bergmann

Tutorial 4: Arguments and searching for a counter example

Logical System

8/8/08 10Software

Skills to be acquired in this tutorial:

To learn how to symbolize arguments, and how to judge whether they might be invalid using truth-table methods.

Why this is useful:

We wish to appraise arguments, to do this we have to symbolize them first. Judging the invalidity of arguments by truth-table methods is not particularly important, but it does help to develop skills involving truth and lists of formulas.

Reading

Bergmann[2004] The Logic Book Section 3.5.

Review

Logical System

There is the idea of setting up a code or convention or dictionary between atomic sentences and capital letters.

There are compound sentences, each of which has a main connective which connects its components.

There are five sentential logical connectives:

'∼' which translates back to 'it is not the case that...'

'&' which translates back to '... and ...'

'∨' which translates back to '... or ...'

'⊃' which translates back to 'if... then ...'

'≡' which translates back to '... if and only if ...'

Tutorial 2: Symbolizing compound sentences

Logical System

6/8/07 10 Software

Skills to be acquired in this tutorial:

Symbolizing compound sentences. Learning about logical connectives, and the notion of the main connective. Recognizing different constructions in English which have the same underlying logical form. Paraphrasing the English into a standard form.

Why this is useful:

It is the next step in learning how to symbolize. Main connectives are very important-- they are central to symbolization, they are central to the semantics, and they are central to derivations.

Tutorial 1 Introduction, sketch of course, and symbolizing atomic sentences.

Logical System

7/31/08 10 Software

Skills to be acquired in this tutorial:

To become familiar with the notions of argument, valid, invalid, premise, and conclusion. To learn how to symbolize atomic sentences.

Reading

Bergmann[2004] The Logic Book Chapter 1

Tutorial:

The main role of logic is to assess arguments-- to say whether an individual argument is valid or whether it is invalid. In logic, arguments are taken to consist of two components--premises, and a conclusion.

For example,

Easy Deriver [Bergmann, using Java Applets]

Logical System

Welcome!

These web pages provide an introduction to logic to the level of Propositional and Predicate Calculus.

The focus of the program is on arguments and the question of whether they are valid. Arguments have the form <list of premises> ∴<conclusion>. An argument is valid if and only if it is not possible for all its premises to be true and its conclusion false at one and the same time; an argument which is not valid is invalid.