Eclecticism is a conceptual approach that does not hold rigidly to a single paradigm

Eclecticism is a conceptual approach that does not hold rigidly to a single paradigm or set of assumptions, but instead draws upon multiple theories, styles, or ideas to gain complementary insights into a subject, or applies different theories in particular cases. However, this is often without conventions or rules dictating how or which theories were combined.

It can sometimes seem inelegant or lacking in simplicity, and eclectics are sometimes criticized for lack of consistency in their thinking. It is, however, common in many fields of study. For example, most psychologists accept certain aspects of behaviorism, but do not attempt to use the theory to explain all aspects of human behavior.

Eclecticism in ethics, philosophy, politics and religion is also known as syncretism

Origin
Eclecticism was first recorded to have been practiced by a group of ancient Greek and Roman philosophers who attached themselves to no real system, but selected from existing philosophical beliefs those doctrines that seemed most reasonable to them. Out of this collected material they constructed their new system of philosophy. The term comes from the Greek ἐκλεκτικός (eklektikos), literally "choosing the best", and that from ἐκλεκτός (eklektos), "picked out, select".] Well known eclectics in Greek philosophy were the Stoics Panaetius and Posidonius, and the New Academics Carneades and Philo of Larissa. Among the Romans, Cicero was thoroughly eclectic, as he united the Peripatetic, Stoic, and New Academic doctrines. Philo's successor and Cicero's teacher Antiochus of Ascalon is credited with influencing the Academy so that it finally transitioned from Scepticism to Eclecticism.

Other eclectics included Varro and Seneca the Younger.

According to Rošker and Suhadolnik, however, even though eclecticism had a Greek origin, the term was rarely used and it was even given a negative connotation by historians of Greek thought, associating it with the description for impure and unoriginal thinking. Scholars such as Clement of Alexandria maintained that eclecticism had a long history in Greek philosophy and it is underpinned by a deeper metaphysical and theological conviction concerning the absolute/God as the source of all noble thoughts and that all parts of the truth can be found among the various philosophical systems

Eclecticism, (from Greek eklektikos, “selective”), in philosophy and theology, the practice of selecting doctrines from different systems of thought without adopting the whole parent system for each doctrine. It is distinct from syncretism—the attempt to reconcile or combine systems—inasmuch as it leaves the contradictions between them unresolved. In the sphere of abstract thought, eclecticism is open to the objection that insofar as each system is supposed to be a whole of which its various doctrines are integral parts, the arbitrary juxtaposition of doctrines from different systems risks a fundamental incoherence. In practical affairs, however, the eclectic spirit has much to commend it.

A philosopher, no less than a statesman, may be eclectic not on principle but because he perceives the intrinsic merit of doctrines that happen to have been advanced by opposite parties. This tendency is naturally most apt to manifest itself when established systems are losing their novelty or revealing their defects as changes of historical circumstance or scientific knowledge occur. From the beginning of the 2nd century BC, for instance, a number of philosophers professing to be attached to long-established schools—the Greek Academy, the peripatetics, or the stoics—were ready to adopt views from other schools; and Roman philosophers, in particular, to whom all Greek philosophies were enlightening, often avoided rigid partisan commitments, which even the Greeks themselves were abandoning. (Cicero was the eclectic par excellence.) It is clearly pointless to group the numerous ancient eclectics together as if they formed an eclectic school. In 19th-century France, however, Victor Cousin, a proponent of Scottish metaphysics, adopted the name éclectisme as a designation for his own philosophical system.

https://www.britannica.com/topic/eclecticism