If you're focusing on the spoken nature of the word:
* Silence: This is a direct contrast to the act of speaking words aloud.
* Rationality: This emphasizes a logical approach, as opposed to the mystical or ritualistic nature of an incantation.
If you're focusing on the magical or mystical aspect:
* Disbelief: This emphasizes a lack of faith in the power of words to influence events.
* Rational explanation: This emphasizes a logical and scientific explanation for events, as opposed to supernatural intervention.
* Empirical evidence: This refers to real-world evidence as opposed to relying on magical forces.
If you're focusing on the ritualistic aspect:
* Spontaneity: This emphasizes a lack of planning or structure, as opposed to the carefully structured steps of an incantation.
* Informal communication: This contrasts the formal and structured nature of an incantation.
Ultimately, the best antonym for "incantation" will depend on the specific context in which you are using the word.