Notes for logic

Victoria Int’l College
13
Notes
Introduction to logic
Name: Amit Chaudhary
Semester: 4th

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What is logic?
Logic is the principles and methods used to distinguish correct from incorrect
reasoning. It is the science of valid inference. It is the rational way of drawing or
establishing conclusions. It is the foundation of all mathematics, science, and
reasoning. Logic helps us to identify good argument and understand why they
are good. Similarly, it guides us to identify bad argument and to understand why
they are bad. People use logic in every situation. It is used to solve problems,
troubleshoot, and helps to find mathematical sums. Logic is the way of learning
to think and communicate clearly and coherently. In conclusion, logic is the
justification of our beliefs and the judgments.
Example:
– The increase in CO2 has caused global climate change.
– Humans are responsible for the increase in CO2.
– Humans are responsible for global climate change.
Arguments
Logic and critical thinking are concerned with arguments. An argument is a
collection of propositions, one of which (the conclusion) is supported by the
others (premises). An argument might also be called an inference or reasoning. An
argument is a set of statements connected by a special relationship of
justification; the statements provide evidence for the main claim. Arguments
seek to prove a point; to establish truth of a claim on basis of other claims. An
argument presents logical reasons and evidence to support a viewpoint. The best
arguments are ones with true premises that provide the strongest possible
support for their conclusion. The strongest possible support for a conclusion is
called validity.
Inductive and Deductive Arguments
 INDUCTIVE - reaches a general conclusion from observed specifics.
If we move from specific premise to general conclusion then it is called
inductive argument. It is associated with informal logic.
Example:
– The apple is from the cartoon.
– The apple is very testy.
– So, the apples in the cartoon are testy.
 DEDUCTIVE - begins with a major premise and moves toward a more
specific statement or minor premise.
If we move from general premises to specific conclusion then it is called
deductive argument. It is associated with formal logic.
– All the apples in this cartoon are testy.
Specific
General
General
Specific

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– This apple is from that cartoon.
– So, the apple is testy.
Propositions
Arguments are made up of propositions.
A proposition is a statement that can be expressed as a declarative
sentence. It asserts that something is or is not the case, and thus can be
true or false.
While propositions can be expressed as declarative sentences, they are not to be
equated with declarative sentences. A sentence is a set of symbols (typically
visual or auditory); in certain cases, the proposition is what those symbols mean.
Sentences in different languages, or even different sentences in the same
language, may express the same proposition.
Propositions have different levels of complexity. We can get a sense of these
levels of complexity by distinguishing between simple and compound
propositions.
A proposition is compound if and only if it is a:
(a) A disjunctive proposition: an ‘or’ statement such that the whole
statement is true if and only if at least one of its component statements
are true.
(b) A conjunctive proposition: an ‘and’ statement such that the whole
statement is true if and only if both of its component statements are true.
(c) A hypothetical proposition: an ‘if-then’ statement that is false if and
only if its antecedent is true and its consequent is false.
If a hypothetical is of the form “If p then q,” p is the antecedent and
q is the consequent.
If a statement is not compound, then it is simple.
For example,
All rabbits are mammals.
Bugs Bunny is a rabbit.
 Bugs Bunny is a mammal.
Premises and conclusion
Premises:
Premises are assertions that, when joined together, will lead the reader to
the conclusion. The most important part of any premise is that your
audience will accept it as true. If your audience rejects even one of your
premises, they will likely also reject your conclusion, and your entire
argument will fall apart. When constructing premises, it is essential to

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consider your audience. When you know your audience, you also know
which assertions they will accept and which they will question.
(a) For example, consider the following assertion: “Because greenhouse gases
are causing the atmosphere to warm at a rapid rate...” Is this a solid premise? It
depends on your audience. If your readers are members of an environmental
group, they will accept this premise without qualms. If your readers are oil
company executives, they may reject this premise and your conclusions.
(b) To construct solid premises, you need to consider the rationales and beliefs
of your opponents. What are the “givens” you accept that they do not? What
beliefs lead them to reject those “givens”? Where can two sides of an argument
find common ground? That is where you will find effective premises to reach
your conclusion.
Conclusions:
A conclusion can be any assertion that your readers will not readily accept. A
conclusion must have at least one premise supporting it. The thesis of an
argumentative paper will always contain a conclusion, with the main points or
body paragraphs acting as premises that lead the reader to accept it.
(a) Let’s revisit the previous example, but change the wording slightly:
“Therefore, greenhouse gases are causing the atmosphere to warm at a rapid
rate.” How did changing the first word in the sentence change the function of the
sentence? The meaning of the sentence stays the same, but how we're using it in
our argument has changed. It is now in the form of a conclusion.
(b) You may have heard one of your thesis statements or main arguments
described as “too obvious.” This usually means that your readers already accept
your conclusion without any need for argument. You must also consider your
audience when you are constructing your conclusions.
Recognizing Arguments
Arguments are composed of one or more premises and a conclusion. Premises are
statements offered as reasons for accepting another statement. A conclusion is a
statement supported by reasons.
Distinguishing premises from conclusions is a skill that requires both practice
and close attention to the nuances of language. Here are some tips that will help
you separate premises from conclusions:
1. Look for premise indicators--words like because, since, for, and given that--
that provide clues when premises are being offered.
2. Look for conclusion indicators--words like therefore, thus, hence, and so--
that provide clues when conclusion indicators are being offered.
3. If the passage contains no indicator words, try these two strategies:

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a. Ask yourself, "What claim is the writer or speaker trying to prove?"
That claim will be the conclusion.
b. Try putting the word "therefore" before each of the statements in turn.
The statement it fits best will be the conclusion.
Example:
1. A good society treasures its dissidents and mavericks because it
needs the creative thinking that produces new hypotheses,
expanded means, a larger set of alternatives, and, in general, the
vigorous conversation induced by fresh ideas. (Nel Noddings,
Philosophy of Education, 1995)
Premise: A good society needs the creative thinking that that produces new
hypotheses, expanded means, a larger set of alternatives, and, in general, the
vigorous conversation induced by fresh ideas.
Conclusion: A good society treasures its dissidents and mavericks.
2. Make a will. Otherwise, the state will determine who gets your stuff.
(Andrew Tobias, "Isn't It Time You Faced the Future?" 2001)
Premise: If you don't make a will, the state will determine who gets your stuff.
Conclusion: You ought to make a will.
The word otherwise often functions--as it does here--as premise indicator.
3. With what group do I belong? I am with those who would be pleased
to be refuted if I should say anything that is not true, and pleased to
be the refuter of anyone who should say anything that is not true--
more pleased, in fact, to be refuted than to refute. I think that's a
greater good, you see, insofar as it's a greater good to be relieved of a
great evil than to relieve another of the same. (Socrates, in Plato's
Gorgias)
Premise: It is a greater good to be relieved of a great evil than to relieve
another of the same.
Conclusion: It is a greater good to be refuted than to refute.
In this passage, the premise indicator "insofar as" helps us to identify the
premise.
Notice that the first two sentences aren't strictly part of the argument. Their
function, instead, is to provide background or contextual information
necessary to understand the argument.
4. Good sense is of all things in the world the most equally distributed,
for everybody thinks himself so abundantly provided with it that

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even those most difficult to please in all other matters do not
commonly desire more of it than they already possess.
Premise: Even those most difficult to please in all other matters do not
commonly desire more good sense than they already possess.
Conclusion: Good sense is of all things in the world the most equally distributed.
5. Forbear to judge, for we are sinners all.
Premise: We are sinners all.
Conclusion: You should not judge.
6. Today’s first year college students have lived the external
appearances of an adult life for many more years than their
counterparts 50 years ago did. [Therefore,] what we have
traditionally associated with the intellectual awakening during
childhood years must now occur in the high school.
Premise: Today’s first year college students have lived the external appearances
of an adult life for many more years than their counterparts 50 years ago did.
Conclusion: What we have traditionally associated with the intellectual
awakening during childhood years must now occur in the high school.
7. Thomas Aquinas argued that human intelligence is a gift from God
and therefore to ‘apply human intelligence to understand the world
is not an affront to God, but is pleasing to him.’
Premise: Human intelligence is a gift from God.
Conclusion: To apply human intelligence to understand the world is not an
affront to God, but is pleasing to him.
8. Standardized tests have a disparate racial and ethnic impact; white
and Asian students score, on average, markedly higher than their
black and Hispanic peers. This is true for fourth-grade tests, college
entrance exams, and every other assessment on the books. If a racial
gap is evidence of discrimination, then all tests discriminate.
Premise: White and Asian students score markedly higher than black and
Hispanic students on fourth-grade standardized tests, college entrance exams,
and every other assessment on the books.
Premise: Standardized tests have a disparate racial and ethnic impact.
Conclusion: If a racial gap is evidence of discrimination, then all tests
discriminate.

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Argument vs Explanation
If you want to communicate with someone in order to get your point across, you
will probably end up using many definitive statements backed up by factual
statements. These statements can be based on observation, established facts, or
proofs. Without even consciously thinking about it, we are always using this
methodology in our conversations. These conversations are therefore riddled
with arguments and explanations. While the two terms are often erroneously
used interchangeably and explanations can be used to bolster arguments, there
are many differences between arguments and explanations.
1. Definition of an Argument and an Explanation
Argument – Argument has a number of different definitions. Essentially, it is a
line of logic that is presented in order to support the veracity of a statement.
Argument has combative connotations, but an argument does not have to be
belligerent.
Explanation – Explanation is used to clarify and explicate a statement. Its aim is
to make the listener understand the statement rather than persuade him to
accept a certain point of view.
2. Example of an Argument and an Explanation
Argument - one person wants to convince the other person that it is going to snow
tomorrow. He will cite predictions from the weather station, as well as the clouds
visible on the horizon, the damp chill in the air, and the squirrels furiously hiding
their nuts.
Explanation- one both people agree is it going to snow tomorrow because, they
say, there is a cold front coming in and the air feels damp.
In both cases, the example of snow is used, but note that the argument is trying
to convince someone of the truth of their statement, whereas with the
explanation, it is not a matter of if the statement is true, but why it is true.
3. Uses of Arguments and Explanations
Arguments- Arguments are used in a variety of professional and academic
applications. For instance, a debate club will take on both sides of an argument and
strive to prove each one is right. Arguments are also used by lawyers to convince
the jury of the defendant’s guilt or innocence. Diplomats will approach a
negotiating table with a certain argument in mind. Entrepreneurs will present
potential backers with an argument in support of their business model.

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Explanations- Explanations are used all the time in the classroom to put across
new items to students. Giving directions is a form of explanation. You will also find
explanations included with most new purchases, especially those with some
assembly required. When the aforementioned entrepreneur is presenting an
argument about his business model, he may be asked to explain how it all works.
In summary, then, an argument is a piece of reasoning in which the reason is
intended to provide evidence for accepting a doubted conclusion. An explanation
is a piece of reasoning in which the reason is intended to provide a cause for an
already accepted conclusion.
It is sometimes said that rational inquiry aims at two things: knowledge and
understanding. We can now say that argument and explanation are the reasoning
tools that we use to accomplish these two goals. Argument attempts to establish
knowledge by giving evidence that reduces doubt. Explanation attempts to
establish understanding by supplying causal connections between accepted facts.
Summary:
1. Arguments and explanations are both used to get the point across when
speaking or writing.
2. Arguments are persuasive and seek to make people understand that
something is true, whereas explanations start with the assumption of
truthfulness and tell why or how the statement has come into being.
3. Both arguments and explanations have wide application in education and
business, but arguments are used for persuasion and explanations are used for
clarification.
Validity of arguments
An argument is valid if and only if the truth of its premises entails the truth of its
conclusion and each step, sub-argument, or logical operation in the argument is
valid. Under such conditions it would be self-contradictory to affirm the
premises and deny the conclusion. The corresponding conditional of a valid
argument is a logical truth and the negation of its corresponding conditional is a
contradiction. The conclusion is a logical consequence of its premises.
An argument that is not valid is said to be "invalid".
An example of a valid argument is given by the following well-known syllogism
(also known as modus ponens):
All men are mortal.
Socrates is a man.
Therefore, Socrates is mortal.

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What makes this a valid argument is not that it has true premises and a true
conclusion, but the logical necessity of the conclusion, given the two premises.
The argument would be just as valid were the premises and conclusion false. The
following argument is of the same logical form but with false premises and a false
conclusion, and it is equally valid:
All cups are green.
Socrates is a cup.
Therefore, Socrates is green.
No matter how the universe might be constructed, it could never be the case that
these arguments should turn out to have simultaneously true premises but a
false conclusion. The above arguments may be contrasted with the following
invalid one:
All men are mortal.
Socrates is mortal.
Therefore, Socrates is a man.
In this case, the conclusion does not follow inescapably from the premises. All
men are mortal, but not all mortals are men. Every living creature is mortal;
therefore, even though both premises are true and the conclusion happens to be
true in this instance, the argument is invalid because it depends on an incorrect
operation of implication. Such fallacious arguments have much in common with
what are known as howlers in mathematics.
A standard view is that whether an argument is valid is a matter of the
argument's logical form. Many techniques are employed by logicians to represent
an argument's logical form. A simple example, applied to two of the above
illustrations, is the following: Let the letters 'P', 'Q', and 'S' stand, respectively, for
the set of men, the set of mortals, and Socrates. Using these symbols, the first
argument may be abbreviated as:
All P are Q.
S is a P.
Therefore, S is a Q.
Similarly, the third argument becomes:
All P are Q.
S is a Q.
Therefore, S is a P.
An argument is formally valid if its form is one such that for each interpretation
under which the premises are all true, the conclusion is also true. As already
seen, the interpretation given above (for the third argument) does cause the
second argument form to have true premises and false conclusion (if P is a not
human creature), hence demonstrating its invalidity.
Validity of statements
A statement can be called valid, i.e. logical truth, if it is true in all interpretations.

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DIAGRAMMING, SUMMARIZING, AND PARAPHRASING
ARGUMENTS
I. Analyzing Arguments
A. There are two techniques for analyzing arguments.
1. Paraphrasing arguments involves “setting for the arguments (the one in prose)
and the propositions in clear language and logical order.”1
2. Diagraming arguments involves the use of “spatial relations in two
dimensions”2 for the purposes of clarifying both the content and general flow of
an argument in prose.
Paraphrasing Arguments
• A paraphrase is fundamentally about making the argument of a passage
more easily recognizable, thus a good paraphrase will:
– Use premise- and conclusion-indicators
– Clearly answer the question-and-answer test
– Use common argument forms
– Balance faith and charity
– Add important hidden argument-parts, including contextual clues
Why paraphrase?
• Paraphrasing is the basis of note-taking.
– In an overwhelming majority of cases, the only notes you need to
take are those that pertain to an author’s argument.
– Note-taking is the most important transition from reading to
writing.
• Paraphrasing is the basis of clear writing.
– If you can write good paraphrases, you can write clear sentences,
paragraphs, and papers.
Other paraphrasing strategies: Overview
• Order propositions in an intuitive manner
• Simplify the language of the original text
• Eliminate irrelevant propositions
• Provide uniformity of terms and language
• Plus two more to be discussed next class…
– Identify important intermediate conclusions
– Distinguish independent from dependent premises
• A good paraphrase should list the premises in an order which makes the
structure of the argument clear, minimally in standard form;
– Standard form:
• Premise 1
• Premise 2
• …
• Premise n
• Conclusion
 A good paraphrase should simplify the language of the original text, by
trading out more elliptical and counterintuitive language for more
concrete and concise language.

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 A good paraphrase should eliminate irrelevant propositions. A proposition
is irrelevant if it is neither a premise nor a conclusion of an argument
What does paraphrasing accomplish?
 Paraphrasing helps clarify the argument in prose. (we’ve already noted
this)
 Paraphrasing helps one discern the nature of the inference the argument
is using.
 Paraphrasing can also help one see what premises were assumed, or not
explicitly stated in the prose-style presentation of the argument.
 Paraphrasing also helps prep one for a proper evaluation of the
argument.
Examples:
1. The Pistons did not lose because of the lack of ability. They are an
all-around better team. They lost because of the law of averages.
They will beat the Spurs every two times out of three. When you
examine the NBA Finals, that is exactly how they lost the seventh
because that would have been three out of three. The Spurs will beat
the Pistons one out of three. It just so happens that, that one time
was the final game, because the Pistons had already won two in a
row.
Argument 1:
• Either the Pistons lost because they are inferior to the Spurs
or because of the law of averages.
• The Pistons are better than the Spurs.
•  The Pistons lost the NBA Finals because of the law of
averages.
Argument 2:
• The Pistons will beat the Spurs 2 of 3 times; the Spurs will
beat the Pistons 1 of 3 times.
• The Pistons had won Games 5 and 6 of the Finals—two in a
row, so if they had won the final game they would have won
3 of 3.
•  The Pistons lost the NBA Finals because of the law of
averages.
2. Racially diverse nations tend to have lower levels of social support
than homogeneous ones. People don’t feel as bound together when
they are divided on ethnic lines and are less likely to embrace
mutual support programs. You can have diversity or a big welfare
state. It’s hard to have both.
 If a nation is diverse, then people don’t feel bound together.
 If people don’t feel bound together, then they are less likely to embrace
large scale social programs.

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  If a nation is diverse, then it is less likely to embrace large scale social
programs.
Diagraming Arguments
“To exhibit the structure of an argument it is sometimes useful to represent it
graphically, to diagram it.”5
Sometimes a diagram is more useful when all of the premises and conclusions
are stated explicitly, but in a way that is rather complicated.
Steps toward proper diagraming:
 Read the passage carefully.
 Identify each claim and number them.
 Provide missing parts if needed.
 Determine relation of claims and diagram.
a) Draw in the circled numbers that stand in for coordinate premises at the same
height on your page.6
b) Draw in the conclusion of the argument below the circled numbers
representing the coordinate premises.
c) If the premises of the argument both independently support the conclusion, all
one needs to do next is draw arrows starting from each premise to the
conclusion (see page 23 in the textbook).
d) If the premises of the argument support the conclusion only when understood
in light of one another (as a conjunction perhaps), then one needs to draw a
horizontal line which extends out to each premise that jointly supports the
conclusion, and then one should draw an arrow from the middle of that
horizontal line to the conclusion in the diagram.
e) If there is more than one conclusion, and several premises, sometimes both
conclusions may be supported by the plurality of premises in which case your
diagram will look like that one on page 25 of the textbook.
f) Because “…the same proposition can serve as a premise, where it occurs as an
assumption in an argument; or as a conclusion, where it is claimed to follow from
other propositions assumed in an argument. ‘Premise’ and ‘conclusion’ are
always relative terms.”7
g) Occasionally, one will encounter paragraphs in which there are multiple
arguments, and yet there are stand-alone premises which support differing
conclusions. In such a case, one’s diagram should look like that on page 27 (see
the bottom of the page).
Examples:

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1. Since Mary visited a realtor and her bank’s mortgage department, she
must be planning on buying a home.
Step 1. Number each statement
And note each indicator word.
Since (1) Mary visited a realtor and (2) her bank’s mortgage department, (3) she
must be planning on buying a home.
Step 2. Which of the claims is the conclusion? Which are premises?
Step 3. Use arrows to represent the intended relationship between the claims.
In this case the premises are independent. Even though the combined force of
both premises makes the argument stronger, either premise could stand alone
in supporting the conclusion.
2. Sandra can’t register for her classes on Wednesday. After all, Sandra is a
sophomore and sophomore registration begins on Thursday.
Step #1. Identify each claim and note any indicator words that might help
identify premise(s) and conclusion(s).
(1) Sandra can’t register for her classes on Wednesday. After all, (2) Sandra is
a sophomore and (3) sophomore registration begins on Thursday.
Step #2. Use arrows to show the relationships between the claims in the
argument.
These are linked premises since both (in conjunction) are necessary to prove
the conclusion.
3. Pool maintenance can cost hundreds of dollars a year and we really don’t
have that kind of money. So, I don’t think we should put a pool in this
summer. Besides, pools pose a real drowning danger to small children.
(1)
(2) (3)(+)
(1) (2)
(3)

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Step #1. The first task is to analyze the argument. Decide what the various
claims are and begin to decide which premises are and which conclusions
are. Number the claims and note any indicator words.
(1) Pool maintenance can cost hundreds of dollars a year and (2) we really
don’t have that kind of money. So, (3) I don’t think we should put a pool
in this summer. Besides, (4) pools pose a real drowning danger to small
children.
Step #2. Use arrows to represent the argument
3. You’ve often complained that mainstream television doesn’t have
quality programming, so I think you should support public
broadcasting. Besides, you watch PBS all the time and fair is fair.
Since support means money, you should write a check to PBS
immediately.
(1)You’ve often complained that mainstream television doesn’t have quality
programming, so (2) I think you should support public broadcasting. Besides (3),
you watch PBS all the time and (4) fair is fair. Since (5) support means money,
(6) you should write a check to PBS immediately.
Reasoning:
Reasoning is the set of processes that enables us to go beyond the information
given. Reasoning is just the process of making certain statements, which we call
reasons, in support of other statements, which we call conclusions.
Premises 1 and 2 are linked.
While premise 1 could stand
alone, premise 2 can’t.
Premise 4 is independent.
It could be offered alone as
support for the conclusion.
(1) (2)
(3)
(+)
(4)
(1)
(2)
(3) (+) (4)
(5)
(6)
(+)

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Functions of Language
The formal patterns of correct reasoning can all be conveyed through ordinary
language, but then so can a lot of other things. In fact, we use language in many
different ways, some of which are irrelevant to any attempt to provide reasons
for what we believe. It is helpful to identify at least three distinct uses of
language:
Informative use of language:
The informative use of language involves an effort to communicate some content.
When I tell a child, "The fifth of May is a Mexican holiday," or write to you that
"Logic is the study of correct reasoning," or jot a note to myself, "Jennifer—555-
3769," I am using language informatively. This kind of use presumes that the
content of what is being communicated is actually true, so it will be our central
focus in the study of logic.
Expressive use of language
An expressive use of language, on the other hand, intends only to vent some
feeling, or perhaps to evoke some feeling from other people. When I say, "Friday
afternoons are dreary," or yell "Ouch!" I am using language expressively.
Although such uses don't convey any information, they do serve an important
function in everyday life, since how we feel sometimes matters as much as—or
more than—what we hold to be true.
Directive uses of language
Finally, directive uses of language aim to cause or to prevent some overt action
by a human agent. When I say "Shut the door," or write "Read the textbook," or
memo myself, "Don't rely so heavily on the passive voice," I am using language
directively. The point in each of these cases is to make someone perform (or
forswear) a particular action. This is a significant linguistic function, too, but like
the expressive use, it doesn't always relate logically to the truth of our beliefs.
Notice that the intended use in a particular instance often depends more on the
specific context and tone of voice than it does on the grammatical form or
vocabulary of what is said. The simple declarative sentence, "I'm hungry," for
example, could be used to report on a physiological condition, or to express a
feeling, or implicitly to request that someone feed me. In fact, uses of two or
more varieties may be mixed together in a single utterance; "Stop that," for
example, usually involves both expressive and directive functions jointly. In
many cases, however, it is possible to identify a single use of language that is
probably intended to be the primary function of a particular linguistic unit.
British philosopher J. L. Austin developed a similar, though much more detailed
and sophisticated, nomenclature for the variety of actions we commonly perform
in employing ordinary language. You're welcome to examine his theory of speech
acts in association with the discussion in your textbook. While the specifics may
vary, some portion of the point remains the same: since we do in fact employ
language for many distinct purposes, we can minimize confusion by keeping in
mind what we're up to on any particular occasion.
Literal and Emotive Meaning

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Even single words or short phrases can exhibit the distinction between purely
informative and partially expressive uses of language. Many of the most common
words and phrases of any language have both a literal or descriptive meaning
that refers to the way things are and an emotive meaning that expresses some
(positive or negative) feeling about them. Thus, the choice of which word to use
in making a statement can be used in hopes of evoking a particular emotional
response.
This is a natural function of ordinary language, of course. We often do wish to
convey some portion of our feelings along with information. There is a good deal
of poetry in everyday communication, and poetry without emotive meaning is
pretty dull. But when we are primarily interested in establishing the truth—as
we are when assessing the logical merits of an argument—the use of words
laden with emotive meaning can easily distract us from our purpose.
Kinds of Agreement and Disagreement
In fact, an excessive reliance on emotively charged language can create the
appearance of disagreement between parties who do not differ on the facts at all,
and it can just as easily disguise substantive disputes under a veneer of emotive
agreement. Since the degrees of agreement in belief and attitude are
independent of each other, there are four possible combinations at work here:
Agreement in belief and agreement in attitude: There aren't any problems in
this instance, since both parties hold the same positions and have the same
feelings about them.
Agreement in belief but disagreement in attitude: This case, if unnoticed, may
become the cause of endless (but pointless) shouting between people whose
feelings differ sharply about some fact upon which they are in total agreement.
Disagreement in belief but agreement in attitude: In this situation, parties may
never recognize, much less resolve, their fundamental difference of opinion,
since they are lulled by their shared feelings into supposing themselves allied.
Disagreement in belief and disagreement in attitude: Here the parties have so
little in common that communication between them often breaks down entirely.
It is often valuable, then, to recognize the levels of agreement or disagreement at
work in any exchange of views. That won't always resolve the dispute between
two parties, of course, but it will ensure that they don't waste their time on an
inappropriate method of argument or persuasion.
Emotively Neutral Language
For our purposes in assessing the validity of deductive arguments and the
reliability of inductive reasoning, it will be most directly helpful to eliminate
emotive meaning entirely whenever we can. Although it isn't always easy to
achieve emotively neutral language in every instance, and the result often lacks
the colorful character of our usual public discourse, it is worth the trouble and

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insipidity because it makes it much easier to arrive at a settled understanding of
what is true.
In many instances, the informal fallacies we will consider next result from an
improper use of emotionally charged language in the effort to persuade someone
to accept a proposition at an emotional level, without becoming convinced that
there are legitimate grounds for believing it to be true.

Notes for logic

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Notes for logic