4
votes
1answer
74 views

In Whitehead and Russell's PM, are overlapping ranges of significance necessarily identical?

In Principia Mathematica summary of ✳63 In virtue of ✳20.8, we have $\vdash : \phi a ∨ \sim\phi a . ⊃ . \hat{x}(\phi x \vee \sim \phi x ) =t‘a$ i.e. if "$\phi a$" is significant, then ...
3
votes
5answers
296 views

Can mathematics be traced back to a fundamental system of truths?

I'm not sure exactly how to state this question, or even if it belongs here. Still, I hope you will consider it, as I find it very interesting: Most of the results I've seen in mathematics come from ...
1
vote
3answers
117 views

When and where the concept of valid logic formula was defined?

I was stimulated by a recent question about Gödel Completeness Theorem. All my citations are from Jean van Heijenoort (editor) From Frege to Gödel A Source Book in Mathematical Logic (1967). Gödel's ...
2
votes
1answer
91 views

Why can't ✳1.1 be expressed symbollically in Whitehead and Russell's PM?

✳1.1. Anything implied by a true elementary proposition is true. Pp. In the follow passage, it says, "we cannot express the principle symbolically, partly because any symbolism in which p is ...
4
votes
4answers
196 views

What is the difference between asserting “$\phi(a)$” and asserting “$\phi(a)$ is true” in Whitehead and Russell's PM?

The first edition of Principia Mathematica clearly distinguishes "Socrates is a man" and "'Socrates is a man' is true." Judging from the context, the distinction is neither a primitive idea nor a ...
9
votes
1answer
106 views

What was the planned topic of Gödel's second paper on incompleteness?

Gödel's incompleteness theorems first appeared together in a paper titled (translated to English) "On formally undecidable propositions of Principia Mathematica and related systems I," with the Roman ...
9
votes
5answers
441 views

What are reasons why some symbols in mathematical logic are not standardized?

Why is so hard to find a standardisation regarding symbolism and/or terminology in Mathematical Logic ? We see again and again students asking if e.g. $\rightarrow$ and $\implies$ means the same ...
2
votes
1answer
82 views

Who first proved that the second-order theory of real numbers is categorical?

The second-order theory of real numbers is obtained by taking the axioms of ordered fields and adding a (Dedekind) completeness axiom, which states that every set which has an upper bound has a least ...
5
votes
1answer
66 views

What is $M_x$ in Frege's Basic Law IIb?

Gottlob Frege's magnum opus, "The Basic Laws of Arithmetic" (Die Grundgesetze der Arithmetic in German) constitutes one of most impressive and meticulous attempts at developing a rigorous foundation ...
9
votes
5answers
291 views

Purpose of the Peano Axioms

Wikipedia says the Peano Axioms are a set of axioms for the natural numbers. Is the purpose of the axioms to create a base on which we can build the rest of mathematicas formally? If this is true ...
8
votes
4answers
500 views

Can we prove that odd and even numbers alternate without using induction?

It is a simple exercise to prove using mathematical induction that if a natural number n > 1 is not divisible by 2, then n can be written as m + m + 1 for some natural number m. (Depending on your ...
9
votes
2answers
418 views

Where, specifically, did Principia Mathematica fail?

I'm very fascinated by the book Principia Mathematica. From what I've learned so far, Principia Mathematica set out to be, essentially, the bible of mathematics and logic, from which all mathematical ...
7
votes
1answer
136 views

Mathematics Essence

I started reading History of Philosophy and readily noticed that the origins of our actual natural sciences were due to the proper use of inductive logic.Our Physics/Chemistry and Biology all are ...
4
votes
1answer
102 views

The manuscript Summa Logicae (William of Ockham)

The Summa Logicae (Latin, in English it's the Sum of Logic) is a textbook on logic by William of Ockham. There are articles about the Summa Logicae in Wikipedia and in Logicmuseum. It was published ...
10
votes
1answer
331 views

Any branch of math can be expressed within set theory, is the reverse true?

Set theory seems to have the property of being "universal", in the sense that any branch of math can be expressed on its language. Is there any other branch of math with this property? I am asking ...
5
votes
4answers
525 views

Disjunction: Why did the inclusive “OR” become the convention?

In How to Prove it by Velleman, for defining disjunctions, he gives the difference between exclusive "OR", and inclusive "OR." Given two events $P$ and $Q$, the disjunction is defined for them as: ...
12
votes
0answers
132 views

Is Dover publishing Moore's book on the Axiom of Choice? [closed]

Dover is publishing a paperback edition of Gregory H. Moore's Zermelo's Axiom of Choice: Its Origins, Development, and Influence. It's supposed to come out March 20th and is available for pre-order at ...
16
votes
4answers
730 views

How did the ancients view *infinitesimals*?

With some category/topos theory we can now put infinitesimals on a rigorous ground, as in Bell's A Primer of Infinitesimal Analysis, where the author introduces $\epsilon$ satisfying \begin{equation} ...
2
votes
5answers
214 views

Is there an axiom that prevents other axioms from contradicting each other?

i.e. Does an axiom already exist, which prevents the addition of those new axioms which can contradict already existing axioms? Also, who decides that something is an axiom?
4
votes
2answers
210 views

why does soundness seem to be less important than consistency for the structuralist?

If I am not wrong, many mathematicians (I believe this is not only restricted to structuralists) agree that an inconsistent formal system does not have any model. By model I mean some kind of set ...
14
votes
1answer
338 views

Mendelson's $\mathit{Mathematical\ Logic}$ and the missing Appendix on the consistency of PA

In the first edition of Elliott Mendelson's classic Introduction to Mathematical Logic (1964) there is an appendix, giving a version of Schütte's (1951) variation on Gentzen's proof of the consistency ...
1
vote
2answers
131 views

Semantic parsing of a sentence from “The mathematical analysis of logic” By Goerge Boole, 1847

Having the pleasure of reading some original text, I was wondering if someone can translate two small statements on the second half of page 11 from ...
9
votes
1answer
160 views

Who first explicitly noted that second-order logic is unaxiomatizable?

As every student now knows, second-order logical consequence is unaxiomatizable. (At least when we read the second-order quantifiers in the natural way, as running over all possible properties on the ...
2
votes
1answer
134 views

Earliest proof of completeness for axiomatization of Boolean Algebra

Suppose we define Boolean algebra as the system of algebraic rules (logical equivalences) obeyed by AND, OR, NOT with AND, OR, NOT defined by the usual truth tables. We also have variables, which can ...
4
votes
1answer
200 views

Motivation behind Theory of Relations?

I looked through the nice paper by Tarski On the Calculus of Relations. In the beginning he touched a motivation behind Theory of Relations but this part was not clear to me (page 1, very beginning): ...
2
votes
1answer
189 views

Origin of the Notion of a Well-Formed Formula

When was the idea of a well-formed formula first stated or can get inferred as such under another name?
12
votes
1answer
461 views

successful absurd formalities

Has anyone published in print or on a web site or elsewhere a compilation of successful illogical formal arguments? By those I mean arguments that follow a form in disregard of the legality of its ...
2
votes
2answers
130 views

Were PR functions considered to be the class of total recursive functions?

At some point of history, were the class of primitive recursive functions considered (or even conjectured) to be the class of total recursive functions? I think I faced this claim sometime ago, but ...
3
votes
3answers
458 views

Sheffer stroke the most important advance in logic?

I think I once read, or heard, that Bertrand Russell once said that the discovery that all logical operators are expressible in terms of the Sheffer stroke was the most significant advance in logic ...
10
votes
1answer
313 views

Is Hilbert's second problem about the real numbers or the natural numbers?

In his famous "23 problems" speech, Hilbert gave his second problem as follows: The axioms of arithmetic are essentially nothing else than the known rules of calculation, with the addition of the ...
1
vote
2answers
276 views

What is the origin of the prefix logic notation used in WFF 'N PROOF?

The classic "modern logic" game of WFF 'N PROOF uses a set of symbols to represent logical relations that I've seen used nowhere else: $C$ for then; $A$ for or; $K$ for and; $E$ for if and only if; ...
22
votes
4answers
1k views

Who invented $\vee$ and $\wedge$, $\forall$ and $\exists$?

I can rather easily imagine that some mathematician/logician had the idea to symbolize "it E xists" by $\exists$ - a reversed E - and after that some other (imitative) mathematician/logician had the ...
19
votes
4answers
2k views

Where did mathematicians learn how to do truth tables?

I'm trying to find out who invented truth-tables. Here is what I have so far. Leibniz 'invented' binary arithmetic, or at least is the first one recognized to have codified and explained a base 2 ...
64
votes
15answers
6k views

Why did mathematicians take Russell's paradox seriously?

Though I've understood the logic behind's Russell's paradox for long enough, I have to admit I've never really understood why mathematicians and mathematical historians thought it so important. Most ...