<blockquote>Main Entry: <b>the·o·ry</b>
Pronunciation: 'thE-&-rE, 'thir-E
Function: noun
Inflected Form(s): plural -ries
Etymology: Late Latin theoria, from Greek theOria, from theOrein
<b>1</b> : the analysis of a set of <b>facts</b> in their relation to one another</blockquote>
Like so many others, you seem to believe that a theory is simply speculation devoid of any relation to the world around us. It is quite the opposite. A theory, involves the observation of events and phenomena over time and the extrapolation of given principles based upon those observations. They are uncertain in that, given the limitations of human perception, we can never really be certain we've observed all the phenomena from which a given theory is derived. But even events or phenomena that seem to contradict a given theory don't necessarily do so as they may require closer scrutiny. If they do indeed contradict a given theory, that theory can be re-examined, revised and, in some cases, completely scrapped and rethought in order to account for it. Such is the nature of human knowledge.