A trusty gun might keep the mutants at bay in a nuclear post-apocalypse, but you've got to be a smooth talker if you want to barter for live-giving supplies.
Your latest look at Fallout 4's "S.P.E.C.I.A.L." stats system focuses on the C, for Charisma. A high rating gives you an edge when it comes to interpersonal skills: haggling over the price of goods, intimidating fools without ever lifting a trigger finger, pestering locals for information and even (for whatever reason) keeping addiction at bay.