Even though there are many words ending in thetical "aesthetical, antithetical, eptithetical, hypothetical, metathetical, parenthetical, pathetical" the word "thetical" itselfdoes not seem to be much used. However, it describes very precisely the pieces to be found here, each of which is driven by, and defends, some thesis.
Chapter Thirteen
And there is of course the absolutely indispensible
How do people "get" it?
which says it all---or, at least, most of it and certainly says all that is important as a first approximation. Really!