Further Immediate Inferences: Categorical Equivalences

Slides:



Advertisements
Similar presentations
Deductive Arguments: Categorical Logic
Advertisements

Logic Use mathematical deduction to derive new knowledge.
Operations (Transformations) On Categorical Sentences
1 Philosophy 1100 Title:Critical Reasoning Instructor:Paul Dickey Website:
© by Kenneth H. Rosen, Discrete Mathematics & its Applications, Sixth Edition, Mc Graw-Hill, 2007 Chapter 1: (Part 2): The Foundations: Logic and Proofs.
Critical Thinking Lecture 9 The Square of Opposition By David Kelsey.
EDUCTION.
CSE (c) S. Tanimoto, 2008 Propositional Logic
Categorical Syllogisms Always have two premises Consist entirely of categorical claims May be presented with unstated premise or conclusion May be stated.
1 Indirect Argument: Contradiction and Contraposition.
Immediate Inference Three Categorical Operations
Proof by Deduction. Deductions and Formal Proofs A deduction is a sequence of logic statements, each of which is known or assumed to be true A formal.
Copyright © Curt Hill Rules of Inference What is a valid argument?
CSE 755, part3 Axiomatic Semantics Will consider axiomatic semantics (A.S.) of IMP: ::=skip | | | | ; | | Only integer vars; no procedures/fns; vars declared.
CATEGORICAL PROPOSITIONS, CHP. 8 DEDUCTIVE LOGIC VS INDUCTIVE LOGIC ONE CENTRAL PURPOSE: UNDERSTANDING CATEGORICAL SYLLOGISMS AS THE BUILDING BLOCKS OF.
Philosophy 148 Chapter 7. AffirmativeNegative UniversalA: All S are PE: No S is P ParticularI: Some S is PO: Some S is not P.
Tautologies, contradictions, contingencies
Chapter 18: Conversion, Obversion, and Squares of Opposition
Strict Logical Entailments of Categorical Propositions
4 Categorical Propositions
Critical Thinking Lecture 9 The Square of Opposition
Chapter 13: Categorical Propositions. Categorical Syllogisms (p. 141) Review of deductive arguments –Form –Valid/Invalid –Soundness Categorical syllogisms.
Chapter 19: Living in the Real World. Introductory Remarks (p. 190) The joy and misery of ordinary English is that you can say the same thing in many.
CS104:Discrete Structures Chapter 2: Proof Techniques.
Logical Agents Chapter 7. Outline Knowledge-based agents Propositional (Boolean) logic Equivalence, validity, satisfiability Inference rules and theorem.
CS-7081 Application - 1. CS-7082 Example - 2 CS-7083 Simplifying a Statement – 3.
Logical Agents. Outline Knowledge-based agents Logic in general - models and entailment Propositional (Boolean) logic Equivalence, validity, satisfiability.
Simple Logic.
Chapter 1 Logic and Proof.
2. The Logic of Compound Statements Summary
Digital Logic & Design Adil Waheed Lecture 02.
Polynomials and Polynomial Functions
Types CSCE 314 Spring 2016.
Propositional Logic.
Argument An argument is a sequence of statements.
Digital Logic & Design Dr. Waseem Ikram Lecture 02.
A1 Algebraic manipulation
CHAPTER 1.3 Solving Equations.
Exponents Scientific Notation
Today’s Topics Introduction to Predicate Logic Venn Diagrams
Mathematics for Computing
Fundamentals & Ethics of Information Systems IS 201
MAT 105 FALL 2008 Review of Factoring and Algebraic Fractions
1.4 Predicates and Quantifiers
4.1 The Components of Categorical Propositions
Categorical Propositions
Double Negatives.
Philosophy 1100 Class #8 Title: Critical Reasoning
Critical Thinking Lecture 9 The Square of Opposition
CS201: Data Structures and Discrete Mathematics I
Truth Trees.
Logic Use mathematical deduction to derive new knowledge.
Digital Logic & Design Lecture 02.
C3 Chapter 5: Transforming Graphs
Philosophy 1100 Title: Critical Reasoning Instructor: Paul Dickey
How do we categorize and make sense of data?
MINTERMS and MAXTERMS Week 3
(1.4) An Introduction to Logic
Lecture 2: Propositional Equivalences
“Only,” Categorical Relationships, logical operators
Discrete Mathematics CMP-200 Propositional Equivalences, Predicates & Quantifiers, Negating Quantified Statements Abdul Hameed
Binary to Decimal Conversion
Axiomatic Semantics Will consider axiomatic semantics (A.S.) of IMP:
Methods of Proof Chapter 7, second half.
Introductory Concepts
ECE 352 Digital System Fundamentals
CS201: Data Structures and Discrete Mathematics I
Chapter 3 – Describing Logic Circuits
Logical truths, contradictions and disjunctive normal form
Algebra and Indices.
Presentation transcript:

Further Immediate Inferences: Categorical Equivalences Chapter 5.3 Further Immediate Inferences: Categorical Equivalences

It’s easier than it looks. General considerations: All terms have term complements, which consist of everything that is not in the class (i.e., everything that, when considered with the class itself, “completes” or “fills up” the universe of all things). Term complements are indicated by a bar over the term. The ‘xy’ in Axy, Exy, Ixy, Oxy are just variables (place holders) to refer to general cases of the subjects and predicates, respectively, each proposition type. As in normal, informal speech, there are different, equivalent ways of saying things to clarify what one means; similarly, there are different, equivalent ways of expressing each of the categorical proposition types to clarify what one means. The different, equivalent ways of expressing those propositions are the results of three processes: Conversion Obversion, and Contraposition Contraposition, conversion or obversion?

Conversion Only E and I propositions can be converted successfully. Converting an A or O proposition is a logical error (except for conversion by limitation) Accomplished in one step Reverse the subject/predicate order. xy  yx Hence, Exy  Eyx, etc. No dogs are reptiles.  No reptiles are dogs.

Contraposition Only A and O propositions can be contraposed. Contraposing an E or I proposition is a logical error (except for contraposition by limitation). Accomplished in two steps Reverse the subject/predicate order. xy  yx Change each class to its complement. yx  (not-y)(not-x) Hence, Axy  A(not-y)(not-x). All dogs are mammals.  All non-mammals are non-dogs.

Handy demonic devices? convErsIon contrApOsition Irrelevant appeal? “Hey! Look at what I can do!” “Yeah, but what has that got to do with anything?” “He’s got a point, you know.”

The Obversion Two-Step Fr. ob “against” + vertere “to turn”; hence, a proposition seemingly “turned against” itself. Propositions of any type (A, E, I, O) can be obverted successfully, i.e., they are equivalent in meaning to the original proposition. Accomplished in two steps Change quality (from affirmative to negative, or vice versa) A  E, E  A; I  O, O I Change the predicate to its complement xy  x(not-y); x(not-y)  x(not-not-y) (a.k.a. ‘y’) Hence, Axy  Ex(not-y), etc. All dogs are mammals.  No dogs are non-mammals. Obversion Two-Step = Star Trek meets Monty Python The Obversion Two-Step

FYI You can run any proposition through all its possible permutations in four moves (usually beginning with obversion) and obtaining the original proposition on the final move--a handy way of checking whether you’ve done everything correctly. E.g., A obverts to E, convert the E, obvert to A, contrapose to original A Axy  Ex(-y)  E(-y)x  A(-y)(-x)  Axy Four moves = Trinity/Millsap football laterals All dogs are mammals.  No dogs are non-mammals.  No non-mammals are dogs.  All non-mammals are non-dogs.  All dogs are mammals. (original prop.)

Negatives Negativity can take different forms. Analytic: not, no, none, nothing, etc. Synthetic: un-, in-, im-, dis-, etc. Negativity can indicate different things. How classes relate (I.e., E or I) The “presence” of complements A syntactic convolution: “none but . . .,” etc. A contradiction: “It is false that . . . ,” etc.

Dealing with negatives If there are any simple operations that can be performed as a result of double negation, do so. Consider whether and how the negative affects the “quality” (positivity v. negativity) of the proposition. If there appears to be a contradiction, transform the proposition as demonstrated in the Square of Opposition. If there still appears to be a reference to a complementary class, indicate it via bars (recalling that, in this case as well, “two ‘wrongs’ do make a ‘right’”). Nixon’s Law: If two wrongs don’t make a right, try three. 5. Apply as appropriate the operations of categorical equivalence: obversion AND conversion or contraposition.