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.
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 Skepticism 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.