propositional

11/27/11

Skills to be acquired in this tutorial:

Proving an argument to be valid by displaying a derivation. Carrying out simple sentential derivations using some of the Rules of Inference.

Reading

Hausman[2007] Logic and Philosophy Chapter 4

The Tutorial:

If you suspect that an symbolized argument might be valid, you should attempt to give a derivation of it.

A derivation is a proof of validity.

11/27/11

Review of new material

There are the truth-tables for the connectives...

Negation

F	∼F
True	False
False	True

Conjunction

Consistent

Invalid

11/27/11 10Software

Quiz 2 Applet

Your browser is not displaying the Deriver applet. Try downloading Deriver itself by clicking on the link elsewhere on the page.

7/3/06

Some of these videos will use different logical symbols to the ones you are familiar with; for example, they use '∧' for 'and' (instead of either '&' or '.'). These minor display unfamilarities do not affect the principles and operations that are being explained.

11/26/11 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

Hausman[2007] Logic and Philosophy Chapter 3

1/24/06

eg Lander or Suber

The problem or issue here lies with the truth table for the conditional (or material implication) ³

11/26/11 10Software

Skills to be acquired in this tutorial:

To learn how compound sentences are true or false depending on the truth or falsity of their component sentences.

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 ...'

'³' which translates back to 'if... then ...'

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