For a test of open-mindedness, see Essay:Quantifying Openmindedness.
Saying someone lacks an open mind is often used pejoratively, for example, "Don't be pro-life/pro-marriage/pro-abstinence, be open-minded. In this context, "open minded" simply means considering a certain viewpoint.
- "It is the mark of an educated mind to be able to entertain a thought without accepting it." (Aristotle)