Four extremes

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

• existence (ཡོད་མཐའ་, Wyl. yod mtha' )
• non-existence (མེད་མཐའ་, Wyl. med mtha' )
• both existence and non-existence (ཡོད་མེད་མཐའ་, Wyl. yod med mtha' )
• neither existence nor non-existence (ཡོད་མེད་མིན་, 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.