Evolution

“I know evolution is true because we see evolution happening all the time.” 

Is there a fallacy here? 

Well, my dear Watson, this does indeed smack of a logical slip-up. It's a bit like saying, "I know unicorns exist because we see horses all the time." This statement assumes that just because we see small changes or adaptations occurring in nature - what we might call "microevolution" - then "macroevolution," or the evolution of entirely new species over millions of years, must also be true. Logical? Not quite, my evolutionary enthusiast, not quite. This is an example of what we like to call the fallacy of hasty generalization. You're essentially trying to explain the mystery of the universe while only using the front cover of the book.

The fallacy of equivocation applies here.  What is evolution?  There are multiple meanings and nuances for the word, and thus makes the proposition ambiguous.  Of course things change over time, but does the statement just mean that simple truth?  Who knows?  Example:   "I'm a great student, but I did sleep  through my political science class only a 'few' times last semester!"   What is a "few?"  One or two, or perhaps a dozen?