The fundamental component of scientific thinking is the ability to assess the 
accuracy of any claim.  Just about every conclusion we reach about our universe is 
based on incomplete information; we must infer the answers to our questions from 
whatever data we have. 

For example, we know that the Sun has risen every morning of our lifetimes, but 
how do we know it'll rise again tomorrow morning?  We must:

  - Gather data ("It has risen every morning for the past 2,000 mornings"); 
  - Judge the value of these data ("Tomorrow morning is not so different from all 
past mornings to expect the Sun's behavior to deviate from the past 2,000 
mornings"); and
  - Justify our conclusion based on that judgment ("Yes, the sun will rise 
tomorrow morning).

Although it may sound complicated, it's not.  We use our good judgment and our 
common sense all the time in our daily lives; in science, we use tools very 
similar to "our good judgment" and "our common sense" to test the validity or 
accuracy of a measurement or statement.