Category Archives: Logic

The Principle of Charity (Revisited)

As an adjunct faculty member of Philosophy, one of my soapbox lectures to my students is the importance and application of the Principle of Charity. I mention it in the 1st Day Syllabus, I mention it again about half-way through the semester, and I include it as a short-answer question on the Final Exam.

At its core, the Principle of Charity (PoC) involves thinking well of people; their intentions, their capabilities, and their knowledge level. I take it very seriously because (1) it is the civil, respectful, and necessary thing to do and (2) it actually makes discussions or discourse more efficient by not wasting time on misunderstandings or by committing straw person fallacies. In either case, the PoC has a wide range of important uses and that is why I hammer it into to my students from the get-go. Below, I will explain what it is and give some pertinent examples as well as provide some good resources for further reading.

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Concept-Checking: Authority Figures (AFs) vs. Subject Matter Experts (SMEs)

On the surface, one may think that an ‘authority’ or ‘authority figure’ is the same thing (or nearly the same thing) as an ‘expert.’ Teasing out the key differences to these concepts and their functions is of considerable philosophical significance.

Let’s take an ‘authority figure’ first. Someone who is an authority figure is someone who is seemingly responsible, either preventatively or reactively, for enforcing observance or obedience to a particular norm/rule/principle/ideal. They either encourage us to uphold (or at least not to break) that norm/rule/principle/ideal. Or, if we decide not to do what is asked or expected of us, they may punish us for our seemingly incorrect choice.

We can think of 3 key examples within our daily lives: the religious leader (e.g. priest, rabbi, imam, guru, etc.), the police officer (or military official), and the calculator (or the computer program).

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Concept-Checking: Nonrational vs. Irrational vs. Rational

Though this is a relatively rare distinction to be made, it is nonetheless an important one. Nonrationality is NOT the same thing as irrationality. These two terms are different and must be recognized as such. While we are at it, we should discuss what ‘rationality’ actually is…

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An Initial Look into ‘Graham’s Hierarchy of Disagreement’

  1. Name Calling
  2. Ad Hominem
  3. Responding to Tone
  4. Contradiction
  5. Counterargument
  6. Refutation
  7. Refuting the Central Point
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Summary: Einstein vs. Logical Positivism by Rossen Vassilev Jr.

The original article can be found at:

Vassilev begins his article by pointing out that Logical Positivism was a philosophical movement that originated in the 1920s. Arguably its most critical mission was to establish the same methodology of science and mathematics for other fields, particularly philosophy. The logical positivists dismissed any and all ‘non-scientific’ speculation from genuine analysis or explanation. They insisted that such statements were literally meaningless; only statements that could be logically verified or corroborated through experiment/observation have meaning. This was known as the Principle of Verification (or Verification Principle) and was the driving philosophical and epistemological force behind the Vienna Circle (a particularly influential group of logical positivists).

According to the Principle of Verification, the meaning of any statement lies in its method of verification. Moreover, statements about, say, God or art or ethics would all suddenly be technically meaningless according to the logical positivists. Logical positivists were excited at this prospect because they were very much committed Naturalists. But not all philosophers were on-board with their philosophical approach or its underlying intentions.

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Sentential Logic: Rules of Inference for Deriving Proofs


Ampersand-In (&I): If one has available lines, A and B, then one is entitled to write down their conjunction, in one order A&B, or the other order B&A.

Ampersand-Out (&O): If one has available a line of the form A&B, then one is entitled to write down either conjunct A or conjunct B.

Wedge-In (∨I): If one has available a line A, then one is entitled to write down the disjunction of A with any formula B, in one order AvB, or the other order BvA.

Wedge-Out (∨O): If one has available a line of the form A∨B, and if one additionally has available a line which is the negation of the first disjunct, ~A, then one is entitled to write down the second disjunct, B. Likewise, if one has available a line of the form A∨B, and if one additionally has available a line which is the negation of the second disjunct, ~B, then one is entitled to write down the first disjunct, A.

Double-Arrow-In (↔I): If one has available a line that is a conditional A→B, and one additionally has available a line that is the converse B→A, then one is entitled to write down either the biconditional A↔B or the biconditional B↔A.

Double-Arrow-Out (↔O): If one has available a line of the form A↔B, then one is entitled to write down both the conditional A→B and its converse B→A.

Arrow-Out (→O): If one has available a line of the form A→B, and if one additionally has available a line which is the antecedent A, then one is entitled to write down the consequent B. Likewise, if one has available a line of the form A→B, and if one additionally has available a line which is the negation of the consequent, ~B, then one is entitled to write down the negation of the antecedent, ~A.

Double Negation (DN): If one has available a line A, then one is entitled to write down the double-negation ~~A. Similarly, if one has available a line of the form ~~A, then one is entitled to write down the formula A.

Sentential Logic Practice: Assessing a Proof of King’s Argument about the Purpose of Life

Recall that King set up his argument as follows:

Premise 1: Either our life’s purpose is achievable or it is not.
Premise 2: If it is achievable then after it is achieved we no longer have a purpose.
Premise 3: Then our lives would be futile.
Premise 4: If it is not achievable then attempting it would end in failure, and to continue would be futile.
Conclusion: Therefore, either way, our lives are ultimately futile.

Let’s begin by defining our library of symbolic terms:

A = Humanity’s life purpose is achievable at some point before death
N = A human’s life purpose ceases to exist if it is achieved
F = Human’s life purpose is futile if it ceases to exist
U = Attempting to achieve humanity’s life purpose will end in failure

This argument is definitely a valid one because we can assemble and test a sample derivation:

So if we provisionally assume A (‘Our purpose is achievable’), then we can eventually achieve it. Once we do, since our life purpose is like a desire that is eliminated (or ceases to exist) once it is satisfied, we no longer have a life purpose (N). And if we no longer have a life purpose, then our lives would be (or become) futile (F).

Now, if we provisionally assume ~A (‘Our purpose is NOT achievable’), then we will never be able to achieve it. It will always elude our grasp or its own completion. If our purpose is not achievable, then attempting to achieve that purpose would end in failure and our lives would be (or become) futile (U & F).

Regardless of whether our life purpose is achievable or not, King reasons, our lives would be (or become) futile, inevitably. That would hold true for everyone at all times and in all places.

The problem is that we have no reason to believe that a purpose is a one-and-done type of deal. It could be that life’s purpose is similar to being virtuous (i.e. it is an ongoing process rather than a completed product). Even if our life’s purpose were fulfilled, there are still various hypothetical situations and contexts in which one could reasonably expect to either have to (1) maintain the completion or fulfillment of their life’s purpose or (2) complete or fulfill a new or modified purpose for their own life.

There is no logical contradiction in this alternate definition of purpose. King’s article definitely gives us much to reflect upon, but ultimately his analysis relies on a faulty definition (or understanding) of purpose; an alternative definition provided can sidestep this problem though, thereby undermining the soundness of his argument’s conclusion.

Commentary: Looking for the Purpose of Life by Brian King

*The original article can be found at:

Brian King writes a solid introductory piece about what the purpose of life may be and why it is such a thorny question for philosophers to answer.

*Video below unrelated, but still entertaining and quasi-relevant!*

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Concept-Checking and Assumption-Checking

Just as there are numerous websites, agencies, and sources that ‘fact-check’ the various statements made by politicians, public figures, and the like, I want to use part of my platform here to ‘concept-check’ and ‘assumption-check’ different statements made by whomever (historians, philosophers, journalists, etc.).

Concept-checking will involve ensuring that all of the technical concepts are being accurately and, at least initially, fairly portrayed in articles or books or magazines I read. So, for instance, if someone claims that Nietzsche’s ‘eternal recurrence’ is about how badly he wishes he could experience the joy of riding his bicycle for the first time extended over an infinity, then I would assert that they are incorrect and need to be concept-checked (along with the relevant authoritative evidence and argumentation).

Assumption-checking will involve pointing out some common sense and likely events or situations in all (or at least most) of our lives differ from the assumption being offered. So, for instance, if someone talks about how free each individual in the United States is, I would point out how that assumption doesn’t ring as true as they would like. For instance, consider the divergence in experiences among POC and white America. There are VAST differences that cannot and should not be glossed over, especially when engaging in philosophical analysis and truth-seeking. That same principle applies here.

Moving forward, I will specifically mark the CC and AC posts and provide all the proper documentation that I can. If you think of any or come across any articles you think would be interesting, please send them my way!

Sentential Logic Practice: Symbolizing More Natural Sentences

1.) Natural sentence: Either I will eat ham or I will eat turkey.
Library: H = I will eat ham, T = I will eat turkey
Symbolization: H v T

2.) Natural sentence: Yesterday, we danced, played, and ate so much!
Library:  D = we danced so much, P = we played so much, A = we ate so much
Symbolization: [D & (P&A)]

3.) Natural sentence: Harrison or John will win Prom King
Library: H = Harrison will win Prom King, J = John will win Prom King
Symbolization: H v J

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