bergmann

Topic
Logical System

Example of a difficult derivation

6/1/09 need to check

Topic
Logical System

2013

You may have derivations of your own that you wish to try. Just type, paste, or drag and drop, them into the panel, select your derivation, and click 'Start from selection'. [Often copy-and-paste won't work directly from a Web Page; however, usually drag-and-drop will work!]

You will need to use the correct logical symbols. Here they are

F ∴ F & G ∼ & ∨ ⊃ ≡ ∀ ∃ ∴ (or use the palette to produce them)

Help with Tutorial 25d admin Sat, 01/11/2014 - 01:50
Topic
Logical System

4/24/06

Tutorial 25 Exercises d

Help with Tutorial 25abc admin Sat, 01/11/2014 - 01:50
Topic
Logical System

4/24/06

Tutorial 25 ...

Logical System
1/12/20

You now have the tools to appraise arguments to the level of detail offered by predicate logic.

Let us run through how these might be used with a long and difficult example.

Consider the argument

Tutorial 23: The semantics of relations admin Sat, 01/11/2014 - 01:50
Topic
Logical System

The Tutorial

The semantics of relations proceeds in much the way one would expect-- the new item that has to be taken account of is the order of the terms (because, for example, Tab is not at all the same thing as Tba -- Arthur being taller than Beryl is not the same as Beryl being taller than Arthur).

Interpretation 1

Universe= {a,b}
F={a}

Symbolization Review

Topic
Logical System

11/30/06

[The core of this is from Leblanc and Wisdom [1972] p.117 and f.]

Topic
Logical System

2013

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 '...is taller than ...' Txy, say, and then the proposition would be symbolized Tab.

Tutorial 21: Existential Elimination

Topic
Logical System

2013

Bergmann[2004] The Logic Book Section 10.1.

The Tutorial

Existential Elimination (often called 'Existential Instantiation') permits you to remove an existential quantifier from a formula which has an existential quantifier as its main connective. It is one of those rules which involves the adoption and dropping of an extra assumption (like ∼I,⊃I,∨E, and ≡I).

The circumstance that Existential Instantiation gets invoked looks like this.

Topic
Logical System

2013