ArticleslgStudy

mathematics

William Molyneux

William Molyneux is a mathematics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand William Molyneux rather than just read about it. In short: William Molyneux FRS (; 17 April 1656 – 11 October 1698) was an Anglo-Irish writer and philosopher. He is noted as a close friend of fellow philosopher John Locke, and for proposing Molyneux's problem, a thought experiment widely discussed.

William Molyneux — main illustration
William Molyneux — illustration

Key takeaways

  • William Molyneux belongs to mathematics; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect William Molyneux to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of William Molyneux from memory before moving on to harder problems.

Reference excerpt

William Molyneux FRS (; 17 April 1656 – 11 October 1698) was an Anglo-Irish writer and philosopher. He is noted as a close friend of fellow philosopher John Locke, and for proposing Molyneux's problem, a thought experiment widely discussed.

Life He was born in Dublin to Samuel Molyneux (1616–1693), lawyer, landowner and Master Gunner for Ireland, (whose grandfather, Sir Thomas Molyneux, had come to Dublin from Calais in the 1560s), and his wife, Anne, née Dowdall. The second of five children, William Molyneux came from a relatively prosperous Anglican background, with his father established at Castle Dillon in County Armagh, and his uncle Colonel Adam Molyneux holding large estates inherited from the Dowdall's in Ballymulvey, near Ballymahon in County Longford. He was close to his brother Sir Thomas Molyneux, with whom he later shared philosophical interests. His sister Jane married Anthony Dopping, the eventual Anglican Bishop of Meath. In 1671 Molyneux started at Trinity College Dublin where he became an avid reader of the leading figures of the Scientific Revolution. After attaining a Bachelor of Arts there, Molyneux was sent to study law in the Middle Temple, London from 1675 to 1678. In 1678 he married Lucy Domville (?–1691), the youngest daughter of Sir Wiliam Domville, the Attorney-General for Ireland, and his wife Bridget Lake. His wife became ill, which led to blindness after their marriage, and died young. Of their 3 children, only Samuel Molyneux (1689–1728) lived past childhood. Samuel went on to become an astronomer and politician who worked with his father on various scientific endeavours.

Career and publications Because of his inheritance, Molyneux was financially independent. Nonetheless, he held a number of official positions throughout his life. He was appointed Joint Surveyor General of the King's buildings and works in Ireland in 1684, serving alongside William Robinson. In 1687 he invented a new type of sundial called a Sciothericum telescopicum that used a special double gnomon and a telescope to measure the time of noon to within 15 seconds. He represented Dublin University in Parliament from 1692 until his death. He had also served as a commissioner of forfeited estates in 1693, resigning a few months later due to ill health. Meanwhile, Molyneux was responsible for a number of publications reflecting his diverse interests. His first book was editing and translating into English the work of René Descartes which was published in London, 1680 as Six Metaphysical Meditations, Wherein it is Proved that there is a God.... In 1682 Molyneux collaborated with Roderic O'Flaherty to collect material for Moses Pitt's Atlas. In 1685, Pitt's financial crisis lead to cancellation of the project but much valuable early Irish history had been collected. Molyneux struck a friendship with O'Flaherty and assisted when the latter's treatise Ogygia was published in London. Meanwhile, in October 1683 he founded the Dublin Philosophical Society along the lines of the Royal Society (of which Molyneux became a fellow in 1685), and became its first Secretary. He was active in the proceedings of the society—recording weather data, calculating eclipses and demonstrating instruments and experiments. Molyneux also published several papers in Philosophical Transactions, as well as papers on optics, natural philosophy, and miscellaneous topics. Perhaps his best known scientific work was Dioptrica Nova, A treatise of dioptricks in two parts, wherein the various effects and appearances of spherick glasses, both convex and concave, single and combined, in telescopes and microscopes, together with their usefulness in many concerns of humane life, are explained, published in London 1692. After John Locke published his Essay Concerning Human Understanding (1690), Molyneux wrote to him praising the work. Early in 1698, Molyneux published The Case of Ireland's being Bound by Acts of Parliament in England, Stated. This controversial work—through application of historical and legal precedent—dealt with contentious constitutional issues that had emerged in the latter years of the seventeenth century as a result of attempts on the part of the English Parliament to pass laws that would suppress the Irish woollen trade. It also dealt with the disputed appellate jurisdiction of the Irish House of Lords. Molyneux's arguments reflected those made in an unpublished piece written about 1660 by his father-in-law Sir William Domville, entitled A Disquisition Touching That Great Question Whether an Act of Parliament Made in England Shall Bind the Kingdom and People of Ireland Without Their Allowance and Acceptance of Such Act in the Kingdom of Ireland. Following a debate in the English House of Commons, it was resolved that Molyneux's publication was 'of dangerous consequence to the crown and people of England by denying the authority of the king and parliament of England to bind the kingdom and people of Ireland'. Despite condemnation in England, Molyneux was not punished but his work was condemned as seditious and was ceremonially burned at Tyburn by the public hangman. His arguments remained topical in Ireland as constitutional issues arose throughout the eighteenth century, and formed part of Swift's argument in Drapier's Letters. The tract also gained attention in the American colonies as they moved towards independence. Although The Case of Ireland, Stated was later associated with independence movements—both in Ireland and America—as one historian points out, 'Molyneux's constitutional arguments can easily be misinterpreted' and he was 'in no sense a separatist'.

Legacy

Molyneux also proposed the philosophical question that has since become known as Molyneux's problem, which Locke discussed in later editions of the Essay. The problem of the blind man who gains sight, which he proposed to Locke, is a topic that has been discussed extensively since its publication and into the 21st century. The University Philosophical Society of Trinity College Dublin views itself as the successor of the Dublin Philosophical Society, and thus recognises Molyneux as its founder and first president. Molyneux died in Dublin on 11 October 1698 and was buried in St. Audoen's Church, within the burial vault of his great-grandfather, Sir William Ussher.

References

… excerpt ends here. Continue reading the full article.

Illustrations

William Molyneux illustration
William Molyneux: Molyneux's tombstone in St. Audoen's, Dublin. It mentions his works The Case of Ireland and Dioptrica nova, his friendship with John Locke, and his son Samuel.
Molyneux's tombstone in St. Audoen's, Dublin. It mentions his works The Case of Ireland and Dioptrica nova, his friendship with John Locke, and his son Samuel.
William Molyneux: Plaque to Molyneux, at the site of the first DPS on Crow Street, Dublin
Plaque to Molyneux, at the site of the first DPS on Crow Street, Dublin
William Molyneux: Sciothericum telescopicum, or A new contrivance of adapting a telescope to a horizontal dial for observing the moment of time by day or night, 1686
Sciothericum telescopicum, or A new contrivance of adapting a telescope to a horizontal dial for observing the moment of time by day or night, 1686

Worked examples

Example 1 — a first encounter with William Molyneux

Start with the simplest possible case. Write down what William Molyneux claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to William Molyneux before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about William Molyneux ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of William Molyneux

In research
William Molyneux appears in mathematics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses William Molyneux in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
William Molyneux is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1656 births, 1698 deaths, 17th-century Anglo-Irish people, so understanding it makes those chapters shorter.
In everyday life
Look for William Molyneux outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “William Molyneux” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study William Molyneux in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what William Molyneux means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain William Molyneux out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is William Molyneux in simple terms?

William Molyneux FRS (; 17 April 1656 – 11 October 1698) was an Anglo-Irish writer and philosopher. He is noted as a close friend of fellow philosopher John Locke, and for proposing Molyneux's problem, a thought experiment widely discussed.

Why does William Molyneux matter?

Because it connects several mathematics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study William Molyneux?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on William Molyneux.

Tags

  • 1656 births
  • 1698 deaths
  • 17th-century Anglo-Irish people
  • 17th-century Irish philosophers
  • Alumni of Trinity College Dublin
  • Donegall Lecturers of Mathematics at Trinity College Dublin
  • Irish MPs 1692–1693
  • Irish MPs 1695–1699
  • Irish constitutional law
  • Irish fellows of the Royal Society
  • Irish philosophers
  • Members of the Parliament of Ireland (pre-1801) for Dublin University

Keep exploring