The field of data science admits to many perspectives.  For William Cleveland, credited as providing one of the founding definitions of data science, there is a role for theory.   The theory --  the formal science involved -- is mostly statistical science, but it also involves the formal science of computing with data as well.  A review that focuses on the "theory" part of data science, "Data Science and the Role of Theory:  A Review of Big Data Integration Theory (2014 ) by Zoran Majkić and Category Theory for the Sciences (2014 ) by David Spivak",  is here.