Fast Start on Web Page presentations (for Instructors) martin Thu, 10/16/2014 - 17:20

10/15/14  under construction

[Deriver works in the form either of javascript widgets, which appear directly in a web page viewed through a web browser, or as a downloadable java application, which runs like any other application (usually off the desktop on your computer).]

With the widgets in web pages, it should be fairly clear what the possibilities are. The downloaded application offers more, but at the cost of being more complex.)

Tutorial 22: Symbolizing Relations

Logical System


Tutorial 22 Symbolizing Relations.

The Tutorial

Thus far we have considered only 'monadic' predicates-- our atomic formulas consist of a predicate followed by only one term-- for example, Fx. But in English we regularly encounter dyadic predicates or relations. For example, 'Arthur is taller than Bert' cannot be symbolized with the tools we have used so far; what is needed is a relation to represent ' taller than ...' Txy, say, and then the proposition would be symbolized Tab.



Review of New Material

Logical System


A start can be made in predicate logic by taking apart 'atomic' sentences and by re-phrasing what they have to say in a 'entity-has-property' way.

The constant terms a,b,c...h are used to denote entities, the predicates A,B,C...Z are used to denote properties that these entities have, and these are put together by writing the predicate first followed by the term, for example Gb.

Tutorial 11: Sketch of the second part of the course, and symbolizing sentences using predicate logic.

Logical System


Skills to be acquired in this tutorial:

To start learning how to symbolize sentences using predicate logic.

The Tutorial:

There are many valid arguments which cannot be shown to be valid using sentential logic alone. For example,


Beryl is a philosopher.
All philosophers are wise.
Beryl is wise.


Logical System

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

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

There are five propositional 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 ...'