Cite as: 572 U. S. ____ (2014) 3 THOMAS, J., concurring in judgment limits entail only a “marginal” speech restriction because “[a] contribution serves as a general expression of support for the candidate and his views, but does not communicate the underlying basis for the support.” 424 U. S., at 20, 21. But this Court has never required a speaker to explain the reasons for his position in order to obtain full First Amendment protection. Instead, we have consistently held that speech is protected even “when the underlying basis for a position is not given.” Shrink Missouri, supra, at 415, n. 3 (THOMAS, J., dissenting); see, e.g., City of Ladue v. Gilleo, 512 U. S. 43, 46 (1994) (sign reading “For Peace in the Gulf ”); Texas v. Johnson, 491 U. S. 397, 415– 416 (1989) (flag burning); Tinker v. Des Moines Independent Community School Dist., 393 U. S. 503, 510–511 (1969) (black armband signifying opposition to Vietnam War); see also Colorado I, supra, at 640 (opinion of THOMAS, J.) (“Even a pure message of support, unadorned with reasons, is valuable to the democratic process”) Equally unpersuasive is Buckley’s suggestion that contribution limits warrant less stringent review because “[t]he quantity of communication by the contributor does not increase perceptibly with the size of his contribution,” and “[a]t most, the size of the contribution provides a very rough index of the intensity of the contributor’s support for the candidate.” 424 U. S., at 21. Contributions do increase the quantity of communication by “amplifying the voice of the candidate” and “help[ing] to ensure the dissemination of the messages that the contributor wishes to convey.” Shrink Missouri, supra, at 415 (THOMAS, J., dissenting). They also serve as a quantifiable metric of the intensity of a particular contributor’s support, as demonstrated by the frequent practice of giving different amounts to different candidates. Buckley simply failed to recognize that “we have accorded full First Amendment protection to expressions of intensity.” Id., at 415, n. 3; see also Cohen v. California, 403 U. S. 15, 25–26 (1971)