Theoretical Physics is a form of Rationalism Philosophy. Rationalism is all about ‘deducing’ details of reality from first principles. In today’s Theoretical Physics, certain ‘first principles’ or ‘frameworks’ (GR and QM) have been worked out. Here ‘logical deduction’ part has been replaced by ‘Mathematical Derivation’.
There is no essential difference between deduction and derivation. Essentially, Theoretical Physics is a modern form of Rationalism Philosophy … and … as futile as its medieval counterpart.