Review of the 8 Basic Sentential Rules of Inference
10/12/26
Modus Ponens (MP)
p⊃q,
p
∴
q
Modus Tollens (MT)
p⊃q,
~q
∴
~p
Disjunctive Syllogism(DS)
p∨q,
~p
∴
q
or, if desired,
p∨q,
~q
∴
p
Simplication (Simp)
10/12/26
Modus Ponens (MP)
p⊃q,
p
∴
q
Modus Tollens (MT)
p⊃q,
~q
∴
~p
Disjunctive Syllogism(DS)
p∨q,
~p
∴
q
or, if desired,
p∨q,
~q
∴
p
Simplication (Simp)
10/12/26
a) Learning further sentential rules of inference. Carrying out simple sentential derivations using some of the Rules of Inference.
b) Learning elementary Tactics.
Hausman[2007] Logic and Philosophy Chapter 4
Tactics will help you to do derivations.
a)
10/12/26
Learning further sentential rules of inference. Carrying out simple sentential derivations using some of the Rules of Inference.
Hausman[2007] Logic and Philosophy Chapter 4
Thus far we have encountered 3 sentential rules of inference: Simplification, Conjunction, and Addition. If we write these out as forms or patterns, these are the kinds of inferences they permit.
Simplication (Simp)
Review of new material
There are the truth-tables for the connectives...
Negation
F ∼F True False False True
Conjunction
10/12/26
Proving an argument to be valid by displaying a derivation. Carrying out simple sentential derivations using some of the Rules of Inference.
Hausman[2007] Logic and Philosophy Chapter 4
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.
10/12/26
To learn how to symbolize arguments, and how to judge whether they might be invalid using truth-table methods.
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.
Hausman[2007] Logic and Philosophy Chapter 3
10/12/26
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 ...'
'⊃' which translates back to 'if... then ...'
10/12/26
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.
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.
10/12/26
To become familiar with the notions of argument, valid, invalid, premise, and conclusion. To learn how to symbolize atomic sentences.
A. Hausman, H.Kahane, P.Tidman, [2007] Logic and Philosophy Chapters 1, 2.1
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,