The Logic of Thought

Is he willing to prevent evil, but not able?
Then, he is impotent.
Is he able, but not wiling?
Then he is malevolent.
Is he both able and willing?
Then, where does evil come from?

Philo on the Questions of Epicurus made in reference to God’s relationship with evil. 1

Epicurus (341 - 270 B.C.)
Epicurus (341 – 270 B.C.)

All communication begins with a desire to communicate. A successful communication is one that creates in the mind of the receiver the part of the idea or feeling that resides in the mind of the sender, and that the sender wishes the receiver to know.

How this communication takes place depends on the channel, formatlanguage, and protocol mutually selected by those desirous of the communication. Each language has its own mutually recognized set of symbols and rules, and these symbols and rules vary, often significantly, from language to language.

The way in which these mutually agreed symbols are organized in a message depends on two kinds of logic: the logic of the message that is largely independent of the language used, and the logic of the mutually agreed language to whose rules and symbols both parties to the communication must agree, else the communication fails, — namely, the logic of the language or grammar. That I can send the same message in four different languages, using four very different sets of symbols and grammatical rules goes a very long way to explain the separation of these two kinds of logic.

To the extent that the logic of a message is universal, however, depends on the cultural upbringing of the sender and the receiver.  Indeed, the same symbol can be interpreted differently across different cultures, and how the symbols of each culture are arranged in the minds of the individual members of the same culture also varies.  Further, culture and technology play an important role in the establishment of proper protocol, format, and channel — the rules and constraints for establishing and conducting good communication.  Thus, we can speak of a third logic that depends not only on a mutually shared culture, but also mutually, or at least, commonly shared experience. This can be called cultural or contextual logic.

In what follows we will combine the notions of contextual logic and the logic of the message into a single logic called conceptual logic and contrast this with the logic of the language (grammatical logic) — namely, the rules by which the symbols of a language are organized within the language to transmit the conceptual logic of the message.  When differences in the contextual logic of the sender and receiver become important we will separate these from the more universal logic of the message that humans tend to understand across all cultures by virtue of their being human.


  1. Excerpt from a conversation between Cleanthes and Philo in a letter from Pamphilus to Hermippus.  Philo, Cleanthes, Pamphilus, and Hermippus appear to be fictional characters invented by David Hume (1711-1776) in his Dialogues Concerning Natural Religion, Part 10, p.48. Edited by Jonathan Bennett, November 2010-2015. <‎online document>