凭【píng】

凭 + noun names the basis for an action: the document that lets you in, or the quality that gets you something. In notices it's terse and formal.

With a person's ability or effort it says what got them there. 凭着 is a slightly fuller form.

只凭 says the basis is too thin.

凭什么

凭什么 challenges someone's right to do something. It's spoken and blunt.

凭 or 用

用 is for a tool or a means you physically use. 凭 is for a credential or a quality you rely on.

• × 我凭筷子吃饭 → 我用筷子吃饭
• × 他用经验知道 → 他凭经验知道