You should set a pay range in advance and stick to it when hiring for a position. The range should be based on the skill set and experience required and what the market demands, not on what candidates you interview have earned before.
In fact, communicating in advance to candidates the pay range you’ve set can actually enhance your hiring process. It can weed out applicants who aren’t satisfied with what you’re offering. And, if you struggle to attract suitable applicants, it could alert you early that your pay range isn’t realistic.