on groupthink.

If you want to know what groupthink is, ask a group of anti-groupthinkers why groupthink is such a bad thing and observe what ensues.

the parable of Frege's elephant.

To what shall we liken Frege’s view of the relations between statements, their truth, and their meanings? The truth is an elephant. Every true statement is a name for the elephant. If A and B are distinct names for the elephant, then the meanings of A and B are different aspects of the elephant—e.g. its trunk and its tail. 

on the limits of knowledge.

To what shall we liken a man who attempts to circumscribe the boundaries of the knowable? He is like a man who tells us what lies beyond the horizon even though he cannot, and therefore, has not, ventured there.  

on justifying modus ponens.

Any investigation into the “grounds” of modus ponens—viz. the justification of using the rule—will assume its validity. Therefore, such an investigation is at best hopelessly circular and at worst an exercise in defending the obvious via the dubious.

To what shall we liken the two sorts of men who attempt to justify modus ponens? Each is like a king who wishes to fortify his castle. The first king commands his subjects to remove each stone and put it back in its original place. The second king commands his subjects to rebuild the castle upon straw.

on whether things or meanings have essences.

“It is intensions, and not extensions such as individuals, that are the bearers of essential properties.” (Materna et al. 2010, p. 64)

“Things had essences, for Aristotle, but only linguistic forms have meanings. Meaning is what essence becomes when it is divorced from the object of reference and wedded to a word.” (Quine 1980, p. 22)

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Duží, M., Jespersen, B., & Materna, P. (2010). Procedural semantics for hyperintensional logic: foundations and applications of transparent intensional logic (Vol. 17). Springer Science & Business Media.

Quine, W. V. O. (1980). “Two Dogmas of Empiricism” in From a logical point of view: 9 logico-philosophical essays (Vol. 9). Harvard University Press.

on the darkness and the like.

“For now we see in a mirror, dimly…”
St. Paul, 1 Cor. 13:12

The mirror works just fine, but we can’t see ourselves because the room is too dark.
Step into the light.

Do not fear that and the darkness shall fall on you, for  
Even the night shall be light about me; 
Indeed, the darkness shall not hide from You, 
 But the night shines as the day; 
The darkness and the light are both alike to you. (Ps. 139:11-12)

there is no pure metalogic.

Let us say that an inquiry is purely metalogical just in case an inquirer makes no assumptions about the validity of any inference rule. Now suppose that a metalogical inquirer turns his gaze upon two logics which go by the names ‘classical’ and ‘intuitionist’. He observes that the former accepts the validity of double negation elimination and the latter does not. He then concludes that classical logic and intuitionist logic are not the same. Oh snap, our inquirer has left the realm of pure metalogic, for our inquirer just employed Leibniz’s Law and modus ponens. Ergo, there is no such thing as a purely metalogical inquiry.