woensdag 30 maart 2016

The debate continues!

On his blog computer scientist Jeroen Valk posted a thorough reply to my response on his critique of my initial lecture on the scandal of propositional logic. As soon as I have found the time, I will study it carefully and respond to it.

3 opmerkingen:

Bert Morrien zei

Emanuel,

About [1a] p := (Jan is older than 20 years) ∧ q := (Jan is younger than 30 years) → r := (Jan is between 20 and 30 years old).
In the truth table you do not exclude the impossible combination p=O and q=O, where John is both younger than 20 years and older than 30 years. Why?
I think this undermines your claim about the failure of predicate logic.
In general, I don't think considering p and q separately is always legal in p ∧ q → r, in particular where this leads to a paradox.

Emanuel Rutten zei

Bert,

Which truth table in which text are you specifically referring to?

Regard,
Emanuel

Bert Morrien zei

Emaniel,

I referred to http://www.gjerutten.nl/SchandaalLogica_ERutten.pptm ,
in particular those slides which are relevant for
P: (Jan is older than 20 years) and
Q: (Jan is younger than 30 years).
Athough you proved for the genreral case that  (P ∧ Q) → ((P → R) ∨ (P → R)),
I doubt that in this specific case this is valid for P and Q both O, because Jan cannot be 20 years or younger and at the same time 30 years or older.
If you accept that, R is by definition true anyway.
So, in this case it is sufficient to refer to the very first truth table.