Four extremes

Four extremes (Skt. catuṣkoṭi; Tib. མཐའ་བཞི་, ta shyi; Wyl. mtha’ bzhi)

• existence (Wyl. yod mtha' )
• non-existence (Wyl. med mtha' )
• both existence and non-existence (Wyl. yod med mtha' )
• neither existence nor non-existence (Wyl. yod med min)

Example of this logic is for example in Nagarjuna's Mulamadhyamaka-karika, verse 55:

Everything is real and is not real,
Both real and not real,
Neither real nor not real.
This is Lord Buddha’s teaching.