No geologist would ever (or likely will ever) say that we &quot;really know how the Earth works&quot;.  I say this as a geologist, and I can&#x27;t imagine any other geologist disagreeing.<p>The natural sciences are incredibly complex.  You&#x27;re not dealing with nice simple interactions, and we can&#x27;t run experiments on the time, spatial, or energy scales needed to directly test hypotheses in the way you would in an experimental science.<p>Instead, we observe.<p>We try to understand the present to understand the past and the past to understand the present.<p>When you&#x27;re observing an uncontrolled system, it&#x27;s very tough to isolate one variable from another.  Geology is often accused of not being &quot;quantitative enough&quot;.  What people don&#x27;t realize is that the quantitative part is usually stupidly easy.  It&#x27;s choosing the right physics to model that&#x27;s hard.  We usually don&#x27;t fully understand exactly which physical process are at work.