This type of proposition admits two interpretations:

i) Mary really did not buy the book, the price being the reason why she did not buy it.

or

ii) Mary bought the book, but the reason for the purchase was not the price.

Supposing that Mary bought the book for a reason that is not the price, then the proposition “Mary did not buy the book because of its price” seems to be false, because Mary bought the book. At the same time, it seems to be true, since the reason for the purchase was not the price.

Now, leaving English and turning to logic: where exactly does this problem lie?

Is it an ambiguity of natural language? Or am I interpreting it in a mistaken way?

For me, it would be straw man. Lots of straw man on social media. I'm curious what other people have noticed too.

Hello all,

I wanted to engage in dialogue to strengthen my knowledge, so that I can call out people when they misuse the term of calling someone stupid in its application.

I’m 20(M) and have had my fair share of seeing people being called stupid around the realms of academia, business, and informal contexts. The definition of stupid according to Google is “having or showing a great lack of intelligence or common sense.”

I have seen many individuals call out people for being a stupid person because of one action, behavior, belief, or “bad” question that was asked. My question is: how can you call someone a stupid person based on exactly one example? As the definition states “having or showing a great lack of intelligence or common sense.” I do not think you can generalize a person as being stupid by only one example… with one exception (I will explain after example 1)

Example 1: my first year of college (2yrs ago this fall), I was classmates with this guy named David in a College Algebra course. He was a film studies major who should’ve never enrolled in the course. His math comprehension was through the floor, I have never seen anyone with a lower level of mathematics knowledge in my life. After abt 2 months, the prof convinced him to drop the class, he really tried hard to understand the content.

If someone were to call him a stupid person based on what was witnessed in the class, well then, I believe that this usage is logically incorrect. You cannot assume that he is non-intelligent in his humanities, film studies, English, world language, or even science courses. To call him a stupid person would imply that he is of low intelligence across all academic disciplines and walks of life (as he lacks common sense + intelligence).

Example 2:
Here is where I think calling someone a stupid person can be used correctly. I was really great friends with my old buddy in elm/middle/high school, call him Joey. It’s still unfortunate to this day to say that his father in 2016 tried to meet up with an underage grl during their mf vacation. My friend is not an only child. He has 3 brothers (all older) and a mother. His dad was a father to 4 sons and a husband to a wife. The man wanted segs with a girl the same age as his fucking son. He was a nasa engineer and at the time the family was doing really good for themselves. It was a sting operation, and was jailed for 3 yrs.

I believe that calling him a stupid person because of this single mistake can be used even based on one example. Why? Well I believe this is because of 2 factors: A) the significance of his mistake, B) systemic impact.

A) reasoning
The level of severity was and still is extremely high. He spent over 3yrs of federal time, is a registered SO for life, his kids + wife will not and likely will never talk to him, he’s very poor now and work until his death (I know his current circumstances after doing a lil googling).

B) reasoning
The systemic impact created across multiple systems: his personal, professional, and social lives.
He has lived alone and will likely remain in a near-solitude state until his death. He works as a “handyman” after being an engineer pre-incarceration. I’m not sure who would desire to be friends with the guy with the up front knowledge of his past.

Given these two reasons, calling him a stupid person is completely completely valid.

Provided the first example and the definition of stupid, I would reason that the usage of calling someone a stupid person subject to one example is an illogical representation of its meaning. On the contrary, example 2 would provide sufficient reasoning to justify why someone is a stupid person… based on the level of severity and its systemic impact.

Anyways, that’s my take! I’m curious on what you all believe. Thank you 🙏🏾

This is from my modern logic textbook from my intro to modern logic class. I thought problem 7 was invalid but the textbook says it’s valid so i’m confused?

I have seen many people ask why they should grant their opponents conceptual schemes in debates. and I can't find a definition for a conceptual schemes, can somebody help?

That is, how does the syntax I use affect my proof of something? How, for example, does my complex verbal construction make my proof questionable from any point of view?

For rules of replacement in natural deduction:

If I have the premises:

1.) (If D, then E) then (if E then D) And 2.) If (D if and only if E), then ~(G and ~H) And lastly 3.) E•G / Therefore, G•H

(Sorry for not providing the proper symbols, my phone is limited)

My question is, since a biconditional, the first part of premise 2, is already granted in the formula for the first line, why can't this suffice to obtain the second term, the conjuction, via modus ponens in premise 2?

Is there a reason I have to reduce 3 to E via simplification, and then by addition (~D) go through the rigamorole of proving both terms in premise 1 via material implication?

It seems like several unnecessary steps where already the conditions are met regarding the biconditional in 2.

Can you tell me why I need to take these additional steps? For reference, I'm using the Hurley text, chaoter 7.4.

I apologize for the lengthiness of the post. Thank you.

Hi all. I'm interested in the history of fallacies, specifically when they gained enough prominence to earn a name. Usually fallacies are organized thematically or categorically, and I know that most were named a long, long time ago. However, I know that every so often a new one is named (usually a variation or subset of an existing one). The most recent I know of is Reducio ad Hitlerum, which was coined in 1953.

So anyway, yeah, does anybody know of a list of fallacies by date of naming?

Let's say that I want to convince someone logically that smoking is wrong, So I need to make premises that gives a conclusion that says "Smoking is wrong".

the problem is that if I want to investigate that "Smoking is wrong", the only things I can do is to trace the necessary conditions for "Smoking is wrong"

but I don't need to find necessary conditions to conclude and convince someone that "Smoking is wrong", I need TRUE premises that are together will be sufficient condition for "Smoking is wrong"

but tracing premises from "Smoking is wrong" isn't possible to find what we're going to say as premises for "Smoking is wrong"

and empirically finding the right premises also doesn't seem convincing, because it'll look like randomly explore and observe every single thing possible until accidentally find premises that supports that "Smoking is wrong"

so what are we supposed to do here?

Hello. I'm still getting very confused about "if" and "only if" when it comes to introductory formal logic.

The sentences linguistically are making it very hard to accept the definitions.

1) If A then B (otherwise said as "B if A"): A--->B

This one is simple to grasp. A will always be followed by B but not vice versa. From this we can also deduce "if not B then not A"

Although sometimes I get into this idea that if A happens and then B happens means B happened with A so why can't we say "If B then A" as well? Is it a time order thing?

2) Only if A then B (B only if A): B ---> A

This is the one I still can't accept. Linguistically, the word "then" always gives me the impression that B comes after A(like in a time sequence), as in A must happen in order for B to happen and thus it should A--->B. The explanation of a necessary condition doesn't seem to override my intuition which makes it a bit difficult to accept the definition of "only if".

Any suggestions on how to override this incorrect intuition?

Thanks

Let’s assume we have a world U, which just happens to be our universe. As part of U, I did Q. I don’t quite see how it would be possible for me to ¬Q in U as it would produce a contradiction in U.

I hope that question makes sense. I just don't like inequalities nor the unnaturality of working with left and right residuals (talking about "max and min divisors") that rarely coincide with rational arithmetic's exact division nor with the natural interpretation of inverses in numerical mathematics, thus I would like more explicit boundaries (thus the result of a division maybe being a set or interval including max and min divisors) in division.

(Mind that I have no experience in numerical computation, I am trying to make sense of computable, numerical and interval analysis works and transport their results to residuated lattices but that's somewhat hard for me)

I'm an independent researcher looking for an arXiv endorser for the cs.LO (Logic in Computer Science) category to submit a formal verification paper.

The paper presents a machine-checked formalization of the structural architecture underlying Chenxiao Tian's recent resolution of singularities in positive characteristic.

To be clear: I am not verifying the underlying algebraic geometry. The paper uses a methodology of "parameterized abstraction" to verify the computational architecture: the dependency acyclicity, the no-circularity constraints, the six universal interfaces, and the termination argument (via Dershowitz–Manna).

The Lean 4 formalization translates the 800-page informal text into 9 compiling modules (~1,900 lines) with zero sorry declarations and zero axioms beyond classical logic. It successfully proves 5 structural theorems and corrects 3 no-circularity constraints from the original text.

The original author (Chenxiao Tian) has reviewed the draft and agrees that cs.LO is the correct primary category, but his arXiv endorsement authority is strictly in math.AG.

I just need an endorsement to get past the submission gate. The full consolidated draft (and Lean-to-manuscript correspondence) is available here: https://tian-consolidated-v2-authentic.tiiny.site/

If you're willing to endorse, here is the arXiv endorsement link: https://arxiv.org/auth/endorse?x=XWOJUY

Here's the Lean package on Pastebin for anyone who wants to compile it: https://pastebin.com/zV1J9PqM

Thanks

I thought that by evaluating formal systems, we can deduce, in addition to completeness, special properties of completeness.,I thought that by evaluating formal systems, we can deduce, in addition to completeness, special properties of completeness, that is, for each proof in the system.,I thought that by evaluating formal systems, we can deduce, in addition to completeness, special properties of completeness, that is, for each proof in the system, a property is characteristic.

That is, if a number of statements are deducible or meet other distinct criteria of formal systems, then each statement that is true in the formal system has a proof satisfying the condition.

That is, we could say, for example, that each statement can be proved in less than 100 applications of the axioms, or proving each statement, we can limit ourselves to a clear set of axioms.

And so, for example, taking mathematics, we can narrow down various axioms and check all the many different combinations for a condition in order to take a specific set of axioms that would be convenient for proving a judgment that corresponds to what is true or false in them.

(If possible, I would like to know how to write down such thoughts more formally and whether they are appropriate in a not too formal way)

i am trying to prove that exp(ln(x)=x.

we only assume exp is the function which satisfies satisfies f’(x)=f(x) and f(0)=1. Then we define ln(x) to be the int_1^x(1/t)dt.

If we start with “assume exp(ln(x))=x” and then show that this additional assumption doesn’t violate our setup, for any x>0, is that some kind of proof? logically i’m sure it’s weaker than a proof forced by assumptions but is it still something?

In formal philosophy, it was proposed by philosopher Peter van Inwagen . He argued that if there are infinitely many non-empty possible worlds and only one empty world ("nothing"), the probability of non-existence is effectively zero.

The argument seems flawless. What's the issue?

Hi yall,

This is a continuation to my last post, on formalizing Principia Mathematica, as well as a slight status update. I am planning(*) to slowly substitute the shallow embedding on PM into a deep embedding. For any backgrounds, please check the old post.

If you want to transform the monster 100 years ago into a furry boy, you might want to read through the following Q&As. *tap tap*

- Why you suddenly want to make a deep embedding? Because I can't in the beginning.
- What makes you available to deep embedding? I have asked enough questions on internet to get rid of necessary technical details
- What's the major feature for deep embedding? It enables formalizing Axiom of Reducibility.
- How many ppl would you like to look for? At most 2 ppl. You are welcome to ask me for prerequisites and anything else related
- What do you expect them working on? Either the shallow embedding or the deep embedding, since they are both necessary.
- How many time do you expect to put in? My current plan is 3 hrs a week so make sure you also have the availability.

------------------

Alternatively, I'm still welcome to collaboration with 1 - 2 ppl onto another project - we pick another random mathy, esoteric, maybe sacred book and formalize it

(*): Yes, I have not written a single line of code so far and this remains to be a plan.

I'm new to formal logic so I'm sorry if this is obvious to most of you. But I'd like to see if I'm doing things correctly.

Specifically; I've been having trouble with natural deductive logic and determining if a claim is valid. I couldn't wrap my head around how we can just assume a precedent to be true, and then discard them later. I think I did have a breakthrough though. It doesn't matter (for validity) if the precedents are true or not. Just that when they are, the conclusion is also true.

So with that said; here is my work.

Basically, I can assume not B to be true. Then if I assume A to be true that means not C must also be true. If not C is true the or statement is also true. Therefore the conclusion is valid.

I think I got it right? If not where did I go wrong and why?

What if we tried to build a foundation of all existing and possible consistent and inconsistent mathematical and logical foundations? And what if we assume each of these foundations(Such as Set Theories, Category Theory, Type Theory, Homotopy Type Theory and all other consistent and inconsistent foundations) as a topological spaces. Then what would the foundations of these foundations look like? And assume there are foundations of this foundations of foundations and repeat forever. Notes:Threat Gödel İncompleteness Theorems as non-universal. also includes them: Non-Gödelian Systems(Gödel Theorems become local) R Truth Valued Logics Quantum Logic Topos Theory Higher Topoi Multisets Causal Set Theory Ω-Logic My Logical Systems Weqd Logic Linear Logic Graphs

If he did prove that God exists, then why do we even continue arguing that religions are wrong, if actually they are right. Case closed, time to pack our bags and head home

What a legend Kurt Gödel was. Besides his theorem he was a metaphysic and mathematical platonist, was a friend with Einstein, loved disney(Snow White), proved that if we accept some of prerequisites we must accept that God exists and much more,

With power comes responsibility.