Is there any scientific method to assess the difference among our ideas on different things?

Answer 1

there is no right method, you'd have to make up your own.

Answer 2

It sounds like a sociology question..
I'm not a sociologist so my unqualified opinion is:

Science uses empirical observations. ie experiments
Ideas are abstract so to measure ideas would mean questioning people about introspective evaluation of their own ideas and the way they think.

Try searching for articles on Cognitive Psychology.