# Need Help with understanding Deductive Arguments

kennethamy

Tue 10 Nov, 2009 07:57 am
@Emil,
Emil;102682 wrote:

"An illegitimate step"? Why should it have a name?

I think the word you are looking for is "conversion".

Emil

Tue 10 Nov, 2009 08:28 am
@Michel,
Michel;102693 wrote:
conversation is but there is a word within logic called converse. Yet that has does not allow you to move from P→Q to Q→P. The converse, in this instance, is just redirecting the order of the letters. From the converse of P→Q is Q→P which logically identical to P→Q's inverse, ~P→~Q
this resource for symbols.

---------- Post added 11-10-2009 at 03:31 PM ----------

VideCorSpoon;102694 wrote:
You are quite right about that, it is better late than never. The best thing that can help out our fellow members is accuracy and reliability, especially on threads that do not generate as much traffic as they once did. As to the what the typo-ed inference is called, I don't have the slightest idea. Never seen it before. However, human ingenuity knows no bounds, so I will venture to conjure one up. Replacement rule... I dub thee "ignoring the obvious," or Obviare Veritas. Only by ignoring the obvious can we infer opposite truth values at our beckon whim within a closed system.

---------- Post added 11-10-2009 at 03:33 PM ----------

kennethamy;102768 wrote:
"An illegitimate step"? Why should it have a name?

I think the word you are looking for is "conversion".

Because people use it. Just as when we give names to other invalid inferences also known as formal fallacies.

And yes, that's the name. Do you know a resource on these kind of inferences and their names?

kennethamy

Tue 10 Nov, 2009 08:46 am
@Emil,
Emil;102777 wrote:
this resource for symbols.

---------- Post added 11-10-2009 at 03:31 PM ----------

---------- Post added 11-10-2009 at 03:33 PM ----------

Because people use it. Just as when we give names to other invalid inferences also known as formal fallacies.

And yes, that's the name. Do you know a resource on these kind of inferences and their names?

Logic - Inverse

So, I guess it does have a name.

VideCorSpoon

Tue 10 Nov, 2009 09:20 am
@Emil,
Emil;102777 wrote:

You are forgetting the very nature of Obviare Veritas. When we infer Obviare Veritas, this reply is actually a delicious recipe for french onion soup. LOL! P.S. I hope you understand that all of this is said in jest?

Michel

Tue 10 Nov, 2009 11:29 am
@Emil,
Emil;102777 wrote:
Is "inverse" a synonym for "converse" or is there some difference?

Let's take this: P→Q. The converse of it is Q→P and the inverse is ~P→~Q. The inverse and converse, while logically equivalent, are not synonyms.

Quote:

It's not a move; it's the inverse.

Emil

Tue 10 Nov, 2009 03:31 pm
@Michel,
Michel;102823 wrote:
Let's take this: P→Q. The converse of it is Q→P and the inverse is ~P→~Q. The inverse and converse, while logically equivalent, are not synonyms.

Yes, I learned that from the previous link of yours.