180 - Proof Positive: The Logical Tradition | History of Philosophy without any gaps

Posted on 15 June 2014

Logicians ply their trade across a millennium of Islamic history, considering such issues as the status of logic itself and the Liar Paradox.

Themes:

Logic

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Apple Podcasts App

I listened to this episode with my iPhone’s web browser, but I don’t seem to be able to get it to show up on my Podcasts app. Maybe there’s just a delay.

upload

Sorry, this was my fault - I didn't upload it properly. But as you say it's fixed now!

Thanks for the for the

Thanks for the for the response. Glad it was simple.

Logic Resource

David Marans,Open Access, LOGIC GALLERY, http://humbox.ac.uk/3682/

Mulla Nasr al-Din

Is this character based on an actual person, or is it just a placeholder name people use for such jokes?

Nasr al-Din

Good question. I don't know actually but I assumed the latter.

We still study logic in Madrasa!

As late as the 20th century? Bihari's Sulum Al-Ulum and dozens of commentaries on it are still required reading in many of the better off subcontinental madrasas. In some cases commentaries on the Sulum account for the bulk of the subject, alongside Al-Abhari's classic commentary on Ibn Al-Muqaffa's translation of the Isagoge. It might be rare, but a distant relative of mine did study Avicenna's Al-Shifa during her time in madrasa which is very unusual. The extent to which new works on logic are produced appears miniscule, for various reasons, but I think it's wrong to imply that it's a dead tradition. Avicenna, Mullah Sadra, Muhibb Allah Bihari, Hussein Maibazi, Mullah Jaunpuri and Mir Muhammad Zahid are still studied in many places and not as mere historical figures.

Madrasa curriculum

Yes, thanks for pointing this out! I think I allude to this a bit more in later episodes; and anyway I didn't mean to imply it is a dead tradition, it also lives on in the schools of Iran. I'm fascinated to hear about your relative studying Avicenna directly!

Liar's Paradox

I first encountered the Liar's Paradox in "Sideways Arthimatic from Wayside School." There it is "1. the answer to question 2 is false" "2. the answer to question 1 is true". the 'solution' i came up with in elementary school was focused on breaking the infinite chain. so i said if 1 is true, 2 is false, but if 2 is false, then 1 can't be true, so 1 is false. however, just because 1 is false, doesn't mean 2 is true, it just means that 2 is a different kind of false than 1 is refering to. therefore both of them are false. i guess it was based on the idea that there is only one way to be right but many to be wrong. i don't really fully remember the reasoning, but the answer stuck with me all these years.

if i wanted to follow young me's ideas and explore them, being my own historian, i might argue:

"if 1 is true, then 2 must be false. but then if 2 is false, one just has to be not true. If 1 is not true, that doesn't mean it is false (just like not white doesn't mean black), therefore, 2 is false, and 1 is just not true. therefore, the problem is the idea that a statement is only true or false."

i don't think i'm hitting on any real solution, just thought i'd share, however.

Liar's paradox

Yes, that is a possible solution: just introduce a third status or truth value like neither true nor false. But most logicians, historically, were committed to the Aristotelian principle that there is no such third truth value so this was not an available way out.