What did the verification principle say about when a statement is meaningful?

In the context of modern philosophy, the verifiability principle—a cornerstone of logical positivism—asserts that a statement is cognitively meaningful only if it meets one of two conditions:

• It is empirically verifiable, meaning its truth or falsehood can be determined (at least in principle) through observation, experience, or scientific experiment.123
• It is tautological, meaning its truth is derived entirely from the definitions and meanings of its own terms.3

According to this principle, statements that are neither empirically verifiable nor tautological—such as those found in metaphysics, ethics, aesthetics, or religion—are considered literally meaningless in a cognitive sense. While such expressions may still hold significance by influencing emotions, beliefs, or conduct, they do not impart factual knowledge.234

The principle was intended to clarify scientific language by distinguishing between factual assertions and non-cognitive expressions, though it faced significant criticism for being unverifiable itself.345