HAMILTON, Sir WILLIAM ROWAN (1805-1865, Irish mathematician and physicist)
The philosohy of Henry Mansel owed much to that of Sir William Stirling Hamilton (1788-1856), Scottish philosopher, who had no apparent kinship with Sir William Rowan Hamilton.
'In his Bampton Lectures on The Limits of Religious Thought (1858), Mansel applied to Christian theology the metaphysical agnosticism which seemed to result from Kant's criticism, and which had been developed in [William Stirling] Hamilton's Philosophy of the Unconditioned. While denying all knowledge of the supersensuous, Mansel deviated from Kant in contending that cognition of the ego as it really is belongs among the facts of experience. Consciousness, he held - agreeing thus with the doctrine of "natural realism" which Hamilton developed from Reid - implies knowledge both of self and of the external world. The latter, Mansel's psychology reduces to consciousness of our organism as extended; with the former is given consciousness of free will and moral obligation' (Wikipedia).
'Modern historians and philosophers have often and deeply investigated how much philosophy and poetry was essentially involved in the creation, presentation, and justification of Hamilton's mathematics, especially of his contention that algebra was properly the science of pure time. It remains, however, an open and intriguing question. What is clear is that Hamilton claimed that mathematics was akin to poetry, sought advice from his friend William Wordsworth, supported the causes of Samuel Taylor Coleridge, and cited Immanuel Kant in his work.' (Bernard Reardon, Oxford Dictionary of National Biography).
Hamilton is celebrated for his work on quaternion calculus; his quaternion theory contributed to the development of matrix algebra, vector [a word coined by him] analysis, and some graphic theory which is still used in computers and the guidance systems of space craft today, besides his contributions to discrete mathematics. He was also an astronomer and poet.