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Wednesday 20 May 2015

Philosophers and coffee, a romance

(Reproduced from Facebook note)

David Hume

Hume's career was sidelined and sabotaged by the religionist elite in the academy due to his atheism and scepticism, and due to his effective attack on Rene Descartes' philosophy of the unreliability of the senses and of the material sciences for gaining knowledge. However, he still wrote some of the greatest works of philosophy, and was also an excellent and well respected writer about history and politics in England.

Hume was also a fan of backgammon and coffee, and frequented coffee houses where he gave impromptu tutorials with students and the general public. His interest in coffee culture was far reaching. In 1752 he wrote his political discourses, in which he expressed:


 An author is little to be valued, who tells us nothing but what we can learn from every coffee-house conversation.

However, Hume frequented coffee houses, as had his father before him - Henry Home (the original spelling of Hume's name, which he changed because the English had trouble pronouncing it). Hume had a friendship with the French Romantic writer and philosopher Jean Jacques Rousseau, and their meetings in Parisienne coffee houses is a matter of historical note.

In his History of England, Hume mentions King Charles' capitulating response to a petition from coffee sellers and coffee houses, in exchange for fealty:

The law, which settled the excise, enacted, that licences for retailing liquors might be refused to such as could not find security for payment of the duties. But coffee was not a liquor subjected to excise; and even this power of refusing licences was very limited, and could not reasonably be extended beyond the intention of the act. The king, therefore, observing the people to be much dissatisfied, yielded to a petition of the coffee-men, who promised for the future to restrain all seditious discourse in their houses; and the proclamation was recalled. 
Rousseau

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Jean Jacques Rousseau (
1712-1778)


Rousseau, with whom Hume had a fast friendship and then a falling out, also developed a friendship with French writer Bernadin de St Pierre. In his memoirs St Pierre recalls the following of a meeting with Rousseau:

As I accompanied him back across the Tuilleries, we perceived a smell of coffee. "There," said he," is a perfume, of which I am very fond. When the other lodgers in the house where I live burn their coffee, my neighbours shut their doors to keep out the smell, but I open mine." " Then you are fond of coffee," said I. "Yes," said he," ices and coffee are almost the only luxuries for which I have a taste." I had brought with me from the isle of Bourbon a bale of coffee, and had made up several parcels for presents to my friends. (, NORTH AMERICAN REVIEW.No. XXXVI.NEW SERIES, No. XI.JULY 1822. p4, <http://www.jstor.org/stable/25109134?seq=1#page_scan_tab_contents>) 

au

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(François Marie Arouet de) Voltaire (1694-1778)


In his "All About Coffee" William Ukers says of a famous Parisienne coffee house:

Because of its location, the Café de Procope became the gathering place of many noted French actors, authors, dramatists, and musicians of the eighteenth century. It was a veritable literary salon. Voltaire was a constant patron; and until the close of the historic café, after an existence of more than two centuries, his marble table and chair were among the precious relics of the coffee house. His favorite drink is said to have been a mixture of coffee and chocolate. Rousseau, author and philosopher; Beaumarchais, dramatist and financier; Diderot, the encyclopedist; Ste.-Foix, the abbé of Voisenon; de Belloy, author of the Siege of Callais; Lemierre, author of Artaxerce; Crébillon; Piron; La Chaussée; Fontenelle; Condorcet; and a host of lesser lights in the French arts, were habitués of François Procope's modest coffee saloon near the Comédie Française.

Voltaire

And Voltaire is rumoured to have consumed 40-50 cups of coffee a day. Some physicians of his day described coffee as a "slow poison", and Ukers notes that:

Fontenelle and Voltaire have both been quoted as authors of the famous reply to the remark that coffee was a slow poison: "I think it must be, for I've been drinking it for eighty-five years and am not dead yet."

au

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Sartre

Jean-Paul Sartre
The Marxist existentialist philosopher Jean-Paul Sartre conducted philosophical discussions at the Café de Flore. Called "coffee/cafe philos", they were the forerunner to and inspiration for Trotskyist Marc Sautet's "cafés-philos".

Wednesday 6 May 2015

Physicalist Information Realist Moment: Burns Bay, Lane Cove West

Observations from physicalist information theory and physical realist philosophy of information:
  1. A subjectivist about information (someone who thinks that information requires - or existentially depends upon - a subjective observer or signal-receiving and processing agent) has to explain why the the photons reflecting from the environment of the water's surface is necessarily any less storage of structural information than their mental representation (reducing to the processing of signals in the retinotopic map, perhaps) and the interaction between the two. They must explain why the green in the reflection is not providing information originating in the DNA in the tree, and why this in turn is not objectively existing structured information that would still be there without any observers.
  2. An eliminitavist about information (information is not some thing in the world - just a label we use for when objective frequentist probabalistic uncertainty is reduced for an observer)  has to answer the same challenge.
This argument is not intuitive argument, but RAA. If subjectivism and eliminativism are correct, then there is nothing that we would normally call information in the DNA of trees. That seems simply wrong.









Existential Moments #2: Fletcher Lookout

As an information theorist and philosopher of information I can make the following observations:

The camera captures only a tiny part of the physical and structural information in the environment - much less than what the ocular organs capture. The camera of course stores its information far more permanently and accurately (although perhaps as an artificial electrically operated digital device its lifespan is limited by bit corrosion and technology redundancy to less than the lifespan of my memories).




Existential Moments #1: Wentworth Falls and the Slack Stairs

When looking out over the Blue Mountains, and especially when hugging the rock on the Slack Stairs climb, Bishop Berkeley starts to look pretty stupid. Really.


From Wentworth Falls Lookout




From Wentworth Falls Lookout: E-NE

From Fletcher Lookout

From Wentworth Falls Lookout

Rocket Point Lookout Towards the Falls

Mid Slack Stairs

Mid Slack Stairs

Under Mid Slack Stairs

Web. No resident visible.

Slack Stairs: Fern

Up at Lower Wentworth Falls from below Slack Stairs and to the East.

Lower Wentworth Falls and Lagoon from below Slack Stairs and to the East.

Lower Wentworth Falls from below Slack Stairs and to the East.

Slack Stairs Cutting

Slack Stairs Cutting Looking Up


Panoramic from Wentworth Falls Lookout.



David Hume for Novice Philosophers. Part II: Religionism in The Academy, Sceptical Limits on Naturalistic Empiricism, and Backgammon

Hume

At the beginning of his academic career, Hume spent time debating Jesuits of the college of La Flèche, where he spent much of his savings during the 4 years there writing “A Treatise of Human Nature”. This marked the beginning of Hume's career of undermining religious thought and belief. Hume is understood to have been opposed to religious enthusiasm, but otherwise often taken to be a believer. 

However, he was later in his career defended against charges of heresy by claims that, as an atheist, Church law did not apply to him. Moreover, his scepticism clearly targets any claims that a god being could be known in any other way than by repeated sense based experience, such that ontological arguments for the existence of a god relying upon a-priori concepts and reasoning cannot stand.

In contrast to Hume's scepticism about certainty about objects of faith, the other two famous Empiricist philosophers were Hume's predecessor John Locke, and his contemporary Bishop George Berkeley, both of whom were also Christians and theologians - particularly Berkeley. This gives one a sound impression of the ongoing strength of representation of Judeo Christian religion in the academy and academic institutions of the time. Hume was all but surrounded by clerics and devouts who thought that the character of God in the Christian Bible represented a real being, and whose peers and allies would tend to aggressively undermine any alternative narratives and commentaries as explanations of life and human existence, and with no real regard for strength of argument or reason.

Berkeley's Empiricism was also underpinned by scepticism. However, Berkeley's scepticism about the reliability of the senses was even stronger than that of Descartes. It led him to Idealism, according to which ideas and the mind are all that exists, and according to which there is in fact no external world at all outside of the mind. All of existence was in fact an idea in the mind of the Biblical character of God - whom Berkeley believed to be a real supernatural entity. (It is not difficult to trace Descartes commitment to the existence of an external world as the creation of the god being that he also believed to exist, since his brain-mind dualism is based upon a metaphysical dualism that regards mind as constituted of real 'spooky mind stuff' that is not the same as the real material stuff that the body is made of.)

Berkeley
Berkeley and Hume were both interested in John Locke's dictum that ideas are representations of objects that cause them via either sense or internal reflection, but that there is no way to know that the objects exist: only the representing ideas. So as with Hume after him, Locke assumes the existence of the external mind-independent world, but recognises that ideas are what is apparent to the mind, and that the mind cannot get past the representing idea to the actual object.
Locke


Unlike Hume and Locke, Berkeley bites the bullet on the inability of the mind to directly perceive any external object, and simply asserts that such things don't really exist apart from perceptions/ideas of persons and in the mind of the Biblical God character whom he believed to be real. (It is somewhat of a puzzle how it can be the case even for Berkeley that the god being he believed existed would not have to be an external entity and not an idea in Berkeley's own mind, but that is another matter). This leads him to his principle of Idealism - esse est percipi: existence is perception or to be is to be perceived. This involves a much stronger scepticism about the senses and their role in knowledge production than that of even Descartes who simply doubts the ability of the senses to provide reliable information and thence knowledge.

Hume rejects Berkeley as effectively solipsistic, and regards that experience is of some external reality, and does not see the entire concept of experience and sense experience as meaningful otherwise. A keystone of both Descartes, Locke, and Berkeley's view is the impression and idea of the reality of the self, and Hume attacks any certainty about this concept outright as circular in A Treatise:
“If any impression gives rise to the idea of a self, that impression must continue invariably the same through the whole course of our lives, since the self is supposed to exist in that manner. But there is no impression constant and invariable. Pain and pleasure, grief and joy, passions and sensations succeed each other and never all exist at the same time. It cannot therefore be from any of these impressions or from any other that the idea of the self is derived, and,consequently there is no such idea. (
A Treatise of Human Nature, 164. https://www.gutenberg.org/files/4705/4705-h/4705-h.htm)
More devastatingly, as indicated in parentheses two paragraphs above, Hume points out that there does not seem to be any way that Berkeley can claim that the god being whose mind is supposed to sustain all of existence is not in fact just an idea in Berkeley's mind. A vicious circularity in both explanatory, conceptual, and metaphysical terms arises, which circularity is arguably simply not recoverable for Berkeley.

However, Hume's scepticism as expressed in both the problem of induction and the inability to truly know the real fact of the matter in causal relations was strong enough to cause his empiricist conclusions serious difficulty. He can't get past his simple and complex sense impressions to causal relations or to external objects either. He has dispensed with a-priori reasoning for the task, and has only probable knowledge based upon regular experiences, which cannot present the detailed nature of causal relations or give the mind access to external objects except by assumption that there is an external nature to be experienced and that the information intuitively associated with it could not come from anywhere else. Any real regularities in nature - and perhaps nature itself - have to remain the consequence of an intuitive assumption supported by and about repetitive experiences. This overpowering of even synthetic a-posteriori reason by his scepticism di not dislodge Hume's naturalism, but did lead Hume to openly brood darkly:
The intense view of these manifold contradictions and imperfections in human reason has so wrought upon me, and heated my brain, that I am ready to reject all belief and reasoning, and can look upon no opinion even as more probable or likely than another. Where am I, or what? From what causes do I derive my existence, and to what condition shall I return? Whose favour shall I court, and whose anger must I dread? What beings surround me? and on whom have, I any influence, or who have any influence on me? I am confounded with all these questions, and begin to fancy myself in the most deplorable condition imaginable, inviron'd with the deepest darkness, and utterly depriv'd of the use of every member and faculty. (Treatise 1.4.7.8)
Hume's response is to distract himself with living, eating, and playing backgammon so that the darkness fades. (Treatise 1.4.7.9)

In his attacks on the doctrines of Descartes and Berkeley, Hume takes some care not to bruise theological and general religious sensibilities too openly, although as we will see in part III not so carefully as to avoid expulsion and lifetime exclusion from the academy as a working and tenured philosopher. He clearly places empirical detection of entities as a necessary condition for existence claims:
The existence, therefore, of any being can only be proved by arguments from its cause or its effect; and these arguments are founded entirely on experience. If we reasonà priori, any thing may appear able to produce any thing. The falling of a pebble may, for ought we know, extinguish the sun; or the wish of a man controul the planets in their orbits. It is only experience, which teaches us the nature and bounds of cause and effect, and enables us to infer the existence of one object from that of another035. Such is the foundation of moral reasoning, which forms the greater part of human knowledge, and is the source of all human action and behaviour. (Hume, D. Enquiry Section XII Part 3, http://www.davidhume.org/texts/ehu.html, E 12.29)


Hume's rejection of Descartes' certainty about self and about the existence of the Christian god character as real, his rejection of Berkeley's idealism, and his emphasis on the impossibility of knowing about anything except for a-posteriori synthetically on an empirical basis: these were probably enough to see his end as an endorsed philosopher in the academy. However, as has been alluded to already, Hume launched a concerted philosophical attack on human testimony - especially religiously inspired testimony, which is of course the stuff of religious texts.




In An Enquiry, after delivering four arguments that human testimony about miracles must be regarded as unreliable, he concludes:

The plain consequence is (and it is a general maxim worthy of our attention), “That no testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous, than the fact, which it endeavours to establish: And even in that case there is a mutual destruction of arguments, and the superior only gives us an assurance suitable to that degree of force, which remains, after deducting the inferior.” (Hume, D. An Enquiry Concering Human Understanding Section XII Part 3, http://www.davidhume.org/texts/ehu.html, E 12.29)

In short, not only does Hume’s empiricism say that even if there was really a god of kind claimed in Judeo-Christian texts it would be impossible to have any knowledge about them as a fact on a probable basis (the only available basis) since they are unavailable to experience, but human testimony about miracles or supernatural intervention is dramatically less reliable than empirical observation of nature. In fact it is wholly unreliable where the falsity of the testimony would be more surprising than the miracle claimed on an empirical basis.

The intention is that since all miracles are more miraculous than the prospective falsehood of their testimonies, the testimonies are probably false. In other words, if using reason related to our empirical knowledge of how flawed the testimony of human beings is, the miracle testified to is less surprising than the falsehood of the testimony would be, then reject the testimony. In still other words: reject testimony all the time if it is about a miracle that requires us to override knowledge based upon our empirical experience of nature - even if that is only probable in nature.

Put yet another way: we can know facts of the world and nature as probably the case only, and testimony that contravenes or contradicts that empirical knowledge - claiming miracles for example - is unlikely to be true since it is less probable by dint of empirical understanding of the reliability of human testimony about unlikely events. This is, of course, applicable to entire religious texts that are taken to be miraculous and supernaturally inspired.

A direct consequence of Hume’s skeptical empiricism is that you couldn’t know anything about any kind of supernatural god by testimony, and you can’t rely on any written or spoken reports of miracles. Theses are not happy outcomes for theists and Hume’s theological sparring partners. As we will see – they preferred to torpedo his career rather than deal with the arguments.

Tuesday 5 May 2015

David Hume for Novice Philosophers. Part I: Sceptical Empiricist and Philosophical Naturalist

David Hume



Bruce R Long B App Sc. (Computing), BA Hons 1 (Philosophy), MPhil (Eng.) PhD candidate (Analytic Philosophy) 

Although one of the most renowned of the British empiricist philosophers, David Hume is best known for his scepticism, the metaphysical and epistemic implications of which have been debated by philosophers since Kant (who opposed Hume's metaphysics and moral theories strenuously on behalf of Protestant patrons and their theist doctrine). The best and most famous example of Hume's scepticism is his view of causality.

Hume asserted that we could never be certain that a particular kind of physical effect would always follow from the same kind of physical cause. The next time you drop something, gravity might behave anomalously and the object might go sideways. This is referred to as the problem of induction:
But to convince us, that all the laws of nature, and all the operations of bodies without exception, are known only by experience, the following reflections may, perhaps, suffice. Were any object presented to us, and were we required to pronounce concerning the effect, which will result from it, without consulting past observation; after what manner, I beseech you, must the mind proceed in this operation? It must invent or imagine some event, which it ascribes to the object as its effect; and it is plain that this invention must be entirely arbitrary. The mind can never possibly find the effect in the supposed cause, by the most accurate scrutiny and examination. For the effect is totally different from the cause, and consequently can never be discovered in it. Motion in the second Billiard-ball is a quite distinct event from motion in the first; nor is there any thing in the one to suggest the smallest hint of the other. A stone or piece of metal raised into the air, and left without any support, immediately falls: But to consider the matter a priori, is there any thing we discover in this situation, which can beget the idea of a downward, rather than an upward, or any other motion, in the stone or metal?(Hume, D. Enquiry,  Section IV, http://www.davidhume.org/texts/ehu.html, E4.9 )

One could be forgiven for thinking that this means that Hume was a sceptic about nature and natural laws themselves as real, and therefore sceptical about the basis of science in natural lawful nomic (law like or invariant) constraints. However, his scepticism is about our own epistemic access to nature: what we can possibly know about it with certainty. Hume's experiential data-gathering empiricism is exemplified clearly in the above passage in the first and second sentences. He thought empirical data was the only way of knowing anything (any matters of fact, or contingent facts in the world) reliably. However, Hume's scepticism about our ability to really know what is going on in nature and in causality troubles this empiricist view:
If we would satisfy ourselves, therefore, concerning the nature of that evidence, which assures us of matters of fact, we must enquire how we arrive at the knowledge of cause and effect. I shall venture to affirm, as a general proposition, which admits of no exception, that the knowledge of this relation is not, in any instance, attained by reasonings a priori; but arises entirely from experience, when we find, that any particular objects are constantly conjoined with each other. Let an object be presented to a man of ever so strong natural reason and abilities; if that object be entirely new to him, he will not be able, by the most accurate examination of its sensible qualities, to discover any of its causes or effects.(Hume, D. Enquiry Section IV, http://www.davidhume.org/texts/ehu.html, E 4.6, Emphasis Added)

I suggest that to regard Hume as a sceptic about science and nature rather than an empiricist first would be a misapprehension. However, as we will see later in this post and in Part II, Hume’s scepticism presents some difficult problems for his naturalism, and for realism about the external natural world (where external means existing outside of and apart from the mind and thought). For now, however, we can observe that, in all of his other philosophical musings, Hume tended to either emphasise or else openly rely upon the explanatory the role of nature (via empirical internal or mental experience), and to openly eschew supernaturalism and supernaturalist testimony (belief in the existence of supernatural entities and the ability to know any such thing) as constituting any kind of explanatory option.

Nature and Hume


The term ‘nature’ was at the time of Hume’s writings a philosophical term of art, and its real meaning and correct definition have been debated by philosophers from Aristotle to John Stuart Mill (who famously attempted a disambiguation and lamented the difficulties associated with its use in his 1874 ‘On Nature’). This is especially with respect to conceptions of human nature. 

In Hume’s moral theory - which has come to be known as moral sentimentalism because of the central role of human sentiment as a basis for moral values - common moral sentiments are determined in part by internal psychological similarities between human agents (although the term 'psychological' is anachronistic to his career and work). These psychological similarities are rooted in both human nature, nature in a broader sense, and in shared culture. It is precisely for these reasons, and because of Hume's rejection of the role of anything supernatural, that Hume’s theory of moral sentiments is an ethical naturalist theory 3.

In Chapter 10 of his famous 'Enquiry Concerning Human Understanding'  (titled 'Of Miracles'), Hume elevates natural material evidence in conjunction with careful step by step consideration of empirical information above human testimony, regarding the latter as all but useless in comparison as a basis for reliable knowledge. This applies especially where a testimony claimed supernatural/miraculous, or highly unusual events that would be remarkable by natural standards.

What Hume rejected, along with certain a priori knowledge about things such as cause and effect and the reliability of testimony of miracles, was the kind of a priori certainty that Rene Descartes sought to identify in his cogito. The Cogito is the name for Descartes’most famous idea – I think therefore I am/exist (which he never in fact stated in so many words). It is the idea that the only thing a person can know with certainty is that their thoughts exist. Descartes matched this posit with the idea that the Biblical God character (whom he thought actually existed) inspired and sustained a priori knowledge as well as sustaining mathematical truths. The foundation of all of these conclusions was Descartes' doctrine or principle of clear and distinct ideas: that if one could conceive of something as a clear and distinct idea, then that thing must be real. This is a form of a priori reasoning, or reasoning that does not require any experience of external (not mind or language dependent) past events and outcomes.

Recall that Hume rejected the value of a-priori reasoning pertaining to knowledge of facts about the world, and he emphasised the role of contradiction:

That there are no demonstrative arguments in the case, seems evident; since it implies no contradiction, that the course of nature may change, and that an object, seemingly like those which we have experienced, may be attended with different or contrary effects. May I not clearly and distinctly conceive, that a body, falling from the clouds, and which, in all other respects, resembles snow, has yet the taste of salt or feeling of fire? Is there any more intelligible proposition than to affirm, that all the trees will flourish in December and January, and decay in May and June? Now whatever is intelligible, and can be distinctly conceived, implies no contradiction, and can never be proved false by any demonstrative argument or abstract reasoning a-priori(Hume, D. Enquiry Section IV, http://www.davidhume.org/texts/ehu.html, E 4.18. Emphasis added.)
The term ‘demonstrative arguments’ in this passage refers to arguments from what does normally happen contingently in the world, rather than what somehow should happen according to a-priori reasoning just in our heads without any recording of outside events. Hume is being sceptical about our ability to be certain about natural laws, including constancy of cause and effect. He is saying that just because we have seen a certain outcome n times does not mean that we can be assured that the outcome will occur again the same way at the n+1 occurrence. This is even if it seems to be governed by natural lawful constraints and has always been totally consistent in the past. There is no demonstrative argument available that will prove the certainty of the outcome next time: no argument from reference to all or any of the past examples of a similar system, event, or situation.

In the above quotation, Hume intends his scepticism and empiricism to turn Descartes' conception of clear and distinct ideas - the foundation of The Cogito - against the conclusion that it is supposed to support. Descartes doubted everything about human perception and science, but not the certainty of awareness of and existence of one’s thoughts, which he took to be undeniably real for certain because of the intervention of a god being. Hume dispenses with even that certainty because of his sceptical empiricism, and with it the ability to know the god being if it exists. Overall, what Hume has to rely upon is a probable knowledge only. That is to say, we can know only that something is probable by empirical means:
 If we be, therefore, engaged by arguments to put trust in past experience, and make it the standard of our future judgment, these arguments must be probable only, or such as regard matter of fact and real existence, according to the division above mentioned. But that there is no argument of this kind, must appear, if our explication of that species of reasoning be admitted as solid and satisfactory. We have said, that all arguments concerning existence are founded on the relation of cause and effect; that our knowledge of that relation is derived entirely from experience; and that all our experimental conclusions proceed upon the supposition, that the future will be conformable to the past.  (Hume, D. Enquiry Section IV, http://www.davidhume.org/texts/ehu.html, E 4:19. Emphasis added.)
That supposition is, as I have described above, something that Hume asserts we must be sceptical about due to our ignorance. We don’t have a clue what really joins a cause to its effect, says Hume: we only know that one always comes after the other in proximity to it. For Hume, knowing things are probably the case or probably a fact is as good as it gets. His doubts about the reliability of the senses as a basis for gaining information from nature empirically (by past experience including repeated experiment) are not nearly as strict as those of Descartes, and his empiricism puts him at odds with Descartes about the value of empirically based science for gaining knowledge. Yet he rejects Descartes a-priori as unreliable, and and along with that Descartes’ Cogito becomes as only probable knowledge, and not certain:

It is only after a long course of uniform experiments in any kind, that we attain a firm reliance and security with regard to a particular event. Now where is that process of reasoning, which, from one instance, draws a conclusion, so different from that which it infers from a hundred instances, that are nowise different from that single one? This question I propose as much for the sake of information, as with an intention of raising difficulties. I cannot find, I cannot imagine any such reasoning. But I keep my mind still open to instruction, if any one will vouchsafe to bestow it on me.(Hume, D. Enquiry Section IV, http://www.davidhume.org/texts/ehu.html, E 4:20. Emphasis added.)

Hume relies on the regularity available through empirical observation, but only as probably predictive about future events. Hume's sceptical doctrine of causality is often taken to be not only about epistemic access - or our inability to get enough information about what will happen in a particular kind of system to predict what it will do in the future - but about actual unpredictability in physical systems. However, arguably, Hume's bite-the-bullet approach to causality - which saw him assert scepticism about empirical certainty in the constant regularity of causes and their effects - is not intended to undermine his empiricism.

Thus Hume is a sceptic and an empiricist. However, Hume’s scepticism causes him what is arguably a significant problem for his empiricism.

Rene Descartes
How, then, is empiricism and Hume's version of naturalistic scientism (a term anachronistic to Hume) prevail in the face of his scepticism about cause and effect, and his general scepticism? His empiricism relies on probable knowledge from experiment, which is far closer to scientific methodology and reasoning than is Descartes’Cogito.


As I have mentioned above, Hume rejects the thoroughgoing scepticism about the reliability of the senses that causes Descartes to reject experimental and materialist science as ineffectual. Descartes rejects the senses as reliable, and favours a-priori thought as the only way to know, and to know the god of the Bible, which character he took to exist. Descartes elevates a-priori reasoning - including that based upon mathematics and logic - as perfect and god-inspired. Materialist science, however, he regards as completely undermined by necessary doubts about the reliability of human senses as a way of knowing what is real in the world. According to Hume, however, sense impressions (which are in fact a complicated internal conception of the senses due to Hume’s scepticism) of empirical experiences are exactly where probable synthetic knowledge - the only kind available - must originate.
Descartes

Descartes was a devout theist and theologian, and when he referred to God he was making a reference in religious faith. Hume's numerous references to ‘God’, on the other hand, are famously deistic (he appoints no specific theological character to, nor claims a belief in the existence of any god being) and arguably tongue in cheek or else calculated to endorse critical thinking on the matter of how knowledge of the divine might be sustained. That or they are far more ambiguous in terms of ontological and doxastic (belief) commitments. Such references are arguably also fashioned after his unambiguous critical rejection of both religious enthusiasm and religious testimony.

Importantly, Hume intends his scepticism and empiricism to turn Descartes' conception of clear and distinct ideas - the foundation of The Cogito - against the conclusion that it is supposed to support: God exists because he can be conceived of as a clear and distinct idea and is therefore real. According to Hume, one can’t rely on human testimony about alleged miracles, and if there is any kind of god, you couldn’t possibly know such a being existed a-priori (and thus by faith).
 Whatever is may not be. No negation of a fact can involve a contradiction. The non-existence of any being, without exception, is as clear and distinct an idea as its existence...That the cube root of 64 is equal to the half of 10, is a false proposition, and can never be distinctly conceived. But that Caesar, or the angel Gabriel, or any being never existed, may be a false proposition, but still is perfectly conceivable, and implies no contradiction. (Hume, D. Enquiry Section XII Part 3, http://www.davidhume.org/texts/ehu.html, E 12.28)

This is the basis of what philosophers refer to as Hume's Fork. Hume regarded that there are two kinds of knowing: knowledge of the relations of ideas in a-priori reasoning, and knowledge of external mind-independent matters of fact in the world. The first kind of knowledge - a-priori analytic knowledge, is demonstrated in the above passage. It involves the identification of true and false statements on the basis of the presence or absence of contradiction: on a logical basis. The second kind of knowledge (see earlier quoted passage E 4:18 above) - called synthetic a-posteriori - requires experience of patterns and regularities in nature or in the external world.  

According to Cartesian a priori reasoning and the principle of clear and distinct ideas: it is every bit as likely that there is not any god being as that there is one. According to Hume there is no knowledge to be had in this - only in what has been empirically experienced through the senses - or more precisely - sense impressions.

It is these kinds of claims that were regarded as broadly heretical by the theologians of the time, and the same theologians and their allies troubled Hume’s career thereafter. In Part II we will explore the impact of Hume's scepticism on his naturalism and his theory of mind (there are serious problems for the senses and the existence of the external world), and the damage done to him by the religionist academy. 

1. Descartes, R. Meditations on First Philosophy, translated by John Cottingham, Cambridge: Cambridge University Press, 1996.

 ( See also The Philosophical Writings of Descartes, trans. John Cottingham, Robert Stoothoff, Dugald Murdoch and Anthony Kenny, Cambridge: Cambridge University Press, 3 vols. 1984-1991.)

2. Hume, D. An Enquiry concerning Human Understanding, edited by Tom L. Beauchamp, Oxford/New York: Oxford University Press, 1999. (See also <http://www.davidhume.org/texts/ehu.html>)

3. Hume, D. An Enquiry concerning the Principles of Morals, edited by Tom L. Beauchamp, Oxford/New York: Oxford University Press, 1998.

4. Hume, D. Treatise of Human Nature (Oxford, 1978), ed. L.A. Selby-Bigge and P.H. Nidditch.

5. Mill, J. S., Collected Works of John Stuart Mill, J. M. Robson (ed.), Toronto: University of Toronto Press, 1963ff.
POLLS:

Does information exist apart from perceiving agents (without some thinking organism to perceive it)?

Is Philosophy Relevant to Science?