This document discusses the Buddhist philosophical concept of Catuṣkoṭi and how it relates to logic, set theory, and quantum mechanics. Catuṣkoṭi considers four possibilities - A, not A, both A and not A, and neither A nor not A. This differs from binary Aristotelian logic. The document uses examples from the King Devadatta story and set theory to illustrate issues resolved by Catuṣkoṭi but not binary logic. It argues that developments in quantum mechanics support concepts expressed by Catuṣkoṭi, suggesting it remains relevant despite claims it is dead. References for further information on Catuṣkoṭi and related

1. Catuṣkoṭi
චතුස්කකෝටිකය - Tetralemma

2. Aristotelian logic (Binary
Logic)
A Not-A
ද්විකකෝටිකය

3. Aristotelian logic
• Logic of Modern Science
• Studied in Mathematics, Philosophy,
Computer Science and Arts
• Independent of the Observer (Objective
Reality)

4. Catuṣkoṭi
A Not-A
Both A & Not-A Neither A Nor Not-A

5. Relation Problem (නෑදෑ ප්රශ්නය)
Mihindu Thero: Great King, Do you have relatives?
(මහරජ, ඔබට නෑකයෝ සිටිත්ද?)
King Dev: Yes, Venerable Sir. ( එකසේය ස්වාමීනි.)
Mihindu Thero: Great King, Do you have non-
relatives? (මහරජ, ඔබට කනොනෑකයෝ සිටිත්ද?)
King Dev: Yes, Venerable Sir. (එකසේය ස්වාමීනී.)

6. Relation Problem (නෑදෑ ප්රශ්නය)
Mihindu Thero: Great King, Is there anyone
that is not a relative or yours nor a non-
relative of yours? (මහරජ, එකසේ නෑකයෝත්
කනොවන, කනොනෑකයෝත් කනොවන තවත් අය
සිටිත්ද?)
King Dev: Yes, Venerable Sir. That is me.
(එකසේය ස්වාමීනී. ඒ මමය.)

7. Relation Problem in Set Theory
• Where do we put the King????
All
Humans
Non-
Relatives
Relatives

8. Catuṣkoṭi
in our culture
• “යන එන ගමන්” - coming “and” going
• “අඩු වැඩිය” - more “and” less
• Attitudes
• Gestures

9. Chatuṣkoṭi in Buddhist Philosophy
• නත කසෝ නත අඤ්කඤෝ - (the one who is
reborn) is not the same person nor is
another.
• In Aristotelian Logic this is impossible.
• In Catuṣkoṭi this is possible.

10. Is Chatuṣkoṭi Dead?
• Quantum Mechanics (Wave-Particle
duality)
• Copenhagen interpretation (Heisenberg's
uncertainty principle)
• Quantum Computing (Qubit)
• Reality?

11. References
• 1963 Early Buddhist Theory of Knowledge. – K.N.
Jayatillake, Publisher: George Allen and Unwin.
• Concept and Reality in Early Buddhist Thought – Ven.
Katukurunde Knanananda
http://www.seeingthroughthenet.net/files/eng/books/other/concept_and_reali
ty.pdf
• The Magic of the Mind – Ven. Katukurunde Knanananda
http://www.seeingthroughthenet.net/files/eng/books/other/the_magic_of_the
_mind.pdf
• අකප් ප්‍රවාද 1, 2, 3 (Our theories) - Nalin De Silva

12. Thank You.