood is AOE. Another example: a syllogism with the mood of OAO has an O proposition as its major premise, an A proposition as its minor premise and an O proposition as its conclusion and the like. In order to determine the mood of a categorical syllogism we are first supposed to put the syllogism in the standard form and note the letter name of the statements to the side of each. This is how we create the mood of syllogism, reading the letter for the major premise first, then the letter for the minor premise and finally the letter for the conclusion.

===Fourth Step===

The fourth step is to determine the figure of the syllogism. Depending on whether the middle term serves as subject or predicate in the premises, a syllogism may be classified as one of four possible figures.

There are four different arrangements possible. In the first figure syllogism the middle term is the subject term of the major premise and the predicate term of the major premise. In the second figure, the middle term is the predicate term of both premises. In the third figure, the subject term of both premises and in the last fourth figure, the middle term occurs as the predicate term of the major premise and the subject term of the minor premise. The letter S represents the subject of the conclusion, minor term; P represents the predicate of the conclusion, major term, and M stands for the middle term, and leave out the quantifiers and copulas.

You can click on this link to see the table which illustrate it:

[[File:Figure.pdf|500px]]

===Fifth Step===

For the next step you have to decide if the syllogism is valid. A valid Argument is an argument whose premises are true and then the conclusion has to be true. If a syllogism is valid it is not possible for its premises to be true while its conclusion is false. An example of valid argument can be: There are over seventy students in this classroom; therefore, there are over ten students in this classroom.

==Attention==

You have to be aware that the fallacy of illicit minor and illicit major can occur. A formal fallacy committed in a categorical syllogism that is invalid because its major term is undistributed in the major premise but distributed in the conclusion is called ''illicit major''. The example of this fallacy is in the form All A are B; no C are A. Therefore, no C are B. For instance, "All cats are animals"; "no dogs are cats"; therefore, "no dogs are animals": this syllogism is invalid because the major term "animals" is undistributed in the major premise, but distributed in the conclusion.

Categorical syllogism that is invalid because its minor term is undistributed in the minor premise but distributed in the conclusion committed the fallacy of the ''illicit minor''. An example of this is in the form All A are B; all A are C. Therefore, all C are B. For instance, "All cats are mammals"; "all cats are animals"; therefore, "all animals are mammals": this syllogism is invalid because the minor term "animals" is undistributed in the minor premise (because not all animals are cats), but distributed in the conclusion.

==Tip==

If I awake your interest about the syllogism, and you want to know more details, you can click on this link: [[wikipedia:Syllogism|syllogism]] or read ''A concise introduction to logic'' by Patrick Hurley or ''Aristotelian Logic'' by W. Parry.

==Exercises==

Hier you can check your knowledge about the syllogism. There are different types of exercises. Have fun while doing them.

===Exercise 1===

'''Indicate whether the following arguments are ''valid'' or ''invalid''. If the syllogism is ''invalid'' indicate which rule of logic was violated. For the solutions, mark the following paragraph (which is seemingly empty) with your mouse. '''

'''Hint:''' you can ''first'' think about: what is the middle term of the syllogism. Then what kind of statment is the first permise is that: A, I, E or O, and what kind of statment is the conclusion. 
''Second'' you can check if the middle term is distributed at least once. If it is not, you do not need to proceed further, the syllogism is invalid. 
''Third'', if there are any distributed terms in the conclusion, check to see if those very terms are distributed in the premises. 
''Finally'' check the rest of the rules. If no rules are violated, the syllogism is valid.

1. Nothing easy is worthwhile. 
Nothing good is easy. 
Therefore, nothing good is worthwhile. 

 '''''Perfect!!''''' 
This syllogism is '''invalid'''. No conclusion can be drawn from two negative premises. 

2. All married people know about marriage problems. 
No priests are married people. 
Therefore, no priests know about marriage problems. 

 '''''Correct!!''''' 
This syllogism is '''invalid''' because “Know about marriage problems” is distributed in the conclusion, but is undistributed in the first premise. 

3. Mathematicians know what mathematics is. 
No philosopher is a mathematician. 
Therefore, no philosopher knows what mathematics is. 

 ''Invalid'', '''''Easy one, right??''''' 
“Knows what mathematics is” is distributed in the conclusion, but is undistributed in the first premise. 

4. All patriots are voters. 
Some citizens are not voters. 
Therefore, some citizens are not patriots. 

 '''''Worked it out??''''' 
This syllogism is ''valid''. The logic is valid, even though the conclusion may be false. For the first premise might be false. In other words, one may have false premises and a false conclusion, while the logic remains valid. It is also possible to have true premises and a true conclusion but false logic (the conclusion simply does not follow from the premises). 

5. All scientific knowledge is a work of reason. 
All scientific knowledge is true. 
Therefore, all that is true is a work of reason. 

 '''''Found the answer??''''' 
This syllogism is ''invalid''. “All that is true” is distributed in the conclusion, but is undistributed in the second premise. 

6. No oak trees bear fruit. 
No maple trees bear fruit. 
Therefore, no oak trees are maples. 

 '''''Well done!!''''' 
This syllogism is ''invalid''. One cannot conclude anything from two negative premises. The role of the Middle Term is to join the Major and Minor Terms. The Middle Term cannot do this if both premises are negative. 

7. All human action is conditioned by circumstances. 
All human action involves morality. 
Therefore, all that involves morality is conditioned by circumstances (moral relativism). 

 '''''What is your result??''''' 
Yes, this syllogism is ''invalid''. Any term which is distributed in the conclusion must also be distributed in the premises (“All that involves morality” is distributed in the conclusion, but not in the second premise). 

8. All that is good is pleasant. 
All eating is pleasant. 
Therefore, all eating is good. 

 '''''Strike!!''''' 
This syllogism is also invalid. Undistributed Middle Term. 

9. No man is perfect 
Some men are presidents. 
Therefore, some presidents are not perfect. 
'''''Another light question, don't you think?''''' 
This syllogism is ''valid''. 

10. All educated people have worked hard. 
Some students are not educated. 
Therefore, some students have not worked hard. 

 '''''That's right!!''''' 
This syllogism is ''invalid'' because The term “not worked hard” is distributed in the conclusion, but it is undistributed in the first premise. 

===Exercise 2 ===

'''In the following syllogistic arguments the conclusion is missing. Study the two reasons very carefully and complete the syllogism with the conclusion that logically follows. For the solutions, mark the following paragraph (which is seemingly empty) with your mouse. '''

'''''Hint''''': ''Look carefully at the arguments. What is the subject, what is the predicat of the syllogism?''

1.
All fragile things are breakable things. 
Some glasses are fragile things. 
Therefore,... 

 '''''Well done!''''' 
Some glasses are breakable things. 

2.
All mammals are warm-blooded animals. 
All whales are mammals. 
Therefore,... 

 '''''Good job!''''' 
All Whales are warm-blooded animals. 

3.
All flowers are pretty objects. 
All pansies are flowers. 
Therefore,... 

 '''''It was not so difficult, right?''''' 
All pansies are pretty objects. 

4.
All A are B 
Some C are not B. 
Therefore,... 

 '''''Worked it out?''''' 
Some C are not A. 

===Exercise 3===

'''''You are supposed to rewrite the following arguments as standard-form syllogisms and name the mood of each argument. For the more advanced Learner name the figure of the syllogism. Decide if this syllogism is valid or invalid. For the solutions, mark the following paragraph (which is seemingly empty) with your mouse.'''''

''Example:'' 
All mental decisions are things describable by science, but no things describable by
science are uncaused happenings; it follows that no mental decisions are uncaused
happenings.

''Answer:'' 
No things describable by science are uncaused happenings. 
All mental decisions are things describable by science. 
No mental decisions are uncaused happenings. 

This is an EAE-1 syllogism and this syllogism is valid

Now is your turn.

1. Some human is not Athenian, but all Athenians are Greek; it follows that some human is not Greek.

 All Athenians are Greek. 
Some human is not Athenian. 
Therefore, some human is not Greek. 

 This is an AOO-1 syllogism and this sylogism is valid. 

2. All liars are wicked, but not all liars are self deceived; it follows that all wicked are self deceived.

 All liars are self deceived. 
All liars are wicked. 
All wicked are self deceived.

 This is an AAA-3 syllogism and this syllogism is also valid. 

3. Some divine being is human, but no human is omniscient; it follows that some divine being is not omniscient.

 No human is omniscient. 
Some divine being is human. 
Some divine being is not omniscient. 

 This is an EIO-1 syllogism and this syllogism is also valid. 

4. Some natural processes are not free choices, because some natural processes are not
caused occurrences, and no free choices are caused events.

 No free choices are caused occurrences. 
Some natural processes are not caused occurrences. 
Some natural processes are not free choices. 

 This syllogism is invalid. Fallacy of two negative premises. 

===Exercise 4===

==Intresting==

The ''Rhinocersos'' by Eugene Ionesco shows many examples of invalid syllogism.

[[wikipedia:Rhinoceros (play)|Rhinoceros]] (French original title Rhinocéros) is a play by Eugène Ionesco, written in 1959. The play belongs to the school of drama known as the Theatre of the Absurd. Over the course of three acts, the inhabitants of a small, provincial French town turn into rhinoceroses; ultimately the only human who does not succumb to this mass metamorphosis is the central character, Bérenger, a flustered everyman figure who is often criticized throughout the play for his drinking and tardiness. The play is often read as a response and criticism to the sudden upsurge of Communism, Fascism and Nazism during the events preceding World War II, and explores the themes of conformity, culture, mass movements, philosophy and morality.

==Quotes==

''"A syllogism is valid (or logical) when its conclusion follows from its premises. A syllogism is true when it makes accurate claims--that is, when the information it contains is consistent with the facts. To be sound, a syllogism must be both valid and true. However, a syllogism may be valid without being true or true without being valid."'' 
(Laurie J. Kirszner and Stephen R. Mandell, The Concise Wadsworth Handbook, 2nd ed. Wadsworth, 2008)

''"It was at this point that the dim beginnings of a philosophy began to invade her mind. The thing resolved itself almost into an equation. If father had not had indigestion he would not have bullied her. But, if father had not made a fortune, he would not have had indigestion. Therefore, if father had not made a fortune, he would not have bullied her. Practically, in fact, if father did not bully her, he would not be rich. And, if he were not rich . . .. She took in the faded carpet, the stained wall-paper, and the soiled curtains with a comprehensive glance. . . . It certainly cut both ways. She began to be a little ashamed of her misery."'' 
P.G. Wodehouse, Something Fresh, 1915)

''"On Meet the Press, . . . [Tim] Russert reminded [George W.] Bush, 'The Boston Globe and the Associated Press have gone through some of their records and said there's no evidence that you reported to duty in Alabama during the summer and fall of 1972.' Bush replied, 'Yeah, they're just wrong. There may be no evidence, but I did report. Otherwise, I wouldn't have been honorably discharged.' That's the Bush syllogism: The evidence says one thing; the conclusion says another; therefore, the evidence is false."'' 
(William Saletan, Slate, Feb. 2004)

"Dr. House: ''Words have set meanings for a reason. If you see an animal like Bill and you try to play fetch, Bill's going to eat you, because Bill's a bear.'' Little Girl: ''Bill has fur, four legs, and a collar. He's a dog.'' Dr. House: ''You see, that's what's called a faulty syllogism; just because you call Bill a dog doesn't mean that he is . . . a dog."'' 
("Merry Little Christmas, House, M.D.)

''"[Andrew] Marvell's "To His Coy Mistress" . . . involves a tripartite rhetorical experience which is argued like a classical syllogism: (1) if we had world enough and time, your coyness would be tolerable; (2) we do not have sufficient world or time; (3) therefore, we must love at a faster rate than gentility or modesty permit. Although he has written his poem in a continuous sequence of iambic tetrameter couplets, Marvell has separated the three elements of his argument into three indented verse-paragraphs, and, more important, he has proportioned each according to the logical weight of the part of the argument it embodies: the first (the major premise) contains 20 lines, the second (the minor premise) 12, and the third (the conclusion) 14."'' 
(Paul Fussell, Poetic Meter and Poetic Form, rev. ed. Random House, 1979)

==References and links==

Hurley, P.,J. (2012). ''A concise introduction to logic''. Wadsworth 

Parry, W.,T. (1991). ''Aristotelian Logic''. State University of New York Press 

http://plato.stanford.edu/entries/aristotle-logic/ 

http://www.mentesenblanco-razonamientoabstracto.com/silogismos-ejercicio1-en.html 

http://online.santarosa.edu/presentation/page/?100919

http://grammar.about.com/od/rs/g/syllogismterm.htm