Paul P. Mealing

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Tuesday, 30 April 2024

Logic rules

I’ve written on this topic before, but a question on Quora made me revisit it.
 
Self-referencing can lead to contradiction or to illumination. It was a recurring theme in Douglas Hofstadter’s Godel Escher Bach, and it’s key to Godel’s famous Incompleteness Theorem, which has far-reaching ramifications for mathematics if not epistemology generally. We can never know everything there is to know, which effectively means there will always be known unknowns and unknown unknowns, with possibly infinitely more of the latter than the former.
 
I recently came across a question on Quora: Will a philosopher typically say that their belief that the phenomenal world "abides by all the laws of logic" is an entailment of those laws being tautologies? Or would they rather consider that belief to be an assumption made outside of logic?

If you’re like me, you might struggle with even understanding this question. But it seems to me to be a question about self-referencing. In other words, my understanding is that it’s postulating, albeit as a question, that a belief in logic requires logic. The alternative being ‘the belief is an assumption made outside of logic’. It’s made more confusing by suggesting that the belief is a tautology because it’s self-referencing.
 
I avoided all that, by claiming that logic is fundamental even to the extent that it transcends the Universe, so not a ‘belief’ as such. And you will say that even making that statement is a belief. My response is that logic exists independently of us or any belief system. Basically, I’m arguing that logic is fundamental in that its rules govern the so-called laws of the Universe, which are independent of our cognisance of them. Therefore, independent of whether we believe in them or not.
 
I’ve said on previous occasions that logic should be a verb, because it’s something we do, and not just humans, but other creatures, and even machines. But that can’t be completely true if it really does transcend the Universe. My main argument is hypothetical in that, if there is a hypothetical God, then said God also has to obey the rules of logic. God can’t tell us the last digit of pi (it doesn’t exist) and he can’t make a prime number non-prime or vice versa, because they are determined by pure logic, not divine fiat.
 
And now, of course, I’ve introduced mathematics into the equation (pun intended) because mathematics and logic are inseparable, as probably best demonstrated by Godel’s famous theorem. It was Euclid (circa 300BC) who introduced the concept of proof into mathematics, and a lynch pin of many mathematical proofs is the fundamental principle of logic that you can’t have a contradiction, including Euclid’s own relatively simple proof that there are an infinity of primes. Back to Godel (or forward 2,300 years, to be more accurate), and he effectively proved that there is a distinction between 'proof' and 'truth' in mathematics, in as much as there will always be mathematical truths that can’t be proven true within a given axiom based, consistent, mathematical system. In practical terms, you need to keep extending the ‘system’ to formulate more truths into proofs.
 
It's not a surprise that the ‘laws of the Universe’ that I alluded to above, seem to obey mathematical ‘rules', and in fact, it’s only because of our prodigious abilities to mine the mathematical landscape that we understand the Universe (at every observable scale) to the extent that we do, including scales that were unimaginable even a century ago.
 
I’ve spoken before about Penrose’s 3 Worlds: Physical, Mental and Platonic; which represent the Universe, consciousness and mathematics respectively. What links them all is logic. The Universe is riddled with paradoxes, yet even paradoxes obey logic, and the deeper we look into the Universe’s secrets the more advanced mathematics we need, just to describe it, let alone understand it. And logic is the means by which humans access mathematics, which closes the loop.
 


 Addendum:
I'd forgotten that I wrote a similar post almost 5 years ago, where, unsurprisingly, I came to much the same conclusion. However, there's no reference to God, and I provide a specific example.

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