David Hume (/hjuːm/; born David Home; 7 May 1711 NS (26 April 1711 OS) – 25 August 1776) was a Scottish Enlightenment philosopher, historian, economist, and essayist, who is best known today for his highly influential system of philosophical empiricism, skepticism, and naturalism. Hume's empiricist approach to philosophy places him with John Locke, George Berkeley, Francis Bacon and Thomas Hobbes as a British Empiricist. Beginning with his A Treatise of Human Nature (1739), Hume strove to create a total naturalistic science of man that examined the psychological basis of human nature. Against philosophical rationalists, Hume held that passion rather than reason governs human behaviour. Hume argued against the existence of innate ideas, positing that all human knowledge is founded solely in experience; Hume thus held that genuine knowledge must either be directly traceable to objects perceived in experience, or result from abstract reasoning about relations between ideas which are derived from experience, calling the rest "nothing but sophistry and illusion", a dichotomy later given the name Hume's fork.
In what is sometimes referred to as Hume's problem of induction, he argued that inductive reasoning and belief in causality cannot be justified rationally; instead, our trust in causality and induction result from custom and mental habit, and are attributable only to the experience of "constant conjunction" of events. This is because we can never actually perceive that one event causes another, but only that the two are always conjoined. Accordingly, to draw any causal inferences from past experience it is necessary to presuppose that the future will resemble the past, a presupposition which cannot itself be grounded in prior experience.
Hume's opposition to the teleological argument for God's existence, the argument from design, is generally regarded as the most intellectually significant attempt to rebut the argument prior to Darwinism.
Hume was also a sentimentalist who held that ethics are based on emotion or sentiment rather than abstract moral principle, famously proclaiming that "Reason is, and ought only to be the slave of the passions". Hume's moral theory has been seen as a unique attempt to synthesise the modern sentimentalist moral tradition to which Hume belonged, with the virtue ethics tradition of ancient philosophy, with which Hume concurred in regarding traits of character, rather than acts or their consequences, as ultimately the proper objects of moral evaluation. Hume maintained an early commitment to naturalistic explanations of moral phenomena, and is usually taken to have first clearly expounded the is–ought problem, or the idea that a statement of fact alone can never give rise to a normative conclusion of what ought to be done. Hume also denied that humans have an actual conception of the self, positing that we experience only a bundle of sensations, and that the self is nothing more than this bundle of causally-connected perceptions. Hume's compatibilist theory of free will takes causal determinism as fully compatible with human freedom.
Hume influenced utilitarianism, logical positivism, Immanuel Kant, the philosophy of science, early analytic philosophy, cognitive science, theology, and other movements and thinkers. Kant himself credited Hume as the spur to his philosophical thought who had awakened him from his "dogmatic slumbers".
Portrait by Allan Ramsay
7 May NS [26 April OS] 1711
|Died||25 August 1776 (aged 65)|
|Alma mater||University of Edinburgh|
Hume was the second of two sons born to Joseph Home of Ninewells, an advocate, and his wife The Hon. Katherine (née Falconer), daughter of Sir David Falconer. He was born on 26 April 1711 (Old Style) in a tenement on the north side of the Lawnmarket in Edinburgh. Hume's father died when Hume was a child, just after his second birthday, and he was raised by his mother, who never remarried. He changed the spelling of his name in 1734, because of the fact that his surname Home, pronounced Hume, was not known in England. Throughout his life Hume, who never married, spent time occasionally at his family home at Ninewells in Berwickshire, which had belonged to his family since the sixteenth century. His finances as a young man were very "slender". His family was not rich, and, as a younger son, he had little patrimony to live on. He was therefore forced to make a living somehow.
Hume attended the University of Edinburgh at the unusually early age of 12 (possibly as young as 10) at a time when 14 was normal. At first, because of his family, he considered a career in law, but came to have, in his words, "an insurmountable aversion to everything but the pursuits of Philosophy and general Learning; and while [my family] fanceyed I was poring over Voet and Vinnius, Cicero and Virgil were the Authors which I was secretly devouring". He had little respect for the professors of his time, telling a friend in 1735 that "there is nothing to be learnt from a Professor, which is not to be met with in Books". Hume did not graduate.
Aged around 18, he made a philosophical discovery that opened up to him "a new Scene of Thought", which inspired him "to throw up every other Pleasure or Business to apply entirely to it". He did not recount what this scene was, and commentators have offered a variety of speculations. One popular interpretation, prominent in contemporary Hume scholarship, is that the new "scene of thought" was Hume's realization that Francis Hutcheson's "moral sense" theory of morality could be applied to the understanding as well. Due to this inspiration, Hume set out to spend a minimum of 10 years reading and writing. He soon came to the verge of a mental breakdown, suffering from what a doctor diagnosed as the "Disease of the Learned". Hume wrote that it started with a coldness, which he attributed to a "Laziness of Temper", that lasted about nine months. Later, some scurvy spots broke out on his fingers. This was what persuaded Hume's physician to make his diagnosis. Hume wrote that he "went under a Course of Bitters and Anti-Hysteric Pills", taken along with a pint of claret every day. Hume also decided to have a more active life to better continue his learning. His health improved somewhat, but, in 1731, he was afflicted with a ravenous appetite and palpitations of the heart. After eating well for a time, he went from being "tall, lean and raw-bon'd" to being "sturdy, robust [and] healthful-like". Indeed, Hume would become well known in his time for his "corpulence", and his fondness for good port and cheese.
At 25 years of age, Hume, although of noble ancestry, had no source of income and no learned profession. As was common at his time, he became a merchant's assistant, but he had to leave his native Scotland. He travelled via Bristol to La Flèche in Anjou, France. There he had frequent discourse with the Jesuits of the College of La Flèche.
While Hume was derailed in his attempts to start a university career by protests over his "atheism" and bemoaned that his literary debut, A Treatise of Human Nature, 'fell dead-born from the press', he found literary success in his lifetime as an essayist, and a career as a librarian at the University of Edinburgh. His tenure there, and the access to research materials it provided, ultimately resulted in Hume's writing the massive six-volume The History of England, which became a bestseller and the standard history of England in its day. Hume described his "love for literary fame" as his "ruling passion" and judged his two late works, the so-called "first" and "second" enquiries, An Enquiry Concerning Human Understanding and An Enquiry Concerning the Principles of Morals, respectively, as his greatest literary and philosophical achievements, asking his contemporaries to judge him on the merits of the later texts alone, rather than the more radical formulations of his early, youthful work, dismissing his philosophical debut as juvenilia: "A work which the Author had projected before he left College." Despite Hume's protestations, a general consensus exists today that Hume's most important arguments and philosophically distinctive doctrines are found in the original form they take in the Treatise. Hume was just 23 years old when he started this work and it is now regarded as one of the most important in the history of Western philosophy.
He worked for four years on his first major work, A Treatise of Human Nature, subtitled "Being an Attempt to Introduce the Experimental Method of Reasoning into Moral Subjects", completing it in 1738 at the age of 28. Although many scholars today consider the Treatise to be Hume's most important work and one of the most important books in Western philosophy, the critics in Great Britain at the time did not agree, describing it as "abstract and unintelligible". As Hume had spent most of his savings during those four years, he resolved "to make a very rigid frugality supply my deficiency of fortune, to maintain unimpaired my independency, and to regard every object as contemptible except the improvements of my talents in literature". Despite the disappointment, Hume later wrote, "Being naturally of a cheerful and sanguine temper, I soon recovered from the blow and prosecuted with great ardour my studies in the country." There, in an attempt to make his larger work better known and more intelligible, he published the An Abstract of a Book lately Published as a summary of the main doctrines of the Treatise, without revealing its authorship. Although there has been some academic speculation as to who actually wrote this pamphlet it is generally regarded as Hume's creation.
After the publication of Essays Moral and Political in 1741, which was included in the later edition called Essays, Moral, Political, and Literary, Hume applied for the Chair of Pneumatics and Moral Philosophy at the University of Edinburgh. However, the position was given to William Cleghorn after Edinburgh ministers petitioned the town council not to appoint Hume because he was seen as an atheist.
During the 1745 Jacobite rising, Hume tutored the Marquess of Annandale (1720–92), who was "judged to be a lunatic". This engagement ended in disarray after about a year. However, it was then that Hume started his great historical work The History of England. This took him fifteen years and ran to over a million words. During this time he was also involved with the Canongate Theatre through his friend John Home, a preacher.
In this context, he associated with Lord Monboddo and other Scottish Enlightenment luminaries in Edinburgh. From 1746, Hume served for three years as secretary to General James St Clair, who was envoy to the courts of Turin and Vienna. At that time Hume also wrote Philosophical Essays Concerning Human Understanding, later published as An Enquiry Concerning Human Understanding. Often called the First Enquiry, it proved little more successful than the Treatise, perhaps because of the publishing of his short autobiography, My Own Life, which "made friends difficult for the first Enquiry". In 1749 he went to live with his brother in the countryside.
Hume's religious views were often suspect. It was necessary in the 1750s for his friends to avert a trial against him on the charge of heresy. However, he "would not have come and could not be forced to attend if he said he was not a member of the Established Church". Hume failed to gain the chair of philosophy at the University of Glasgow for his religious views, too. He had published the Philosophical Essays by this time which were decidedly anti-religious. Even Adam Smith, his personal friend who had vacated the Glasgow philosophy chair, was against his appointment out of concern public opinion would be against it.
Hume returned to Edinburgh in 1751. In the following year "the Faculty of Advocates chose me their Librarian, an office from which I received little or no emolument, but which gave me the command of a large library". This resource enabled him to continue historical research for The History of England. Hume's volume of Political Discourses, written in 1749 and published by Kincaid & Donaldson in 1752, was the only work he considered successful on first publication.
Eventually, with the publication of his six-volume The History of England between 1754 and 1762, Hume achieved the fame that he coveted. The volumes traced events from the Invasion of Julius Caesar to the Revolution of 1688, and was a bestseller in its day.
Hume was also a longtime friend of bookseller Andrew Millar, who sold Hume's History (after acquiring the rights from Scottish bookseller Gavin Hamilton), although the relationship was sometimes complicated. Letters between them illuminate both men's interest in the success of the History.
From 1763 to 1765, Hume was invited to attend Lord Hertford in Paris, where he became secretary to the British embassy. Hume was well received in Paris, and while there he met with Isaac de Pinto In 1766, Hume left Paris to accompany Jean-Jacques Rousseau to England. Once in England, Hume and Rousseau fell out. Hume was sufficiently worried about the damage to his reputation from the quarrel with Rousseau (who is generally believed to have suffered from paranoia) to have authored an account of the dispute, which he titled, appropriately enough "A concise and genuine account of the dispute between Mr. Hume and Mr. Rousseau." In 1765, he served as British Chargé d'affaires, writing "despatches to the British Secretary of State". He wrote of his Paris life, "I really wish often for the plain roughness of The Poker Club of Edinburgh ... to correct and qualify so much lusciousness". In 1766, upon returning to Britain, Hume encouraged Lord Hertford to invest in a number of slave plantations, acquired by George Colebrooke and others in the Windward Islands. In 1767, Hume was appointed Under Secretary of State for the Northern Department. Here he wrote that he was given "all the secrets of the Kingdom". In 1769 he returned to James' Court in Edinburgh, and then lived, from 1771 until his death in 1776, at the southwest corner of St. Andrew's Square in Edinburgh's New Town, at what is now 21 Saint David Street. A popular story, consistent with some historical evidence, suggests the street may have been named after Hume.
In the last year of his life, Hume wrote an extremely brief autobiographical essay titled "My Own Life" which summed up his entire life in "fewer than 5 pages", and notably contains many interesting judgments that have been of enduring interest to subsequent readers of Hume. The scholar of 18th-century literature Donald Seibert judged it a "remarkable autobiography, even though it may lack the usual attractions of that genre. Anyone hankering for startling revelations or amusing anecdotes had better look elsewhere." Hume here confesses his belief that the "love of literary fame" had served as his "ruling passion" in life, and claims that this desire "never soured my temper, notwithstanding my frequent disappointments." One such disappointment Hume discusses in the mini-autobiography was his disappointment that with the initial literary reception of the Treatise, which he claims to have overcome by means of the success of the Essays: "the work was favourably received, and soon made me entirely forget my former disappointment". Hume, in his own retrospective judgment, suggested that his philosophical debut's apparent failure "had proceeded more from the manner than the matter." Hume thus suggests that "I had been guilty of a very usual indiscretion, in going to the press too early." Hume provides an unambiguous self-assessment of the relative value of his works: "my Enquiry concerning the Principles of Morals; which, in my own opinion (who ought not to judge on that subject) is of all my writings, historical, philosophical, or literary, incomparably the best." Hume also makes a number of self-assessments in the essay, writing of his social relations that "My company was not unacceptable to the young and careless, as well as to the studious and literary", noting of his complex relation to religion, as well as the state, that "though I wantonly exposed myself to the rage of both civil and religious factions, they seemed to be disarmed in my behalf of their wonted fury", and professing of his character that "My friends never had occasion to vindicate any one circumstance of my character and conduct." Hume concludes the essay with the frank admission: " I cannot say there is no vanity in making this funeral oration of myself, but I hope it is not a misplaced one; and this is a matter of fact which is easily cleared and ascertained."
Diarist and biographer James Boswell saw Hume a few weeks before his death, which was from some form of abdominal cancer. Hume told him he sincerely believed it a "most unreasonable fancy" that there might be life after death. This meeting was dramatised in semi-fictional form for the BBC by Michael Ignatieff as Dialogue in the Dark. Hume asked that his body be interred in a "simple Roman tomb". In his will he requests that it be inscribed only with his name and the year of his birth and death, "leaving it to Posterity to add the Rest". It stands, as he wished it, on the southwestern slope of Calton Hill, in the Old Calton Cemetery. Adam Smith later recounted Hume's amusing speculation that he might ask Charon to allow him a few more years of life in order to see "the downfall of some of the prevailing systems of superstition." The ferryman replied, "You loitering rogue, that will not happen these many hundred years ... Get into the boat this instant".
In the introduction to A Treatise of Human Nature, Hume wrote, "'Tis evident, that all the sciences have a relation, more or less, to human nature ... Even Mathematics, Natural Philosophy, and Natural Religion, are in some measure dependent on the science of Man." He also wrote that the science of man is the "only solid foundation for the other sciences" and that the method for this science requires both experience and observation as the foundations of a logical argument. On this aspect of Hume's thought, philosophical historian Frederick Copleston wrote that it was Hume's aim to apply to the science of man the method of experimental philosophy (the term that was current at the time to imply Natural philosophy), and that "Hume's plan is to extend to philosophy in general the methodological limitations of Newtonian physics".
Until recently, Hume was seen as a forerunner of logical positivism; a form of anti-metaphysical empiricism. According to the logical positivists, unless a statement could be verified by experience, or else was true or false by definition (i.e. either tautological or contradictory), then it was meaningless (this is a summary statement of their verification principle). Hume, on this view, was a proto-positivist, who, in his philosophical writings, attempted to demonstrate how ordinary propositions about objects, causal relations, the self, and so on, are semantically equivalent to propositions about one's experiences.
Many commentators have since rejected this understanding of Humean empiricism, stressing an epistemological (rather than a semantic) reading of his project. According to this opposing view, Hume's empiricism consisted in the idea that it is our knowledge, and not our ability to conceive, that is restricted to what can be experienced. Hume thought that we can form beliefs about that which extends beyond any possible experience, through the operation of faculties such as custom and the imagination, but he was sceptical about claims to knowledge on this basis.
One of the most central doctrines of Hume's philosophy, stated in the very first lines of the Treatise, is his notion that the mind consists of its mental perceptions, or the mental objects which are present to it, and which divide into two categories: impressions and ideas. Hume's Treatise thus opens with the words: 'All the perceptions of the human mind resolve themselves into two distinct kinds, which I shall call IMPRESSIONS and IDEAS." Hume states that "I believe it will not be very necessary to employ many words in explaining this distinction" and commentators have generally taken Hume to mean the distinction between feeling and thinking. Controversially, Hume may regard the difference as in some sense a matter of degree, as he takes "impressions" to be distinguished from ideas, on the basis of their force, liveliness, and vivacity, or what Henry Allison calls the "FLV criterion" in his book on Hume. Ideas are therefore "faint" impressions. For example, experiencing the painful sensation of touching the handle of a hot pan is more forceful than simply thinking about touching a hot pan. According to Hume, impressions are meant to be the original form of all our ideas, and Don Garret has thus coined the term "the copy principle" to refer to Hume's doctrine that all ideas are ultimately all copied from some original impression, whether it be a passion or sensation, from which they derive.
After establishing the forcefulness of impressions and ideas, these two categories are further broken down into simple and complex: simple impressions and ideas, and complex impressions and ideas. Hume states that “simple perceptions or impressions and ideas are such as admit of no distinction nor separation,” while “the complex are the contrary to these, and may be distinguished into parts.” When looking at an apple, a person experiences a variety of color-sensations, which Hume sees as a complex impression. Similarly, a person experiences a variety of taste-sensations, tactile-sensations, and smell-sensations when biting into an apple, with the overall sensation again being a complex impression. Thinking about an apple allows a person to form complex ideas, which are made of similar parts as the complex impressions they were developed from, but which are also less forceful. Hume believes that complex perceptions can be broken down into smaller and smaller parts until perceptions are reached that have no parts of their own, and these perceptions are thereby referred to as being simple.
A person's imagination, regardless of how boundless it may seem, is confined to the mind's ability to recombine the information it has already acquired from the body's sensory experience (the ideas that have been derived from impressions). In addition, “as our imagination takes our most basic ideas and leads us to form new ones, it is directed by three principles of association, namely, resemblance, contiguity, and cause and effect." The principle of resemblance refers to the tendency of ideas to become associated if the objects they represent resemble one another. For example, a person looking at an illustration of a flower can conceive of an idea of the physical flower because the idea of the illustrated object is associated with the idea of the physical object. The principle of contiguity describes the tendency of ideas to become associated if the objects they represent are near to each other in time or space, such as when the thought of one crayon in a box leads a person to think of the crayon contiguous to it. Finally, the principle of cause and effect refers to the tendency of ideas to become associated if the objects they represent are causally related, which explains how remembering a broken window can make someone think of the baseball that caused the window to shatter.
Hume elaborates more on this last principle of cause and effect. When a person observes that one object or event consistently produces the same object or event, it results in “an expectation that a particular event (a 'cause') will be followed by another event (an 'effect') previously and constantly associated with it." Hume calls this principle custom, or habit, saying that “custom…renders our experience useful to us, and makes us expect, for the future, a similar train of events with those which have appeared in the past." However, even though custom can serve as a guide in life, it still only represents an expectation. In other words, “experience cannot establish a necessary connection between cause and effect, because we can imagine without contradiction a case where the cause does not produce its usual effect…the reason why we mistakenly infer that there is something in the cause that necessarily produces its effect is because our past experiences have habituated us to think in this way." Continuing this idea, Hume argues that "only in the pure realm of ideas, logic, and mathematics, not contingent on the direct sense awareness of reality, [can] causation safely…be applied – all other sciences are reduced to probability." He uses this skepticism to reject metaphysics and many theological views on the basis that they are not grounded in fact and observations, and are therefore beyond the reach of human understanding.
The cornerstone of Hume's epistemology is the problem of induction. This may be the area of Hume's thought where his scepticism about human powers of reason is most pronounced. The problem revolves around the plausibility of inductive reasoning, that is, reasoning from the observed behaviour of objects to their behaviour when unobserved. As Hume wrote, induction concerns how things behave when they go "beyond the present testimony of the senses, or the records of our memory". Hume argues that we tend to believe that things behave in a regular manner, meaning that patterns in the behaviour of objects seem to persist into the future, and throughout the unobserved present. Hume's argument is that we cannot rationally justify the claim that nature will continue to be uniform, as justification comes in only two varieties—demonstrative reasoning and probable reasoning[note 1]—and both of these are inadequate. With regard to demonstrative reasoning, Hume argues that the uniformity principle cannot be demonstrated, as it is "consistent and conceivable" that nature might stop being regular. Turning to probable reasoning, Hume argues that we cannot hold that nature will continue to be uniform because it has been in the past. As this is using the very sort of reasoning (induction) that is under question, it would be circular reasoning. Thus, no form of justification will rationally warrant our inductive inferences.
Hume's solution to this problem is to argue that, rather than reason, natural instinct explains the human practice of making inductive inferences. He asserts that "Nature, by an absolute and uncontroulable necessity has determin'd us to judge as well as to breathe and feel." Agreeing, philosopher John D. Kenyon writes: "Reason might manage to raise a doubt about the truth of a conclusion of natural inductive inference just for a moment ... but the sheer agreeableness of animal faith will protect us from excessive caution and sterile suspension of belief." Commentators such as Charles Sanders Peirce have demurred from Hume's solution, while, some, such as Kant and Karl Popper, saw that Hume's analysis "had posed a most fundamental challenge to all human knowledge claims."
The notion of causation is closely linked to the problem of induction. According to Hume, we reason inductively by associating constantly conjoined events. It is the mental act of association that is the basis of our concept of causation. There are at least three interpretations of Hume's theory of causation represented in the literature: (1) the logical positivist; (2) the sceptical realist; and (3) the quasi-realist.
Hume acknowledged that there are events constantly unfolding, humanity cannot guarantee that these events are caused by events prior or if they are independent instances. Hume opposed the widely accepted theory of Causation that 'all events have a specific course or reason.' Therefore, Hume crafted his own theory of causation, which he formed through his empiricist and skeptic beliefs. He split Causation, into two realms “All the objects of human reason or enquiry may naturally be divided into two kinds, to wit, Relations of Ideas, and Matters of Fact”. Relations of Ideas are a priori, and represent universal bonds between ideas that mark the cornerstones of human thought. Matters of Fact are dependent on the observer and experience. They are often not universally held to be true among multiple persons. Hume was an Empiricist, meaning he believed “causes and effects are discoverable not by reason, but by experience”. Hume later goes on to say that even with the perspective of the past, humanity cannot dictate future events because thoughts of the past are limited, compared to the possibilities for the future. Hume's separation between Matters of Fact and Relations of Ideas is often referred to as "Hume's fork".
Hume explains his theory of Causation and causal inference by division into three different parts. In these three branches he explains his ideas, in addition to comparing and contrasting his views to his predecessors. These branches are the Critical Phase, the Constructive Phase, and Belief. In the Critical Phase, Hume denies his predecessors' theories of causation. Next, Hume uses the Constructive Phase to resolve any doubts the reader may have while observing the Critical Phase. “Habit or Custom” mends the gaps in reasoning that occur without the human mind even realizing it. Associating ideas has become second nature to the human mind. It “makes us expect for the future, a similar train of events with those which have appeared in the past”  However, Hume says that this association cannot be trusted because the span of the human mind to comprehend the past is not necessarily applicable to the wide and distant future. This leads Hume to the third branch of causal inference, Belief. Belief is what drives the human mind to hold that expectancy of the future based on past experience. Throughout his explanation of causal inference, Hume is arguing that the future is not certain to be repetition of the past and the only way to justify induction is through uniformity.
The logical positivist interpretation is that Hume analyses causal propositions, such as "A caused B", in terms of regularities in perception: "A causes B" is equivalent to "Whenever A-type events happen, B-type ones follow", where "whenever" refers to all possible perceptions. In his Treatise of Human Nature, Hume wrote:
power and necessity ... are ... qualities of perceptions, not of objects ... felt by the soul and not perceiv'd externally in bodies.
This view is rejected by skeptical realists, who argue that Hume thought that causation amounts to more than just the regular succession of events. Hume said that when two events are causally conjoined, a necessary connection underpins the conjunction:
Shall we rest contented with these two relations of contiguity and succession, as affording a complete idea of causation? By no means ... there is a necessary connexion to be taken into consideration.
Philosopher Angela Coventry writes that, for Hume, "there is nothing in any particular instance of cause and effect involving external objects which suggests the idea of power or necessary connection" and that "we are ignorant of the powers that operate between objects". However, while denying the possibility of knowing the powers between objects, Hume accepted the causal principle, writing, "I never asserted so absurd a proposition as that something could arise without a cause."
It has been argued that, while Hume did not think causation is reducible to pure regularity, he was not a fully fledged realist either. Philosopher Simon Blackburn calls this a quasi-realist reading. Blackburn writes that "Someone talking of cause is voicing a distinct mental set: he is by no means in the same state as someone merely describing regular sequences. In Hume's words, "nothing is more usual than to apply to external bodies every internal sensation, which they occasion".
Empiricist philosophers, such as Hume and Berkeley, favoured the bundle theory of personal identity. In this theory, "the mind itself, far from being an independent power, is simply 'a bundle of perceptions' without unity or cohesive quality". The self is nothing but a bundle of experiences linked by the relations of causation and resemblance; or, more accurately, that the empirically warranted idea of the self is just the idea of such a bundle. This view is forwarded by, for example, positivist interpreters, who saw Hume as suggesting that terms such as "self", "person", or "mind" referred to collections of "sense-contents". A modern-day version of the bundle theory of the mind has been advanced by Derek Parfit in his Reasons and Persons.
However, some philosophers have criticised Hume's bundle-theory interpretation of personal identity. They argue that distinct selves can have perceptions that stand in relations of similarity and causality with one another. Thus, perceptions must already come parcelled into distinct "bundles" before they can be associated according to the relations of similarity and causality. In other words, the mind must already possess a unity that cannot be generated, or constituted, by these relations alone. Since the bundle-theory interpretation portrays Hume as answering an ontological question, philosophers, like Galen Strawson, who see Hume as not very concerned with such questions have queried whether the view is really Hume's. Instead, it is suggested by Strawson that Hume might have been answering an epistemological question about the causal origin of our concept of the self. In the Appendix to the Treatise, Hume declares himself dissatisfied with his earlier account of personal identity in Book 1. Philosopher Corliss Swain notes that "Commentators agree that if Hume did find some new problem" when he reviewed the section on personal identity, "he wasn't forthcoming about its nature in the Appendix." One interpretation of Hume's view of the self has been argued for by philosopher and psychologist James Giles. According to his view, Hume is not arguing for a bundle theory, which is a form of reductionism, but rather for an eliminative view of the self. That is, rather than reducing the self to a bundle of perceptions, Hume is rejecting the idea of the self altogether. On this interpretation, Hume is proposing a "no-self theory" and thus has much in common with Buddhist thought. On this point, psychologist Alison Gopnik has argued that Hume was in a position to learn about Buddhist thought during his time in France in the 1730s.
An essential question of practical reason for Hume was whether or not standards or principles exist (and if they do, what they are) for practical reason, that are also authoritative for all rational beings, dictating people's intentions and actions. Hume is mainly considered an anti-rationalist, denying the possibility for practical reason as a principle to exist, although other philosophers such as Christine Korsgaard, Jean Hampton, and Elijah Millgram claim that Hume is not so much of an anti-rationalist as he is just a skeptic of practical reason.
Hume denied the existence of practical reason as a principle because he claimed reason does not have any effect on morality, since morality is capable of producing effects in people that reason alone cannot create. As Hume explains in A Treatise of Human Nature (1740): “Morals excite passions, and produce or prevent actions. Reason of itself is utterly impotent in this particular. The rules of morality, therefore, are not conclusions of our reason.”
Since practical reason is supposed to regulate our actions (in theory), Hume denied practical reason on the grounds that reason cannot directly oppose passions. As Hume puts it, “Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them.” Reason is less significant than any passion because reason has no original influence, while "A passion is an original existence, or, if you will, modification of existence".
Practical reason is also concerned with the value of actions rather than the truth of propositions, so Hume believed that reason's shortcoming of affecting morality proved that practical reason could not be authoritative for all rational beings, since morality was essential for dictating people's intentions and actions.
Hume's writings on ethics began in the Treatise and were refined in his An Enquiry Concerning the Principles of Morals (1751). His views on ethics are that "[m]oral decisions are grounded in moral sentiment." It is not knowing that governs ethical actions, but feelings. Arguing that reason cannot be behind morality, he wrote:
Morals excite passions, and produce or prevent actions. Reason itself is utterly impotent in this particular. The rules of morality, therefore, are not conclusions of our reason.
Hume's moral sentimentalism about morality was shared by his close friend Adam Smith, and Hume and Smith were mutually influenced by the moral reflections of their older contemporary Francis Hutcheson. Peter Singer claims that Hume's argument that morals cannot have a rational basis alone "would have been enough to earn him a place in the history of ethics".
Hume also put forward the is–ought problem, later called Hume's Law, denying the possibility of logically deriving what ought to be from what is. He wrote in the Treatise that in every system of morality he has read, the author begins with stating facts about the world, but then suddenly is always referring to what ought to be the case. Hume demands that a reason should be given for inferring what ought to be the case, from what is the case. This because it "seems altogether inconceivable, how this new relation can be a deduction from others".
Hume's theory of ethics has been influential in modern-day meta-ethical theory, helping to inspire emotivism, and ethical expressivism and non-cognitivism, as well as Allan Gibbard's general theory of moral judgment and judgments of rationality.
Hume's ideas about aesthetics and the theory of art are spread throughout his works, but are particularly connected with his ethical writings, and also the essays Of the Standard of Taste and Of Tragedy. His views are rooted in the work of Joseph Addison and Francis Hutcheson. In the Treatise he wrote of the connection between beauty and deformity and vice and virtue, and his later writings on this subject continue to draw parallels of beauty and deformity in art, with conduct and character.
In Of the Standard of Taste, Hume argues that no rules can be drawn up about what is a tasteful object. However, a reliable critic of taste can be recognised as being objective, sensible and unprejudiced, and having extensive experience. Of Tragedy addresses the question of why humans enjoy tragic drama. Hume was concerned with the way spectators find pleasure in the sorrow and anxiety depicted in a tragedy. He argued that this was because the spectator is aware that he is witnessing a dramatic performance. There is pleasure in realising that the terrible events that are being shown are actually fiction. Furthermore, Hume laid down rules for educating people in taste and correct conduct, and his writings in this area have been very influential on English and Anglo-Saxon aesthetics.
Hume, along with Thomas Hobbes, is cited as a classical compatibilist about the notions of freedom and determinism. The thesis of compatibilism seeks to reconcile human freedom with the mechanist belief that human beings are part of a deterministic universe, whose happenings are governed by physical laws. Hume, to this end, was influenced greatly by the scientific revolution and by in particular Sir Isaac Newton. Hume argued that the dispute about the compatibility of freedom and determinism has been continued over two thousand years by ambiguous terminology. He wrote: "From this circumstance alone, that a controversy has been long kept on foot ... we may presume that there is some ambiguity in the expression", and that different disputants use different meanings for the same terms.
Hume defines the concept of necessity as "the uniformity, observable in the operations of nature; where similar objects are constantly conjoined together", and liberty as "a power of acting or not acting, according to the determinations of the will". He then argues that, according to these definitions, not only are the two compatible, but liberty requires necessity. For if our actions were not necessitated in the above sense, they would "have so little in connexion with motives, inclinations and circumstances, that one does not follow with a certain degree of uniformity from the other". But if our actions are not thus connected to the will, then our actions can never be free: they would be matters of "chance; which is universally allowed to have no existence". Australian philosopher John Passmore writes that confusion has arisen because "necessity" has been taken to mean "necessary connexion". Once this has been abandoned, Hume argues that "liberty and necessity will be found not to be in conflict one with another".
Moreover, Hume goes on to argue that in order to be held morally responsible, it is required that our behaviour be caused or necessitated, for, as he wrote:
Actions are, by their very nature, temporary and perishing; and where they proceed not from some cause in the character and disposition of the person who performed them, they can neither redound to his honour, if good; nor infamy, if evil.
Hume describes the link between causality and our capacity to rationally make a decision from this an inference of the mind. Human beings assess a situation based upon certain predetermined events and from that form a choice. Hume believes that this choice is made spontaneously. Hume calls this form of decision making the liberty of spontaneity.
Education writer Richard Wright considers that Hume's position rejects a famous moral puzzle attributed to French philosopher Jean Buridan. The Buridan's ass puzzle describes a donkey that is hungry. This donkey has on both sides of him separate bales of hay, which are of equal distances from him. The problem concerns which bale the donkey chooses. Buridan was said to believe that the donkey would die, because he has no autonomy. The donkey is incapable of forming a rational decision as there is no motive to choose one bale of hay over the other. However, human beings are different, because a human who is placed in a position where he is forced to choose one loaf of bread over another will make a decision to take one in lieu of the other. For Buridan, humans have the capacity of autonomy, and he recognises the choice that is ultimately made will be based on chance, as both loaves of bread are exactly the same. However, Wright says that Hume completely rejects this notion, arguing that a human will spontaneously act in such a situation because he is faced with impending death if he fails to do so. Such a decision is not made on the basis of chance, but rather on necessity and spontaneity, given the prior predetermined events leading up to the predicament.
Hume's argument is supported by modern-day compatibilists such as R. E. Hobart, a pseudonym of philosopher Dickinson S. Miller. However, P. F. Strawson argued that the issue of whether we hold one another morally responsible does not ultimately depend on the truth or falsity of a metaphysical thesis such as determinism. This is because our so holding one another is a non-rational human sentiment that is not predicated on such theses.
The Stanford Encyclopedia of Philosophy states that Hume "wrote forcefully and incisively on almost every central question in the philosophy of religion." His "various writings concerning problems of religion are among the most important and influential contributions on this topic." His writings in this field cover the philosophy, psychology, history, and anthropology of religious thought. All of these aspects were discussed in Hume's 1757 dissertation, The Natural History of Religion. Here he argued that the monotheistic religions of Judaism, Christianity and Islam all derive from earlier polytheistic religions. He also suggested that all religious belief "traces, in the end, to dread of the unknown." Hume had also written on religious subjects in the first Enquiry, as well as later in the Dialogues Concerning Natural Religion.
Although he wrote a great deal about religion, Hume's personal views are unclear, and there has been much discussion concerning his religious position. Contemporaries considered him to be an atheist, or at least un-Christian, and the Church of Scotland seriously considered bringing charges of infidelity against him. The fact that contemporaries thought that he may have been an atheist is exemplified by a story Hume liked to tell:
The best theologian he ever met, he used to say, was the old Edinburgh fishwife who, having recognized him as Hume the atheist, refused to pull him out of the bog into which he had fallen until he declared he was a Christian and repeated the Lord's prayer.
However, in works such as Of Superstition and Enthusiasm, Hume specifically seems to support the standard religious views of his time and place. This still meant that he could be very critical of the Catholic Church, dismissing it with the standard Protestant accusations of superstition and idolatry, as well as dismissing as idolatry what his compatriots saw as uncivilised beliefs. He also considered extreme Protestant sects, the members of which he called "enthusiasts", to be corrupters of religion. By contrast, in his The Natural History of Religion, Hume presented arguments suggesting that polytheism had much to commend it over monotheism.
Philosopher Paul Russell writes that it is likely that Hume was sceptical about religious belief, but not to the extent of complete atheism. He suggests that perhaps Hume's position is best characterised by the term "irreligion", while philosopher David O'Connor argues that Hume's final position was "weakly deistic". For O'Connor, Hume's "position is deeply ironic. This is because, while inclining towards a weak form of deism, he seriously doubts that we can ever find a sufficiently favourable balance of evidence to justify accepting any religious position." He adds that Hume "did not believe in the God of standard theism ... but he did not rule out all concepts of deity", and that "ambiguity suited his purposes, and this creates difficulty in definitively pinning down his final position on religion".
One of the traditional topics of natural theology is that of the existence of God, and one of the a posteriori arguments for this is the argument from design or the teleological argument. The argument is that the existence of God can be proved by the design that is obvious in the complexity of the world. Encyclopædia Britannica states that this is "the most popular, because [it is] the most accessible of the theistic arguments ... which identifies evidences of design in nature, inferring from them a divine designer ... The fact that the universe as a whole is a coherent and efficiently functioning system likewise, in this view, indicates a divine intelligence behind it."
In An Enquiry Concerning Human Understanding, Hume wrote that the design argument seems to depend upon our experience, and its proponents "always suppose the universe, an effect quite singular and unparalleled, to be the proof of a Deity, a cause no less singular and unparalleled". Philosopher Louise E. Loeb notes that Hume is saying that only experience and observation can be our guide to making inferences about the conjunction between events. However, according to Hume, "we observe neither God nor other universes, and hence no conjunction involving them. There is no observed conjunction to ground an inference either to extended objects or to God, as unobserved causes."
Hume also criticised the argument in his Dialogues Concerning Natural Religion (1779). In this, he suggested that, even if the world is a more or less smoothly functioning system, this may only be a result of the "chance permutations of particles falling into a temporary or permanent self-sustaining order, which thus has the appearance of design."
A century later, the idea of order without design was rendered more plausible by Charles Darwin's discovery that the adaptations of the forms of life are a result of the natural selection of inherited characteristics. For philosopher James D. Madden, it is "Hume, rivaled only by Darwin, [who] has done the most to undermine in principle our confidence in arguments from design among all figures in the Western intellectual tradition."
Finally, Hume discussed a version of the anthropic principle, which is the idea that theories of the universe are constrained by the need to allow for man's existence in it as an observer. Hume has his sceptical mouthpiece Philo suggest that there may have been many worlds, produced by an incompetent designer, whom he called a "stupid mechanic". In his Dialogues Concerning Natural Religion, Hume wrote:
Many worlds might have been botched and bungled throughout an eternity, ere this system was struck out: much labour lost: many fruitless trials made: and a slow, but continued improvement carried on during infinite ages in the art of world-making.
American philosopher Daniel Dennett has suggested that this mechanical explanation of teleology, although "obviously ... an amusing philosophical fantasy", anticipated the notion of natural selection, the 'continued improvement' being like "any Darwinian selection algorithm."
In his discussion of miracles, Hume argues that we should not believe that miracles have occurred and that they do not therefore provide us with any reason to think that God exists. In An Enquiry Concerning Human Understanding (Section 10), Hume defines a miracle as "a transgression of a law of nature by a particular volition of the Deity, or by the interposition of some invisible agent". Hume says that we believe an event that has frequently occurred is likely to occur again, but we also take into account those instances where the event did not occur. Hume wrote:
A wise man [...] considers which side is supported by the greater number of experiments [...] A hundred instances or experiments on one side, and fifty on another, afford a doubtful expectation of any event; though a hundred uniform experiments, with only one that is contradictory, reasonably beget a pretty strong degree of assurance. In all cases, we must balance the opposite experiments [...] and deduct the smaller number from the greater, in order to know the exact force of the superior evidence.
Hume discusses the testimony of those who report miracles. He wrote that testimony might be doubted even from some great authority in case the facts themselves are not credible. "[T]he evidence, resulting from the testimony, admits of a diminution, greater or less, in proportion as the fact is more or less unusual."
Although Hume leaves open the possibility for miracles to occur and be reported, he offers various arguments against this ever having happened in history: He points out that people often lie, and they have good reasons to lie about miracles occurring either because they believe they are doing so for the benefit of their religion or because of the fame that results. Furthermore, people by nature enjoy relating miracles they have heard without caring for their veracity and thus miracles are easily transmitted even where false. Also, Hume notes that miracles seem to occur mostly in "ignorant and barbarous nations" and times, and the reason they do not occur in the civilised societies is such societies are not awed by what they know to be natural events. Finally, the miracles of each religion argue against all other religions and their miracles, and so even if a proportion of all reported miracles across the world fit Hume's requirement for belief, the miracles of each religion make the other less likely.
Hume was extremely pleased with his argument against miracles in his Enquiry. He states "I flatter myself, that I have discovered an argument of a like nature, which, if just, will, with the wise and learned, be an everlasting check to all kinds of superstitious delusion, and consequently, will be useful as long as the world endures." Thus, Hume's argument against miracles had a more abstract basis founded upon the scrutiny, not just primarily of miracles, but of all forms of belief systems. It is a common sense notion of veracity based upon epistemological evidence, and founded on a principle of rationality, proportionality and reasonability.
The criterion for assessing a belief system for Hume is based on the balance of probability whether something is more likely than not to have occurred. Since the weight of empirical experience contradicts the notion for the existence of miracles, such accounts should be treated with scepticism. Further, the myriad of accounts of miracles contradict one another, as some people who receive miracles will aim to prove the authority of Jesus, whereas others will aim to prove the authority of Muhammad or some other religious prophet or deity. These various differing accounts weaken the overall evidential power of miracles.
Despite all this, Hume observes that belief in miracles is popular, and that "The gazing populace [...] receive greedily, without examination, whatever soothes superstition, and promotes wonder."
Critics have argued that Hume's position assumes the character of miracles and natural laws prior to any specific examination of miracle claims, thus it amounts to a subtle form of begging the question. To assume that testimony is a homogeneous reference group seems unwise- to compare private miracles with public miracles, unintellectual observers with intellectual observers and those who have little to gain and much to lose with those with much to gain and little to lose is not convincing to many. Indeed, many have argued that miracles not only do not contradict the laws of nature, but require the laws of nature to be intelligible as miraculous, and thus subverting the law of nature. For example, William Adams remarks that "there must be an ordinary course of nature before anything can be extraordinary. There must be a stream before anything can be interrupted". They have also noted that it requires an appeal to inductive inference, as none have observed every part of nature nor examined every possible miracle claim, for instance those in the future. This, in Hume's philosophy, was especially problematic.
Little appreciated is the voluminous literature either foreshadowing Hume, in the likes of Thomas Sherlock or directly responding to and engaging with Hume- from William Paley, William Adams, John Douglas, John Leland  and George Campbell, among others. Of Campbell, it is rumoured that, having read Campbell's Dissertation, Hume remarked that "the Scotch theologue had beaten him".
Hume's main argument concerning miracles is that miracles by definition are singular events that differ from the established laws of nature. Such natural laws are codified as a result of past experiences. Therefore, a miracle is a violation of all prior experience and thus incapable on this basis of reasonable belief. However, the probability that something has occurred in contradiction of all past experience should always be judged to be less than the probability that either ones senses have deceived one, or the person recounting the miraculous occurrence is lying or mistaken. Hume would say, all of which he had past experience of. For Hume, this refusal to grant credence does not guarantee correctness. He offers the example of an Indian Prince, who, having grown up in a hot country, refuses to believe that water has frozen. By Hume's lights, this refusal is not wrong and the Prince "reasoned justly"; it is presumably only when he has had extensive experience of the freezing of water that he has warrant to believe that the event could occur.
So for Hume, either the miraculous event will become a recurrent event or else it will never be rational to believe it occurred. The connection to religious belief is left unexplained throughout, except for the close of his discussion where Hume notes the reliance of Christianity upon testimony of miraculous occurrences. He makes an ironic remark that anyone who "is moved by faith to assent" to revealed testimony "is conscious of a continued miracle in his own person, which subverts all principles of his understanding, and gives him a determination to believe what is most contrary to custom and experience." Hume writes that "All the testimony which ever was really given for any miracle, or ever will be given, is a subject of derision."
From 1754 to 1762 Hume published The History of England, a 6-volume work, which extends, says its subtitle, "From the Invasion of Julius Caesar to the Revolution in 1688". Inspired by Voltaire's sense of the breadth of history, Hume widened the focus of the field away from merely kings, parliaments, and armies, to literature and science as well. He argued that the quest for liberty was the highest standard for judging the past, and concluded that after considerable fluctuation, England at the time of his writing had achieved "the most entire system of liberty that was ever known amongst mankind". It "must be regarded as an event of cultural importance. In its own day, moreover, it was an innovation, soaring high above its very few predecessors."
Hume's coverage of the political upheavals of the 17th century relied in large part on the Earl of Clarendon's History of the Rebellion and Civil Wars in England (1646–69). Generally, Hume took a moderate royalist position and considered revolution unnecessary to achieve necessary reform. Hume was considered a Tory historian, and emphasised religious differences more than constitutional issues. Laird Okie explains that "Hume preached the virtues of political moderation, but ... it was moderation with an anti-Whig, pro-royalist coloring." For "Hume shared the ... Tory belief that the Stuarts were no more high-handed than their Tudor predecessors". "Even though Hume wrote with an anti-Whig animus, it is, paradoxically, correct to regard the History as an establishment work, one which implicitly endorsed the ruling oligarchy". Historians have debated whether Hume posited a universal unchanging human nature, or allowed for evolution and development.
Robert Roth argues that Hume's histories display his biases against Presbyterians and Puritans. Roth says his anti-Whig pro-monarchy position diminished the influence of his work, and that his emphasis on politics and religion led to a neglect of social and economic history.
Hume was an early cultural historian of science. His short biographies of leading scientists explored the process of scientific change. He developed new ways of seeing scientists in the context of their times by looking at how they interacted with society and each other. He covers over forty scientists, with special attention paid to Francis Bacon, Robert Boyle, and Isaac Newton. Hume particularly praised William Harvey, writing about his treatise of the circulation of the blood: "Harvey is entitled to the glory of having made, by reasoning alone, without any mixture of accident, a capital discovery in one of the most important branches of science".
The History became a best-seller and made Hume a wealthy man who no longer had to take up salaried work for others. It was influential for nearly a century, despite competition from imitations by Smollett (1757), Goldsmith (1771) and others. By 1894, there were at least 50 editions as well as abridgements for students, and illustrated pocket editions, probably produced specifically for women.
It is difficult to categorise Hume's political affiliations. His writings contain elements that are, in modern terms, both conservative and liberal, although these terms are anachronistic. Thomas Jefferson banned the History from University of Virginia, feeling that it had "spread universal toryism over the land". By comparison, Samuel Johnson thought Hume "a Tory by chance ... for he has no principle. If he is anything, he is a Hobbist", a follower of Thomas Hobbes. A major concern of Hume's political philosophy is the importance of the rule of law. He also stresses throughout his political essays the importance of moderation in politics: public spirit and regard to the community.
This outlook needs to be seen within the historical context of 18th-century Scotland. Here, the legacy of religious civil war, combined with the relatively recent memory of the 1715 and 1745 Jacobite risings, fostered in a historian such as Hume a distaste for enthusiasm and factionalism. These appeared to threaten the fragile and nascent political and social stability of a country that was deeply politically and religiously divided. Hume thought that society is best governed by a general and impartial system of laws; he is less concerned about the form of government that administers these laws, so long as it does so fairly. However, he does write that a republic must produce laws, while "monarchy, when absolute, contains even something repugnant to law."
Hume expressed suspicion of attempts to reform society in ways that departed from long-established custom, and he counselled peoples not to resist their governments except in cases of the most egregious tyranny. However, he resisted aligning himself with either of Britain's two political parties, the Whigs and the Tories. Hume wrote:
My views of things are more conformable to Whig principles; my representations of persons to Tory prejudices.
Canadian philosopher Neil McArthur writes that Hume believed that we should try to balance our demands for liberty with the need for strong authority, without sacrificing either. McArthur characterises Hume as a "precautionary conservative", whose actions would have been "determined by prudential concerns about the consequences of change, which often demand we ignore our own principles about what is ideal or even legitimate." Hume supported the liberty of the press, and was sympathetic to democracy, when suitably constrained. American historian Douglass Adair has argued that Hume was a major inspiration for James Madison's writings, and the essay "Federalist No. 10" in particular.
Hume offered his view on the best type of society in an essay titled "Idea of a Perfect Commonwealth", which lays out what he thought was the best form of government. He hoped that, "in some future age, an opportunity might be afforded of reducing the theory to practice, either by a dissolution of some old government, or by the combination of men to form a new one, in some distant part of the world". He defended a strict separation of powers, decentralisation, extending the franchise to anyone who held property of value and limiting the power of the clergy. The system of the Swiss militia was proposed as the best form of protection. Elections were to take place on an annual basis and representatives were to be unpaid. Political philosophers Leo Strauss and Joseph Cropsey, writing of Hume's thoughts about "the wise statesman", note that he "will bear a reverence to what carries the marks of age". Also, if he wishes to improve a constitution, his innovations will take account of the "ancient fabric", in order not to disturb society.
In the political analysis of philosopher George Sabine, the scepticism of Hume extended to the doctrine of government by consent. He notes that "allegiance is a habit enforced by education and consequently as much a part of human nature as any other motive."
In the 1770s, Hume was critical of British policies toward the American colonies and advocated for American independence. He wrote in 1771 that "our union with America... in the nature of things, cannot long subsist".
Hume noted his views as economist in his Political Discourses, which were incorporated in Essays and Treatises as Part II of Essays, Moral and Political. To what extent he was influenced by Adam Smith is difficult to stress, however both of them had similar principles supported from historical events. At the same time Hume did not demonstrate concrete system of economic theory which could be observed in Smith's Wealth of Nations. However, he introduced several new ideas around which the “classical economics” of the 18th century was built. Through his discussions on politics, Hume developed many ideas that are prevalent in the field of economics. This includes ideas on private property, inflation, and foreign trade. Referring to his essay "Of the Balance of Trade", economist Paul Krugman has remarked that "David Hume created what I consider the first true economic model."
In contrast to Locke, Hume believes that private property is not a natural right. Hume argues it is justified, because resources are limited. Private property would be an unjustified, "idle ceremonial", if all goods were unlimited and available freely. Hume also believed in an unequal distribution of property, because perfect equality would destroy the ideas of thrift and industry. Perfect equality would thus lead to impoverishment.
Due to Hume's vast influence on contemporary philosophy, a large number of approaches in contemporary philosophy and cognitive science are today called "Humean."
Attention to Hume's philosophical works grew after the German philosopher Immanuel Kant, in his Prolegomena to Any Future Metaphysics (1783), credited Hume with awakening him from his "dogmatic slumber".
A. J. Ayer, while introducing his classic exposition of logical positivism in 1936, claimed: "The views which are put forward in this treatise derive from ... doctrines ... which are themselves the logical outcome of the empiricism of Berkeley and David Hume." Albert Einstein, in 1915, wrote that he was inspired by Hume's positivism when formulating his theory of special relativity.
Hume's problem of induction was also of fundamental importance to the philosophy of Karl Popper. In his autobiography, Unended Quest, he wrote: "Knowledge ... is objective; and it is hypothetical or conjectural. This way of looking at the problem made it possible for me to reformulate Hume's problem of induction". This insight resulted in Popper's major work The Logic of Scientific Discovery. Also, in his Conjectures and Refutations, he wrote:
I approached the problem of induction through Hume. Hume, I felt, was perfectly right in pointing out that induction cannot be logically justified.
The writings of Scottish philosopher and contemporary of Hume, Thomas Reid, were often criticisms of Hume's scepticism. Reid formulated his common sense philosophy in part as a reaction against Hume's views.
Hume influenced and was influenced by the Christian philosopher Joseph Butler. Hume was impressed by Butler's way of thinking about religion, and Butler may well have been influenced by Hume's writings.
Hume's rationalism in religious subjects influenced, via German-Scottish theologian Johann Joachim Spalding, the German neology school and rational theology, and contributed to the transformation of German theology in the age of enlightenment. Hume pioneered a comparative history of religion, tried to explain various rites and traditions as being based on deception and challenged various aspects of rational and natural theology, such as the argument from design.
Danish theologian and philosopher Søren Kierkegaard adopted "Hume's suggestion that the role of reason is not to make us wise but to reveal our ignorance." However, Kierkegaard took this as a reason for the necessity of religious faith, or fideism. The "fact that Christianity is contrary to reason ... is the necessary precondition for true faith." Political theorist Isaiah Berlin, for example, has pointed out the similarities between the arguments of Hume and Kierkegaard against rational theology. Berlin also writes about Hume's influence on what Berlin calls the counter-enlightenment, and German anti-rationalism.
The Stanford Encyclopedia of Philosophy writes that Hume is "[g]enerally regarded as one of the most important philosophers to write in English."
His nephew and namesake, David Hume of Ninewells (1757–1838), was a co-founder of the Royal Society of Edinburgh in 1783. He was a Professor of Scots Law at Edinburgh University and rose to be Principal Clerk Of Session in the Scottish High court and Baron of the Exchequer. He is buried with his uncle in Old Calton Cemetery.