Kripke's Naming and Necessity showed

Nominalism

Nominalism claims only particular things exist, universals are just names

Principle of sufficient reason

Every contingent fact has a sufficient reason

Logical positivism

Logical positivism's verification principle claims only empirically verifiable statements are meaningful

the Upanishadic concept of Brahman-Atman identity claims

Brahman-Atman identity posits the individual self (Atman) is identical to ultimate reality (Brahman)

Cosmological argument

Universe's existence requires a First Cause

Rigid designator

Kripke's rigid designators refer to the same thing in all possible worlds