Scientists use the term natural experiment to refer to situations that occur naturally, without experimental manipulation, yet allow a clean, comparative test. The fact that life events separate some but not all twins, for example, creates a natural experiment that can be used to sort out the effects of nature and nurture. But, in most cases, the only way to learn what we want to know is to design a test ourselves.
Exploration means taking action only to see what happens, without trying to make a prediction or test a hunch. An exploratory experiment is a probing, playful activity by which we get a feel for things. Exploratory experiments succeed when we are able to formulate more specific questions, or when they lead us to a hypothesis or educated guess. Then comes a more rigorous test, a confirmatory experiment, in which the objective is to learn whether the hypothesis is supported or refuted by the evidence.