According to wiki,
Social proof (also known as informational social influence) is a psychological and social phenomenon where people assume the actions of others in an attempt to reflect correct behavior in a given situation.
I wonder what proof means in this phrase. In first impression of the phrase, I thought proof means something similar as in "waterproof", but actually it is quite the opposite. In my understanding, proof in waterproof means "immune","against", while "proof" in "social proof" means like "crave to", "prone to".
In the following possible definitions of "proof", which one is the right one for "proof" in "social proof"?
noun 1. evidence sufficient to establish a thing as true, or to produce belief in its truth. 2. anything serving as such evidence: What proof do you have? 3. the act of testing or making trial of anything; test; trial: to put a thing to the proof. 4. the establishment of the truth of anything; demonstration. 5. Law. (in judicial proceedings) evidence having probative weight. 6. the effect of evidence in convincing the mind. 7. an arithmetical operation serving to check the correctness of a calculation. adjective 18. able to withstand; successful in not being overcome: proof against temptation. 19. impenetrable, impervious, or invulnerable: proof against outside temperature changes. 20. used for testing or proving; serving as proof. 21. of standard strength, as an alcoholic liquor. 22. of tested or proven strength or quality: proof armor. 23. noting pieces of pure gold and silver that the U.S. assay and mint offices use as standards. verb (used with object) 24. to test; examine for flaws, errors, etc.; check against a standard or standards. 25. Printing. prove (def 7). 26. to proofread. 27. to treat or coat for the purpose of rendering resistant to deterioration, damage, etc. (often used in combination): to proof a house against termites; to shrink-proof a shirt. 28. Cookery. to test the effectiveness of (yeast), as by combining with warm water so that a bubbling action occurs.