James Logan apprenticed with a Dublin-based linen draper, received a good classical and mathematical education, and acquired a knowledge of modern languages not common at the period.

The War of 1689–91 obliged him to follow his parents, first to Edinburgh, and then to London and Bristol, England where, in 1693, James replaced his father as schoolmaster.

He had a good complexion, and was quite florid, even in old age; nor did his hair, which was brown, turn grey in the decline of life, nor his eyes require spectacles.

"[4] Logan supported proprietary rights in the colonial-era Province of Pennsylvania and became a major landowner in the growing colony; he was also a slave-owner.

[6][7] Logan advanced through several political offices, including clerk (1701), commissioner of property (1701), receiver general (1703), and member of the provincial council (1703).

During his tenure as mayor, Logan allowed Irish Catholic immigrants to participate in the city's first public Mass.

[12] The net result of the Walking Treaty was an increase in the colony's size of over 1,200,000 acres, the scattering of the Lenape in a regional diaspora, and the breakdown of diplomatic relations between Pennsylvania and the tribe.

[12][13] Throughout his life in the Province of Pennsylvania, Logan engaged in various mercantile pursuits, especially fur trading, with such success that he became one of the wealthiest men in the Thirteen Colonies.

Logan was also a natural scientist whose primary contribution to the emerging field of botany was a treatise that described experiments on the impregnation of plant seeds, especially corn.

[15][16] Logan would in time become known to Benjamin Franklin and his "Junto"; an influential group of friends that would meet weekly and discuss scholarly and political issues.

He became a mentor to Franklin, who published Logan's translation of Cicero's essay "Cato Maior de Senectute".

[18] Franklin and the other members of the Junto considered Logan the "best Judge of Books in these parts"[19] and chose him to select the first 43 titles for the Library Company of Philadelphia.

Unconvinced, Logan wrote his agent in London, explaining that he had sold his library to a bookseller who lived on Castle Street and to see if he knew of the book's location.

His 1730 estate Stenton in the Logan neighbourhood has been named a National Historic Landmark and operates as a public museum.