A Many-Splendored Thing
There are many formal logics! While I enjoy good old first-order logic, I've spent a great deal of time with higher-order modal logic, as evidenced by my book Gödel's God Theorem.
I am told by learned sources that logic (which one?) has something to do with “rationality.” Maybe it does!
Yet it has been my observation that logic, whichever kind you prefer, is a good servant but a poor master.