Why did W.V.O. Quine question the distinction between analytic and synthetic statements?

In his seminal 1951 essay, "Two Dogmas of Empiricism," W.V.O. Quine challenged the traditional analytic-synthetic distinction, which categorized statements as either true by definition (analytic) or true by empirical fact (synthetic).12

Quine questioned this division for several key reasons:

• Lack of Necessity: He argued that the distinction is ill-founded because it is not required by any adequate psychological or scientific account of how theories are formulated.3
• Degree, Not Kind: Quine contended that the difference between analytic and synthetic statements is one of degree rather than kind. He proposed that scientific knowledge functions like a "web" of belief; no statement is inherently immune to revision in the face of "recalcitrant experience," provided other adjustments are made elsewhere in the system.124
• Indeterminacy of Meaning: Quine doubted the coherence of concepts like synonymy (sameness of meaning), which are necessary to define analyticity. He argued that empirical evidence is insufficient to determine the precise meaning of words, leading to his conclusion that there is no "fact of the matter" regarding meaning.245

Ultimately, Quine rejected the distinction because he believed it failed to provide a clear, objective basis for separating logic from empirical science.25