FALLACIES OF PRESUMPTION

FALLACIES OF PRESUMPTION • BEGGING THE QUESTION (PETITIO PRINCIPII) • COMPLEX QUESTION • FALSE DICHOTOMY • SUPPRESSED EVIDENCE • ACCENT OR PROSODY • WORD CONSTRUCTION

FALLACIES OF PRESUMPTION 1. PETITIO PRINCIPII (Begging the question/ REQUEST FOR THE SOURCE) • If the argument fails to prove anything • Reasoning in circles • E.g. • All criminals are immoral; therefore, all criminals are not moral. • Why are you here? Because I’m not there! • All survivors are strong because only… the strong survive. • Sleeping pills work because… they cause people to go to sleep.

2. COMPLEX QUESTION • intended to trap the respondent into acknowledging something that he or she might otherwise not want to acknowledge. • E.g. • Have you stopped cheating your girlfriend? • Where did you hide the cookies you stole?

3. FALSE DICHOTOMY • presumes that an ‘‘either . . . or . . .’’ statement presents mutually exhaustive alternatives • Third alternative is not possible. • E.g. • Either you attend my Philo Class or I’ll be miserable for the rest of my life. I know you don’t want me to be miserable for the rest of my life, so it follows that you’ll attend my class. • Either you buy me a new laptop, or I may not get that grade that you want me to achieve. • Either I continue drinking, or I’ll get fat and you’ll hate to be seen with me.

4. SUPPRESSED EVIDENCE • Presumes (consistency of past experiences is similar to future events) that no important evidence has been overlooked by the premises when in fact it has. • E.g. • Most dogs are friendly and pose no threat to people who pet them. Therefore, it would be safe to pet the little dog that is approaching us now. • During the past four years, Miriam has enjoyed being a student. Therefore, Miriam will probably enjoy being a student for the next fifty years.

FALLACIES OF PRESUMPTION 5. FALLACY OF ACCENT OR PROSODY • Arises from a false accent or from a false emphasis in speech. • A change in a stress of word spells a change in meaning. • E.g. • A dessert is a course of fruit served after the meal; But, a desert is a forsaken region; Therefore, a forsaken region is a course of fruit served after meal. • Recycle clothes and waste paper

FALLACY OF WORD CONSTRUCTION • similarity of meaning from the similar pattern of two words is presumed to be the same on other words. • E.g. • Immortal means not mortal; Immodest means not modest; Therefore, imprinted means… not printed. • The plural of mouse is mice; The plural of louse is lice; Therefore, the plural of house… is hice.

FALLACIES OF AMBIGUITY • EQUIVOCATION • AMPHIBOLY

FALLACY OF AMBIGUITY 1. EQUIVOCATION • A word is used in two different senses in an argument. • A word with different meanings • is used in the same context in a particular argument. • E.g. • No designing persons are to be trusted; But, architects are people who make designs; Therefore, architects are not to be trusted. • A king moves one square in any direction But, Solomon is a king; Therefore, Solomon moves one square in any direction

A tissue is a piece of thin soft absorbent paper. • A cell is a tissue; • A cell is a piece of thin soft absorbent paper. • Cancer is a malignant growth in the body. • The fourth sign of the zodiac is Cancer; • The fourth sign of the zodiac is a malignant growth in the body.

FALLACY OF AMBIGUITY • AMPHIBOLY • Ambiguity in a statement • Arguer misinterprets a statement that is ambiguous and proceeds to draw a conclusion based on this faulty interpretation. • Awkward construction of sentence = • multiple interpretation • E.g. • When depressed, a church is a good place to go. • The tour guide said that standing in Greenwich Village, the Empire State Building could easily be seen. It follows that the Empire State Building is in Greenwich Village.

Take notice: when this sign is under water, this road is impassable • Sign in a maternity ward: “No Children Allowed”

HE: Can I have your name, Miss? • SHE: why, don’t you already have one? • “I would like to buy a clock for my girlfriend with three hands.” • Police: Did you get the plate number? • Witness: No sir, it was bolted to the van.

FALLACIES OF GRAMMATICAL ANALOGY • COMPOSITION • DIVISION

FALLACIES OF GRAMMATICAL ANALOGY • FALLACY OF COMPOSITION (parts) – “C-P” • what is true of the parts of a whole… • is true of the whole thing. • THE WHOLE IS A CLASS! (AND THE PARTS ARE THE MEMBERS OF THE CLASS!) • composition proceeds from the members of the class to the class itself • E.g. • Since every part of a machine is light in weight, the machine as a whole is light in weight. • Each atom in this piece of chalk is invisible. Therefore, the chalk is invisible

FALLACIES OF GRAMMATICAL ANALOGY • FALLACY OF DIVISION (whole) – “D-W” • What is true of the whole • is true of the parts of the whole. • E.g. • All the diamond rings inside the jewelry shop cost over one hundred thousand dollars. This diamond ring which was bought inside the jewelry shop costs over one hundred thousand dollars. • Since a nation is powerful, every individual citizen of that nation is powerful. • A ballpen can write; its parts also can.

FALLACIES OF PRESUMPTION