Category: Logica Docens
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The Truth Operator and the Truth Predicate
This is an addendum to our earlier discussion which I hope will advance it a step or two. We heard Alan Rhoda claim that the following sentence is false: 'If nothing exists, then it is true that nothing exists.' Let's think further about this. We first note that 'If nothing exists, then it is true that nothing…
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A Counterexample to P –> It is True that P?
Alan Rhoda e-mails: In a recent post you write: The objector is inviting us to consider the possible situation in which beings like us do not exist and no truths either. The claim that this situation is possible, however, is equivalent to the claim that it is true that this situation is possible. I think there's a…
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More on the Law of Non-Contradiction and its Putative Empirical Refutability
A reader's e-mail with my comments in blue: Nice post on the LNC. That topic is a real quagmire, isn't it? I’ve lost the link to the Science Daily report of the Cleland experiment, so the details of how he confirmed the superposition are lost to me, but I’m really struck by the fact that you…
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An Empirical Refutation of the Law of Non-Contradiction?
Nice work if you can get it! Here we read: A team of scientists has succeeded in putting an object large enough to be visible to the naked eye into a mixed quantum state of moving and not moving. Andrew Cleland at the University of California, Santa Barbara, and his team cooled a tiny metal…
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Seldom Seen Slim on ‘Tautologies’ That Ain’t
Seldom Seen Slim in a characteristic back-to-the-camera pose evaluates the shooting skills of the man we call 'Doc' (in allusion to Doc Holliday). Slim writes: Whilst I'm mulling over your thoughts on souls and salvation, here's a trifle you might agree with. You write "There are many examples of the use of tautological sentences to…
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A Quiz on Alienans Adjectives
First read study the post Alienans Adjectives. Then take the quiz. Answers below the fold. Classify the adjectives in the following examples as either specifying (S), alienans (A), or neither (N). Much of course depends on the context in which the phrase is used. So imagine a plausible and common context. 1. Deciduous tree. 2. Alleged…
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Alienans Adjectives
A reader inquires: I find your blog interesting and educational. A while ago you mentioned that there is a term for an adjective which is used not to specify a particular sort of the noun which it modifies, but rather a thing which does not meet the definition of that noun. (I've likely somewhat mangled…
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When Is a Tautology Not a Tautology?
My Aunt T. was married to a gruff and taciturn Irishman who rejoiced under the name of 'Morris.' Thinking to engage Uncle Mo in conversation during one of my infrequent visits to the Big Apple, and knowing that Morris drove a beer truck, I once made some comment about the superiority of German over American…
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A Modal Fallacy to Avoid: Confusing the Necessity of the Consequence with the Necessity of the Consequent
No one anywhere can utter 'I am talking now' without saying something true. Indeed, that is necessarily the case: it doesn't just happen to be the case. Letting T = 'I am talking now,' we can write 1. Necessarily, for any speaker S, if S utters T, then T is true. But it would be…
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Validity, Invalidity, and Logical Form
When we say that an argument is valid we are saying something about its logical form. To put it epigrammatically, validity is a matter of form. We are saying that its form is such that no (actual or possible) argument of that form has true premises and a false conclusion. Validity is necessarily truth preserving.…
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The Metaphysics 101 Argument for Propositions
In his SEP entry on propositions, Matthew McGrath presents what he calls the 'Metaphysics 101' argument for propositions. Rather than quote him, I will put the argument in my own more detailed way. 1. With respect to any occurrent (as opposed to dispositional) belief, there is a distinction between the mental act of believing and…
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Logic and Meditation: Complementary Disciplines
Logic is an attempt at disciplining the discursive mind from within the discursive mind. Meditation is an attempt at transcending, by silencing, the discursive mind by using a resource that lies beyond it. Logic is disciplined thinking; meditation is disciplined nonthinking.
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Conceivability, Possibility and Per Impossibile Reasoning
Here is an example of per impossibile reasoning from Thomas Aquinas, De Veritate, q. 1, art. 2: Even if there were no human intellects, things could be said to be true because of their relation to the divine intellect. But if, by an impossible supposition [per impossibile], intellect did not exist and things did continue…
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Ataraxia and Non-Contradiction
What is the highest good? To be a bit more precise, what is the highest good attainable by us though our own (individual or collective) efforts? One perennially attractive, if unambitious, answer is that of the Pyrrhonian skeptics: our highest good lies in ataraxia. The term connotes tranquillity, peace of mind, freedom from disturbance, unperturbedness.…
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Why Be Consistent? Three Types of Consistency
A reader inquires: This idea of the necessity to be consistent seems to be the logician's "absolute," as though being inconsistent was the most painful accusation one could endure. [. . .] What rule of life says that one must be absolutely consistent in how one evaluates truth? It is good to argue from first…