A polymath is a person whose knowledge is not restricted to one subject area. In less formal terms, a polymathic person may simply refer to someone who is very knowledgeable. Most ancient scientists were polymaths by today’s standards.

The term Renaissance man is used to describe a person who is well educated or who excels in a wide variety of subjects or fields. This idea developed in Renaissance Italy from the notion expressed by one of its most accomplished representatives, Leon Battista Alberti that “a man can do all things if he will.” It embodied the basic tenets of Renaissance Humanism which considered man empowered, limitless in his capacities for development, and led to the notion that people should embrace all knowledge and develop their capacities as fully as possible. Thus the gifted men of the Renaissance sought to develop skills in all areas of knowledge, in physical development, in social accomplishments and in the arts.

Since it is considered extremely difficult to genuinely acquire an encyclopaedic knowledge, and even more to be proficient in several fields at the level of an expert, not to mention to achieve excellence or recognition in multiple fields, the word polymath may also be used with a potentially negative connotation as well. Under this connotation, by sacrificing depth for breadth, the polymath becomes a “jack of all trades, master of none”. For many specialists, in the context of today’s hyperspecialization, the ideal of a Renaissance man is judged to be an anachronism, since it is not uncommon that a specialist can barely dominate the accumulated knowledge of more than just one restricted subfield in his whole life, and many renowned experts have been made famous only for dominating different subfields or traditions or for being able to integrate the knowledge of different subfields or traditions.

Today, expertise is often associated with documents, certifications, diplomas, and degrees attributing to such, and a person who seems to have an abundance of these is often perceived as having more education than practical working experience. Autodidactic polymaths often combine didactic education and expertise in multiple fields with autodidactic research and experience to create the Renaissance ideal.

Many fields of interest take years of singleminded devotion to achieve expertise, often requiring starting at an early age. Also, many require cultural familiarity that may be inaccessible to someone not born and raised in that culture. In many such cases, it is realistically possible to achieve only knowledge of theory, without practical experience. For example, on a safari, a jungle native will be a more effective guide than a scientist who may be educated in the theories of jungle survival but did not grow up acquiring his knowledge firsthand.

However, those supporting the ideal of the Renaissance man today would say that the specialist’s understanding of the interrelation of knowledge from different fields is too narrow and that a synthetic comprehension of different fields is unavailable to him, or, if they embrace the Renaissance ideal even more deeply, that the human development of the specialist is truncated by the narrowness of his view. What is much more common today than the universal approach to knowledge from a single polymath, is the multidisciplinary approach to knowledge which derives from several experts from different fields collaborating together.