Can external validity & internal validity affect each other?

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Research Methods: Which is more important: external validity, internal validity, or a balance between the two?
Explain why. How can external validity and internal validity affect one another?

External validity means that the experiment conforms closely to the natural conditions in the world and so the results would be expected to be generalizable to situations outside of the experimental conditions. In other words, what you find would be expected to be true in the "real world" outside of the experiment design.

Internal validity means that the cause and effect or relationships between variables are clearly controlled so that what you find is not contaminated by other variables. High internal validity comes when you are able to isolate the effects of a particular variable carefully enough that you can conclude that other influences ...