base opinion on

base (one's) opinion on

To found or root one's view of something or someone on a particular idea or occurrence. Unfortunately, I think she based her opinion of me entirely on one wild night out together. I'm basing my opinion on the facts, and nothing else.
See also: base, on, opinion

base one's opinion on something

to make a judgment or form an opinion from something. You must not base your opinion on one bad experience. I base my opinion on many years of studying the problem.
See also: base, on, opinion