Logic Atty Miras

7/28/2019 Logic Atty Miras

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Logic (from the Greeklogik)[1]refers to both the study

of modes ofreasoning, which are valid and

which falacious,[2]and also to the use of valid reasoning. In the

latter sense, logic is used in most intellectual activities,

including philosophy and science, but in the first sense is

studied primarily in the disciplines

ofphilosophy, mathematics, semantics, and computer science.

It examines general forms thatarguments may take. In

mathematics, it is the study of valid inferences within

some formal language.[3]Logic is also studied

in argumentation theory.[4]

What is an argument?An argument is, to quote the Monty Python sketch, "aconnected series of statements to establish a definiteproposition". There are three stages to an argument:Premises,inference, and conclusion.Stage one: PremisesOne or more propositions will be are necessary for theargument to continue. They must be stated explicitly. Theyare called the premises of the argument. They are theevidence (or reasons) for accepting the argument and itsconclusions.

Premises (or assertions) are often indicated by phrases suchas "because", "since", "obviously" and so on.(The phrase "obviously" is often viewed with suspicion, as itcan be used to intimidate others into accepting dubiouspremises. If something doesn't seem obvious to you, don't beafraid to question it. You can always say "Oh, yes, you're right,it is obvious" when you've heard the explanation.)Stage two: InferenceThe premises of the argument are used to obtain furtherpropositions. This process is known as inference. In inference,we start with one or more propositions which have beenaccepted. We then derive a new proposition. There arevarious forms of valid inference.The propositions arrived at by inference may then be used in

further inference. Inference is often denoted by phrases suchas "implies that" or "therefore".Stage three: ConclusionFinally, we arrive at the conclusion of the argument, anotherproposition. The conclusion is often stated as the final stage ofinference. It is affirmed on the basis the original premises, andthe inference from them. Conclusions are often indicated byphrases such as "therefore", "it follows that", "we conclude"and so on.Types of argumentThere are two traditional types of argument, deductive andinductive. A deductive argument provides conclusive proof ofits conclusions; if the premises are true, the conclusion must

also be true. A deductive argument is either valid or invalid.A valid argument is defined as one where if the premises aretrue, then the conclusion is true.An inductive argument is one where the premises providesome evidence for the truth of the conclusion. Inductivearguments are not valid or invalid, but we can talk aboutwhether they are better or worse than other arguments. Wecan also discuss how probable their premises are.There are forms of argument in ordinary language which areneither deductive nor inductive. However, this documentconcentrates on deductive arguments, as they are oftenviewed as the most rigorous and convincing.Here is an example of a deductive argument:

Every event has a cause (premise) The universe has a beginning (premise) All beginnings involve an event (premise) This implies that the beginning of the universe

involved an event (inference)

Therefore the universe has a cause (inference andconclusion)

Note that the conclusion of one argument might be a premise

in another argument. A proposition can only be called a

premise or a conclusion with respect to a particularargument; the terms do not make sense in isolation.

PAGES: 1 2 3 4

Arguments and Non-Arguments - 1452Arguments and Non-Arguments

Read pages 1-4 in the textbook. This will give you somearguments. I will expand on these pages in the following lectur

Arguments:

Definition of

1) Linguistic devices used to defend points of vi

2) A combination of statements in no particular order, wpremises), are offered as reasons for another Note: In this class, we will only be examining those arguconclusion. One of the premises will be of the form 'if..then..'containing TWO

3) An argument also means a dispute, for example two peopleThis is NOT the meaning of an argument that weExample:

If its been raining then the ground would be wet. It has

Note that the order of statements is PPC, which m

Example:

John must be a liberal. Anyone who protested the Gulf War mthat

Note that the order of the statements is CWe can change the order and get the

Anyone who protested the Gulf War must be a liberal and Joha
http://en.wiktionary.org/wiki/%CE%BB%CE%BF%CE%B3%CE%B9%CE%BA%CE%AEhttp://en.wiktionary.org/wiki/%CE%BB%CE%BF%CE%B3%CE%B9%CE%BA%CE%AEhttp://en.wiktionary.org/wiki/%CE%BB%CE%BF%CE%B3%CE%B9%CE%BA%CE%AEhttp://en.wikipedia.org/wiki/Logic#cite_note-0http://en.wikipedia.org/wiki/Logic#cite_note-0http://en.wikipedia.org/wiki/Logic#cite_note-0http://en.wikipedia.org/wiki/Reasoninghttp://en.wikipedia.org/wiki/Falacyhttp://en.wikipedia.org/wiki/Logic#cite_note-PopkinStroll1993-1http://en.wikipedia.org/wiki/Logic#cite_note-PopkinStroll1993-1http://en.wikipedia.org/wiki/Logic#cite_note-PopkinStroll1993-1http://en.wikipedia.org/wiki/Philosophyhttp://en.wikipedia.org/wiki/Mathematicshttp://en.wikipedia.org/wiki/Semanticshttp://en.wikipedia.org/wiki/Computer_sciencehttp://en.wikipedia.org/wiki/Argumenthttp://en.wikipedia.org/wiki/Inferencehttp://en.wikipedia.org/wiki/Formal_languagehttp://en.wikipedia.org/wiki/Logic#cite_note-stanford-logic-onthology-2http://en.wikipedia.org/wiki/Logic#cite_note-stanford-logic-onthology-2http://en.wikipedia.org/wiki/Logic#cite_note-stanford-logic-onthology-2http://en.wikipedia.org/wiki/Argumentation_theoryhttp://en.wikipedia.org/wiki/Logic#cite_note-3http://en.wikipedia.org/wiki/Logic#cite_note-3http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?36826http://online.santarosa.edu/presentation/page/?36828http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36827http://online.santarosa.edu/presentation/page/?97479http://online.santarosa.edu/gradebook/?2207mailto:[email protected]://online.santarosa.edu/presentation/schedule?3198http://online.santarosa.edu/http://www.santarosa.edu/http://online.santarosa.edu/presentation/page/?36828http://online.santarosa.edu/presentation/page/?36826http://online.santarosa.edu/presentation/page/?36827http://en.wikipedia.org/wiki/Logic#cite_note-3http://en.wikipedia.org/wiki/Argumentation_theoryhttp://en.wikipedia.org/wiki/Logic#cite_note-stanford-logic-onthology-2http://en.wikipedia.org/wiki/Formal_languagehttp://en.wikipedia.org/wiki/Inferencehttp://en.wikipedia.org/wiki/Argumenthttp://en.wikipedia.org/wiki/Computer_sciencehttp://en.wikipedia.org/wiki/Semanticshttp://en.wikipedia.org/wiki/Mathematicshttp://en.wikipedia.org/wiki/Philosophyhttp://en.wikipedia.org/wiki/Logic#cite_note-PopkinStroll1993-1http://en.wikipedia.org/wiki/Falacyhttp://en.wikipedia.org/wiki/Reasoninghttp://en.wikipedia.org/wiki/Logic#cite_note-0http://en.wiktionary.org/wiki/%CE%BB%CE%BF%CE%B3%CE%B9%CE%BA%CE%AE


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Now it is in the proper order of PPC; Premise, Premise, Conclusion.

Later in this unit, I will discuss how to determine the validity of an argument. Noticing the order of thestatements in an argument will be essential in determining an argument's validity. In order to analyzethe validity of an argument, it is crucial that the argument already comes in PPC order or that we re-sequence the statements into PPC order.

Identification of an argument and it's elements:

1) To identify whether a combination of statements is an argument, try to decide if there is an intent topersuade. Words such as ought and should generally indicate an intent to persuade.

2) To identify the premises and the conclusion in an argument, look for KEYWORDS. A keyword normallycomes BEFORE the premise or conclusion.

Premise Keywords: because, since, for the reason that, for, in as much as, as, and, if...then

Note that the premise keyword 'and' connects 2 premises, one BEFORE it and one AFTER it. Example: "Ifthe temperature is under fifty degrees then you should wear a sweater AND the temperature is underfifty degrees." Premise 1 is 'If the temperature is under fifty degrees then you should wear a sweater' andPremise 2 is 'the temperature is under fifty degrees'.

It is important to note than an if...then statement is just one premise, containing an 'if' part and a 'then'part. Note that the presence of an if...then statement almost always indicates that there is an argumentinvolved.

Conclusion Keywords: so, thus, therefore, consequently, as a result, indicating that, it follows that, we caninfer that, shows that

Example:

If you study hard then youll pass this class. You will study hard. Therefore, you will pass this class.

ANALYSIS: The conclusion is 'you will pass this class' because it follows the conclusion keyword'Therefore'. An argument can contain only one conclusion. Thus, the other statements must be thepremises. Note that the argument is in PPC order, so that no re-sequencing is necessary.

Example:

Since its wrong to kill a human being, it follows that capital punishment is wrong, since capitalpunishment takes the life of a human being.

ANALYSIS: The conclusion is 'capital punishment is wrong' because it follows the conclusion keywords'it follows that'. Thus, the other statements must be the premises. Note that the argument is in PCPorder.

ARGUMENTS WITHOUT KEYWORDS: Some arguments do not have any keywords to help us identifywhich statements are premises and which statement is the conclusion.

Example:

Ken is a biology major. Someone who is taking Biology 222 must be a biology major. Ken is takingBiology 222.

ANALYSIS: There are no keywords present. The conclusion is 'Ken is a biology major' because it issupported by the other statements and is most likely what is intended as the conclusion. If you were tochoose a different statement for the conclusion and say the argument in PPC order then you should seethat the argument doesn't make sense.

ARGUMENTS WITH AN IMPLIED STATEMENT: Sometimes people don't always state the obvious in anargument, and thus some arguments contain an implied premise or an implied conclusion. An impliedstatement in this context is one that is unstated and is assumed to be part of the argument. It is necessaryfor us to find the missing part of the puzzle, that is, to identify what the implied statement is. The implied

statement is usually fairly easy to d

Example: Here is one in which

All Italians like pasta. Hence,

ANALYSIS: The conclusion is 'Maria likes pasta', since it followimplied is a premise that Example: Here is another one in wh

Kelly is in favor of a tax cut. So,

ANALYSIS: The conclusion is 'she must be a Republican', sinWhat is implied is a premise that 'All who

Example: Here is another one in wh

Mary must be a Democrat because ANALYSIS: The conclusion is 'Mary must be a Democrat' andThis premise follows the keyword 'because'. The other premi'All who voted for John Kerry are Democrats'. This is the mimplied.

Example: Here is another one in wh

We ought to pull out of Iraq immediately for the reason thasecurity.

ANALYSIS: The conclusion is 'We ought to pull out of Iraq immany longer jeopardizes our security'. This premise follows thepremise is implied but is not a generalization. It is an if...theand the conclusion, namely, 'If staying in Iraq jeopardizesimmediately'. This is the most logical choice fExample: Here is one where

If you get to school early then you'll find a parking spa

ANALYSIS: Because of the keyword 'and', we should realize ththis keyword. What is implied is the conclusiExample: Here is a tricky one wher

The better the ingredients the better the pizzaANALYSIS: What is implied is a conclusion 'Mambos has a betis not even an argument, but there is an intent to persuadeleaving the conclusion

Example: Here is one where

Surely Joe must be wealthy. Isnt every

ANALYSIS: This argument is more difficult to analyze. 'Isnt ev

'If someone lives in Tiburon then they must be wealthy'. Also What makes the most sense

Premise: If someone lives in Tiberon tPremise (implied): Joe Conclusion: Joe must be wealthy.


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Non-arguments:

1) Unsupported statement(s) of opinion or fact or their combination

Definition of opinion: a belief not based on absolute certainty or positive knowledge; but what seemstrue, valid or probable to one's own mind or judgment. This is tricky because often people will combine aknown fact along with an unsubstantiated statement.

2) Descriptions, narratives or anecdotes

Definition of narrative: the practice of relating stories or accounts.

Definition of anecdote: a short entertaining account of some happening, usually personal or biographical

3) Explanations

Definition of explanation: the act of clearing from obscurity and making intelligible.

[Note: The textbook describes the above non-arguments as being forms of exposition, which is defined asthe setting forth of facts, statements and detailed information.]

Examples:

1) This class began in January and will end in May. The final exam will be comprehensive.

(unsupported statements of fact; There is no conclusion and no intent to persuade)

2) President Bush lied about the weapons of mass destruction in Iraq. He also pushed through his taxcuts to reward his wealthy supporters.

(unsupported statements of a combination of opinion and fact; There is no conclusion and no intent topersuade. Note that although there is a great deal of substantiated facts about weapons of massdestruction NOT being found in Iraq, there are no facts to prove that Bush knew this. In the secondstatement concerning Bush's tax cuts, it is a fact that the tax cuts benefited the very wealthy the most, wedo not have proof that this was done solely as a reward to his wealthy supporters.)

3) We went to Tahoe on our summer vacation. We had a great time. Then we went to Reno and won $25

played the slots. After that, we went to Wine Country and visited the best wineries there.

(narrative; There is no conclusion and no intent to persuade)

4) I was late to class because I couldnt find a parking space.

(explanation; There is no conclusion and no intent to persuade)

Notes about Non-Arguments:

1) Sentences are claimed to be true without showing they are true.2) Takes the truth for granted, that is, assumes there is no doubt on the part of the listener.3) Does not attempt to persuade by offering reasons that support a conclusion.

4) Lacks conclusions keywords and argument keywords such as ought or if...then5) May contain premise keywords, such as because or since.6) Sometimes there is a fine line between an argument and an explanation. You must decide through thecontext.7) The difference between an argument and a non-argument is based on the intent or purpose toestablish the truth. Arguments intend to persuade; Non-arguments do not.8) Non-arguments provide no reason to accept the statements as facts other than the authority of thewriter or speaker.9) Sometimes non-arguments will lead to arguments.

Conclusion about arguments and non-arguments:

A combination of statements are called an argument if theconclusion

A statement or a combination of statements is called a non-with no intent to persuade and without conclusion keywords.

Arguments on the Internet

Arguments from Thinking Straight

Examples:

Determine whether the following are arguments or non-conclusion. Write down your answers and then 1) The class was canceled because of lack of enrollment. Mos2) If a persons desk is organized then their mind is organized

organized.

3) This Thai food is sure hot. Can

4) Since the Gulf War, this committ5) Only adult citizens can vote and Peter is

6) We must begin to develop alternative energy sources, for ostake.

7) Most doctors want to set their own fees. So, doctors are 8) Abortion raises serious moral questions because abortion that involves taking a life raises

9) I dont like big-time college football and I dont like pro fooperiod.

10) Some people are good at math and some

11) Heather didnt come to the party becaus

12) Heather couldnt have come to the party because she w

with him, she

13) Barry doesnt have health insurance. So, hes sure

14) The bigger the burger the better the burger. The burgers a

Logic deals with the analysis and evaluation of arguments

Since arguments are expressed in language, the study of

arguments requires that we should pay carefully attention to

language in which arguments are expressed. If you reflect on

how language is used are everyday life, you can notice that

our ordinary language has different uses.

Language has a variety of functions. By using language we do

various things like stating facts, reporting events giving

orders, singing songs, praying God, making requests, cutting
http://www.freewebs.com/thinkingstraight/Argument.htmhttp://www.freewebs.com/thinkingstraight/Argument.htmhttp://www.freewebs.com/thinkingstraight/Argument.htmhttp://www.freewebs.com/thinkingstraight/Argument.htm


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jokes, asking questions, making promises, greeting friends

and so on. These are wide varieties of language uses. We will

not make any attempt to provide an exhaustive list of

language uses. Rather we shall discuss here a broad

classification of some of the important uses of language. There

are three important uses of language that we shall discuss

here. These are: (a) Descriptive, (b) Emotive, and (c) Directive

uses of language.(a) Descriptive Use of Language:

Language is often used to describe something or to give

information about something. So the descriptive use of

language is also called informative use of language. When a

sentence is used descriptively it reports that something has

some feature or that something lacks some feature. Consider

the following two sentences:

1. Birds have feather.

2. Birds are not mammals.

The first sentence reports that having feather is a feature ofbirds. The second sentence reports that birds do not have

some essential qualities found in mammals. In, either case it

provides information about the world. Both affirmation and

denial about things in the world are examples of descriptive

use of language. The following are some more examples of

language functioning descriptively.

1. Crows are black.

2. Mumbai is not the capital of India

3. A spider has eight legs.

4. Logic is the study of correct reasoning.

5. The 15th of August is Indian Independence Day.

All these above statements happen to be true statements.

However, it should be noted that only true sentences are

instances of informative use of language, but also false

sentences are instances of informative use of language. "A

spider has six legs" is a false statement since spiders in fact

have eight legs. Yet the statement "A spider has six legs", even

though false, is nonetheless an example of descriptive use of

language.

When language functions informatively we can sensibly ask

whether what is asserted is or false. In other words, the

question "Is it true?" can be meaningfully asked of all such

instances. When language is used to affirm or deny any

proposition, its function is informative; Language used to

present arguments serves informative function.

All descriptions of things, events, and their properties and

relations consist of informative discourse. The language of

science is a clear instance of descriptive use of language.

(b) Emotive Use of Language:

Language is often used to express our feelings, emotions or

attitudes. It is used either to express one's own feelings

emotions or attitudes, or evoke certain feelings, emotions or

attitudes someone else, or both.

When one expresses feelings while alone, one is not

expressing it to evoke feelings in others. But very often we

attempt to move others by our expressions of emotions, in all

such cases language is used emotively. Consider the followingutterances:

1. Jai Hind!

2. Cheers!

3. its disgusting!

4. its too bad!

5. its wonderful!

6. Let's win this game!

In appropriate contexts all these can count as instances o

language functioning emotively.

If a sentence is followed by an exclamation mark, then verylikely it is used emotively. The language of poetry also

provides an example of language serving the expressive

function Emotive use is different from descriptive use o

language.

Emotive or expressive discourse is neither true nor false

When language is used emotively, it cannot be characterized

as true or false. We can, however, respond to it by asking

questions such as "Is the person sincere?" and "How should

feel?" Expressive use of language is also different from

directive use of language

(c) Directive Use of Language:

Language is often used to give direction to do or not to do

something. Commands, requests, instructions, questions are

instances of directive use of language. Consider the following

examples:

1. Finish your homework.

2. Wash your clothes.

3. You should wear helmet when riding a scooter.

4. Don't smoke.

5. Are you feeling well?

6. Will you please help me?

In all these above examples language is functioning

directively. Anyone who utters any of these sentences, in a

typical situation, is directing someone to do something or to

respond in an appropriate manner.

In all instances of language functioning directively, we can

meaningfully ask the question "Should I respond?" You wil

notice that directive, discourse, like emotive discourse, is

neither true nor false. But directive discourse, specially the

imperative statements, can figure in some arguments.


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A command such as "Close the window", or an advice such as

"You should wear helmet while riding scooter" is either

obeyed or disobeyed, but it is neither true nor false. Through

commands, advices, and requests are neither true nor false,

these can be reasonable or unreasonable, proper or improper.

These characterizations of imperative statements are

somewhat analogous to characterisation of informative

statements as true or false.Moreover, imperative arguments often imply or presuppose

the truth of some propositions. If I request you to close the

window, my request presupposes the truth of the proposition

that the window is open.

Since reasons can be cited for or against imperative

statements, such statements do occur in imperative

arguments. We are not going to discuss the logic of

imperatives in this book. In our study of logic we shall restrict

our discussion to arguments that are stated in the language

that functions informatively.The study of logic is concerned with language that functions

informatively. So it is important distinguish language that is

informative from language that serves other functions.

There is, however, no mechanical method for distinguishing

informative use of language from language that serves other

functions. Grammatical structure of a sentence often provides

a clue to its function, mere is no necessary connection

between function and grammatical form. We can determine

whether the language in a particular context is functioning

informatively or not by asking "Is this instance of language

being used to make an assertion that is either true or false?" If

the answer is yes'' then it is an instance of informative use of

language.

It should be noted that language, in particular contexts, very

often functions in more than way. One and the same sentence

might have more than one function. For effective

communication language is often used deliberately to serve

multiple functions.

Language used to the expressive function might contain some

relevant information. So also language that is primarily

informative may make use of other functions as well. Most

discourses in our ordinary communication contain elements

from all the three uses of language enumerated above. In logic

restrict our attention to those cases where our discourse is at

least partly informative or descriptive.

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Logic Atty Miras