David
Hume (1711-1776)
As was Locke and Berkeley, David Hume
was an Empiricist. However, there is a
sense in which he does to Berkeley what Berkeley did to Locke. While Berkeley accuses Locke of not being
true to the tenants of empiricism when Locke posits physical substance, Hume
claims Berkeley is guilty of the same thing when Berkeley posits mental
substance. We never perceive “mental
substance” according to Hume. We never
perceive “mind” Hume asserts, not even our own.
·
Berkeley doesn't
take empiricism far enough.
·
Hume accuses
Berkeley of illicitly positing “mental substance”/ minds
o
Do I ever experience my mind? Do I
ever experience mental
substance? No. says Hume
When one looks inward for one’s own
“mind” all one finds is a “bundle of impressions” (experiences)
David Hume, A Treatise of Human Nature: BOOK I OF THE UNDERSTANDING,
PART IV. OF THE SCEPTICAL AND OTHER SYSTEMS OF PHILOSOPHY, SECT. VI. OF
PERSONAL IDENTITY.[1]
1 There are some philosophers who imagine we are every moment
intimately conscious of what we call our SELF; that we feel its existence and
its continuance in existence; and are certain, beyond the evidence of a
demonstration, both of its perfect identity and simplicity. The strongest
sensation, the most violent passion, say they, instead of distracting us from
this view, only fix it the more intensely, and make us consider their influence
on self either by their pain or pleasure. To attempt a farther proof of this
were to weaken its evidence; since no proof can be derived from any fact, of
which we are so intimately conscious; nor is there any thing, of which we can
be certain, if we doubt of this.
Unluckily all these positive assertions are contrary to that
very experience, which is pleaded for them, nor have we any idea of self, after
the manner it is here explained. For from what impression could this idea be
derived? This question it is impossible to answer without a manifest
contradiction and absurdity; and yet it is a question, which must necessarily
be answered, if we would have the idea of self pass for clear and intelligible. [2]
It must be some one impression, that gives rise to every real idea.[3]
But self or person is not any one impression, but that to which our several
impressions and ideas are supposed to have a reference. If any impression gives
rise to the idea of self, that impression must continue invariably the same,
through the whole course of our lives; since self is
supposed to exist after 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 self is derived;
and consequently there is no such idea.
But farther, what must become of all our particular
perceptions upon this hypothesis? All these are different, and
distinguishable, and separable from each other, and may be separately
considered, and may exist separately, and have no Deed of tiny thing to support
their existence. After what manner, therefore, do they belong to self; and how
are they connected with it? For my part, when I enter most intimately into what
I call myself, I always stumble on some particular perception
or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I
never can catch myself at any time without a perception, and never can observe
any thing but the perception. When my perceptions are removed for any time, as
by sound sleep; so long am I insensible of myself, and
may truly be said not to exist. And were all my perceptions removed by death,
and could I neither think, nor feel, nor see, nor love, nor hate after the
dissolution of my body, I should be entirely annihilated,
nor do I conceive what is farther requisite to make me a perfect non-entity. If
any one, upon serious and unprejudiced reflection
thinks he has a different notion of himself, I must confess I can reason no
longer with him. All I can allow him is, that he may be in the right as well as
I, and that we are essentially different in this particular.
He may, perhaps, perceive something simple and continued, which he calls
himself; though I am certain there is no such principle in me.
But setting aside some metaphysicians of this kind, I may venture
to affirm of the rest of mankind, that they are nothing but a bundle
or collection of different perceptions, which succeed each other with
an inconceivable rapidity, and are in a perpetual flux and movement. Our eyes
cannot turn in their sockets without varying our perceptions. Our thought is
still more variable than our sight; and all our other senses and faculties
contribute to this change; nor is there any single power of the soul, which
remains unalterably the same, perhaps for one moment. The mind is a kind of
theatre, where several perceptions successively make their appearance; pass,
re-pass, glide away, and mingle in an infinite variety of postures and
situations. There is properly no simplicity in it at one time, nor identity in
different; whatever natural propension we may have to imagine that simplicity
and identity.[4]
The comparison of the theatre must not mislead us. They are the successive
perceptions only, that constitute the mind; nor have we the most distant notion
of the place, where these scenes are represented, or of the materials, of which
it is composed.
What then gives us so great a propension to ascribe an identity
to these successive perceptions, and to suppose ourselves possest of an
invariable and uninterrupted existence through the whole course of our lives?
In order to answer this question, we must distinguish betwixt personal
identity, as it regards our thought or imagination, and as it regards our
passions or the concern we take in ourselves. The
first is our present subject; and to explain it perfectly we must take the
matter pretty deep, and account for that identity,
which we attribute to plants and animals; there being a great analogy betwixt
it, and the identity of a self or person.[5]
Note:
Very close to saying there is no "me;" only a current of experiences;
mind is a cascade of impressions; there is no enduring Ego; there is no single
mind; Hume is denying the reality of( or at least claiming there is no
empirical grounds for positing ) the self.
Curiously, this is similar to the Buddhist or
Zen Buddhist view with which he was probably unfamiliar[6]; he
denies a Cartesian ego (that you exist, that you are a thinking thing).
Alfred North Whitehead (1861 – 1947) makes
a similar point in his book Process and Reality.
“In
the quotation from the second Meditation: ‘I am, I exist, is necessarily true
each time that I pronounce it, or that I mentally conceive it.’ Descartes
adopts the position that an act of experience is the primary type of actual
occasion. But in his subsequent developments he assumes that his mental
substances endure change. Here he goes beyond his argument. For each
time he pronounces 'I am, I exist,' the actual occasion, which is the ego, is
different;” (pg 75)
“It must be some one impression that gives rise to every real
idea. But self or person is not any one impression, but that to which our
several impressions and ideas are supposed to have a reference. If any
impression gives rise to the idea of self, that impression must continue
invariably the same through the whole course of our lives, since self is
supposed to exist after 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 self is derived,
and, consequently, there is no such idea.”[7]
For Hume, we can only claim that there
are “phenomena” on empirical grounds.
Phenomenalism ‑ the view that the only things which exists are
experiences or impressions or phenomena; (no physical substance; no mental
substance)
3 Metaphysical Positions:
1. Substance Dualism: There are two kinds
of distinct substances - usually mental and physical.
2. Substance Monism: There is only one
substance.
2a.
Monist Materialism/ Physicalism,
there is only one substance and it is material in
nature.
2b. Monist Idealism- there is only one substance and it is mental in nature. (e.g. Berkeley’s theory that the only things which
exist are ideas and the minds that perceive them.)
3. Phenomenalism: The only things which
exists (or at least the only things which we are justified in asserting exist)
are phenomena - metal sensations.
Hume is taking empiricism to its
logical conclusion. If our only source
of knowledge is our own impressions, then the only things that we can say we
know to exist are our own impressions.
Hume’s Epistemology
Hume insists, in a manner similar to Locke, that all knowledge begins with basic units
of sensory experience[8]. Simple "impressions" lead to simple
ideas which in turn can be built up into more complex ideas. Seeing a red round patch, (impressions) leads
to an idea red round object (simple idea) which, together with other simple
ideas (solid object, tart object, sweet object ) lead the idea of an apple(a complex
idea).
Hume distinguishes
between ideas and impressions.
“All the perceptions of the human mind
resolve themselves into two distinct kinds, which I shall call impressions and
ideas. The difference betwixt these consists in the degrees of force and
liveliness with which they strike upon the mind, and
make their way into our thought or consciousness. Those perceptions, which
enter with most force and violence, we may name impressions; and under this
name I comprehend all our sensations, passions and
emotions, as they make their first appearance in the soul. By ideas I mean the
faint images of these in thinking and reasoning; such
as, for instance, are all the perceptions excited by the present discourse,
excepting only, those which arise from the sight and touch, and excepting the
immediate pleasure or uneasiness it may occasion.[9]
According to Hume, simple ideas are derived from simple
impressions. A simple impression would be a sensation of seeing a
red, round image. A simple idea would be
something like the idea of red. More
complex ideas, for example, the idea of an apple, are complex arrangements and
associations of simple ideas. [10]
To justify a belief as knowledge, therefore, we must
break up its complex ideas into simple ideas and then find the impressions upon
which those ideas are based.
Complex idea -> Simple Idea -> Simple
Impression[11]
Any ‘IDEA’ for
which we could not provide this kind of analysis was illegitimate and
inconsistent with the tenets of empiricism.
If I claim to see
an apple, for example, I analyze my experience; my idea that there is an apple “out
there” depends upon my seeing several red, round images from different angles,
feeling something smooth, tasting something fruity and tart, and so on.
If I claim that
there are objects of a certain kind (apples, for example), I must identify the
simple ideas and impressions upon which my supposed knowledge is based. Likewise, if I make a metaphysical claim,
about the existence of God or substances, I must either be preapproved to
identify the ideas and impressions upon which such a claim is based as a matter
of fact, or I must show that it is nothing other than a conceptual truth (a "relation
of ideas"). Otherwise, the claim
cannot be justified (i.e. "commit it to the
flames").
Hume's Fork
So for Hume there really are only two
ways to justify a belief:
I. relation of ideas
II. matters of fact
I. relation of ideas
·
a priori
·
definitional
·
analytic (A=A)
·
non-augmentative
·
Ex: All sisters are siblings.
Most are trivial but also math and geometry
II. matters of fact
·
Empirical
·
synthetic (A=B)
·
augmentative
·
Ex: All swans are white. (Only way to
justify out is to go out and look.)
This covers, roughly, scientific claims.
According to Hume these are the only ways to justify a belief.
"When
we run over our libraries, persuaded of these principles, what havoc must we
make? If we take in our hand any volume; of divinity or school metaphysics, for
instance; let us ask, Does it contain any abstract
reasoning concerning quantity or number? No. Does it contain any experimental
reasoning concerning matter of fact and existence? No. Commit it then to the
flames: for it can contain nothing but sophistry and illusion."[12]
This is a full-frontal attack on
traditional metaphysics. If every justifiable
belief must be either a "relation of ideas," or a "matter of
fact" then it seems impossible to justify metaphysical claims which are
neither. Many rationalist
modern philosophers have a broader conception of what can be known by appeal to
“reason” than did Hume.[13] But if we agree with Hume that a priori claims amount only to those
which reduce to logical tautologies (and math perhaps) [14]
then so much the worse for metaphysics, and a good deal of traditional
philosophy as well. They are, by their
very nature, about things beyond everyday experience (for example, God,
substance. Etc.) and so are not based upon any "impressions.“ Metaphysical
concepts, it would seem, in no way can be traced back to simple ideas or
impressions. Nor are they
"relations of ideas" that can be demonstrated by a purely logical or
mathematical proof.
Hume singles out three
such metaphysical beliefs in particular for analysis:
These three basic beliefs are intimately
tied together; the notion of cause supports the principle of induction
and the principle of induction supports the notion of causation. Further, the theory of causes supports the causal
theory of perception (Our perceptions don’t just happen for no reason at
all.) which in turn supports our belief
in the "external world" as the supposed source of our
perceptions.
Hume on Causation:
First Hume examines our idea of
causation (or causality), that is, of one event “bringing about” or causing/
necessitating another event. This idea,
which provides what Hume calls "the strongest connections" of our
experience and, elsewhere, "the cement of the universe," we derive a
most important principle: the principle of universal causation. This states that every event has its cause
(or causes).
It is evident that we invoke such a
principle every time we explain anything; for example, the car won't start. We search for the cause, but everything seems
to check out the- carburetor, the
electrical system, and so on. Now we
might search for hours without finding the cause, but there is one thing that
we know for certain and that is that there must be a cause somewhere-even if it
is a very complex cause. What we would
NOT accept, we would deem as not possible is that there be NO cause.
Presupposed in our everyday thinking is this principle, that every event has
its cause. (You may recognize this
principle as a version of the Principle of Sufficient Reason, which substitutes
the more Newtonian notion of "cause" for the notion of
"reason.")
Note: if your mechanic told you that there was in fact
nothing wrong with your car and that there was simply no cause for the fact
that it will not start, you would seek out a different mechanic, one who did
subscribe to the principle of universal causation. (Likewise with your doctor, psychologist,
architect, scientist, etc.)
Second, it is because of this
confidence in causation and its universal applicability that we think ourselves
justified in drawing conclusions about what is beyond our immediate
"ideas." (i.e. to predict future experiences
and explain the past one). Hume asks how
it is that we can go from observing something a finite number of times to predicting
that it will occur an infinite number of times.
(e.g., the rate of free falling is 32ft/s/s) Hume asks what makes us
trust these inferences. What makes us
believe that past experience is a reliable guide to
predicting future experience?
But the claim of universal causation
cannot be an a priori “relation of
ideas,” says Hume.
“We
can never demonstrate the necessity of a cause to every new existence, or new
modification of existence, without shewing at the same time the impossibility
… that any thing can ever begin to exist without some productive principle;
Recall that Hume believed that the only
things that could be proven necessarily true are those claims, the negation of
which implies a contradiction.
“…
and where the latter proposition cannot be proved, we must despair of ever
being able to prove the former.”
Since there seems to be no logical
contradiction in the idea of an uncaused thing or an uncaused event, we cannot
know that every event has a cause a
priori.
“Now
that the latter proposition is utterly incapable of a demonstrative proof, we
may satisfy ourselves by considering that as all distinct ideas are separable
from each other, and as the ideas of cause and effect are evidently distinct,
it will be easy for us to conceive any object to be non-existent this moment,
and existent the next, without conjoining to it the distinct idea of a cause or
productive principle. The separation,
therefore, of the idea of a cause from that of a beginning of existence, is
plainly possible for the imagination; and consequently
the actual separation of these objects is so far possible, that it implies no
contradiction nor absurdity; and is therefore incapable of being refuted by any
reasoning from mere ideas; without which it is impossible to demonstrate the
necessity of a cause.[15]
So might our belief in causation and
causes be grounded in experience (a “matter of fact”) then?
Perhaps not. Note that what is given in experience is merely
a finite set if instances of a constant conjunction of two events, according to
Hume. B has always preceded by A when
observed. We therefore conclude A necessitates/
causes B. But on its own, this is surely
unjustified. What we observe is constant
conjunction that for all we know is accidental, but what we assert is a
necessary connection. The repeated
observations can explain the psychological expectation of B when
we witness an A (Think Pavlov’s dog.), but the claim that there is a “necessary
connection” is an unwarranted inference were it based
on the constant conjunction alone.
“All events seem entirely loose and separate. One event follows
another; but we never can observe any tie between them. They seem conjoined,
but never connected. And as we can have no idea of any thing which never
appeared to our outward sense or inward sentiment, the necessary conclusion
seems to be that we have no idea of connexion or power at all, and that these
words are absolutely, without any meaning, when employed either in
philosophical reasonings or common life.”[16]
Hume is pointing out that there is no simple
sensation that appertains to the “idea” of cause. If there were, if we could know that A causes
B merely by observation, indeed the very first time we observed A and then B; we
would “see” that one event causes another the very first time we witness the
two if it were there to be seen at all. But
we do NOT know/see that A causes B the first time. But then neither do we the second or third or
fourth or so on.
If this is so, causation is not given in direct
experiences. Where does it come
from then?
All we get in perception is “constant
conjunction.” We have always experiences A followed by B in the past and we have never
experienced a B without a preceding A.
But this is insufficient to establish a necessary
connection, a key component in the concept of “causation,” between A and B. Therefore, we must look for the ground of
“causation” elsewhere. To do so, we must also believe that our observations of
the present will have some relevance in the future, that we can in fact draw
valid inductive generalizations from our past experience.
Hume asks
“What justifies this mental move?”
Answer…
Principle of Induction:
The only thing that could is the
“Principle of Induction.” It is the
unstated premise in all inductive arguments.
This is what makes us believe that past experience
is a reliable guide to predicting future experience. We believe that the future will be like the
past, at least in broad outline. We believe that the universe works by laws
which will not/cannot change and therefore patterns of behavior long witnessed
will continue into the future indefinitely.
Thus, induction takes on this
character:
A had always been
followed by B in the past.
The future will be
like the past.
Therefore:
A will be followed
by B today.
Thus it is the Principle of Induction that
gives us confidence in making claims about causation (A necessitates B) and
belief/expectations about the future. Beliefs about causes or the future all
depend on the principle of induction.
Imagine I told you that at 5:00 PM today, all the laws of physics would
cease to hold, and indeed would be replaced by new ones. If this were so, you could not tell me what
the world would look like at 5:01 PM.
For all we know, arsenic might stop being poisonous and bread stop being
nourishing.[17]
Turns on Three Concepts:
1. Traditional Account of Knowledge
2. Hume’s Fork
3. Principle of Induction
1.
Traditional Account of Knowledge (goes back to Plato) ‑ trying to
understand what one is saying when one claims that some subject “S” knows some
proposition “P.”
S knows that "P" =
S
believes "P"
P
is true
S
is
justified in her belief that "P"
Thus: K= TJB (Knowledge = true, justified, belief)
Highlights the importance justification
as necessary for any truthful ascriptions of knowledge.
Hume accepts this.
Thus, the crucial epistemological
becomes, “What is justification?” “What
are the ways we can justify beliefs?”
2.
Hume's Fork
Hume says there are only two ways to
justify beliefs. (see above)
I. relation of ideas
II. matters of fact
3.
The Principle of Induction: The Future will be like the past.
Putting it all
together:
·
To be justified a
belief must be either a relation of ideas or a matter of fact. (Hume’s fork)
·
The principle of induction is not a
relation of ideas.
o
(Not mere definition, non-augmentative
knowable a priori)
·
The principle of induction is NOT A matter
of fact.
o
(Not empirical because we cannot
observe the future.)
Therefore
·
The principle of induction cannot be
justified.
Therefore
·
Nothing that relies on the POI for
justification can be justified.
·
All inductive
beliefs ultimately rely on the principle of induction (i.e.
The future will be like the past.)
Therefore
·
One can never be said to have a justified
belief about the future or the causes of things.
Therefore
·
One can never be said to have knowledge about
the future or the causes of things.
Put
more simply:
To know something,
one must have justification. (Traditional Account of Knowledge)
One cannot get
justification for the principle of induction. (Hume’s Fork)
One cannot know
the principle of induction. (Problem of Induction)
Since the principle of induction is
itself unjustified, it cannot provide justification for any other beliefs. Therefore, no beliefs which depend on the
principle of induction are justified nor can they be known (science,
claims about the future, causality, etc.)
Hume is a skeptic with regard to claims about
the future or causality.
Skeptic – One who claims that knowledge is
impossible.
Hume attempts to refute both the
principle of universal causation and the principle of induction by showing that
neither is a "relation of ideas," nor "matter of fact." Since any statement of human knowledge requires
justification (Kn =TJB), and justification comes in one of only to forms
(Hume’s Fork RoI and MoF), any statement
of human knowledge must be one or the other.
But neither the principle of
induction nor the principle of causation is either so
neither can be said to be known. Note,
for Hume they might very well be TRUE, but true belief is not
sufficient for knowledge. According to
Hume, neither is justified and thus neither is known. We have absolutely no reason to believe
either nor do we have reason to believe any belief that rests upon either (e.g. that arsenic will poison me – causation- nor that the
sun will rise tomorrow).
Possible solutions? Well one might
claim that Hume’s Fork is missing a tine.
That is, one might claim that THERE is a third means of justifying a
belief other than the two that Hume offers.
(One might consider Immanuel Kant or William James
here.)
The “External” World
The third of our common-sense beliefs
Hume calls into question is the belief in an "external world," that
is, a physical or material world which exists independently of our impressions
and ideas, and which is the cause of these impressions. Bishop Berkeley had already done Hume's work
for him here. Hume, following Berkeley, also rejects all notions of substance
as unintelligible, including even that minimal "something we know not
what" of John Locke.
But where Berkeley turned the rejection
of Locke’s notion of matter and physical substance into a rejection of Locke’s metaphysical
dualism in preferences to his own
idealism (namely, his Subjective Idealism) and used it to defend the existence
of God, Hume rejects this idealist metaphysics as well and remains wholly
skeptical, refusing to accept the existence of God. Hume remains firm in his insistence that our
belief in the existence of anything is no different from "the idea of what
we conceive to be existent."
We can see that these three basic
beliefs are intimately tied together; the principle of induction supports the
principle of universal causation, and the causal theory of perception supports
our belief in the "external world."
Hume asserts that all human knowledge
must be either a "relations of ideas" or
"matters of fact," then shows that "cause and effect" and
“induction” are the basis of all reasoning about the world, and then proceeds
to show that such reasoning can be neither a relation of ideas nor a simple
matter of fact.
It may, therefore, be a subject worthy of curiosity, to enquire
what is the nature of that evidence which assures us of any real existence and
matter of fact, beyond the present testimony of our senses, or the records of
our memory. This part of philosophy, it is observable, has been little
cultivated, either by the ancients or moderns; and therefore
our doubts and errors, in the prosecution of so important an enquiry, may be
the more excusable; while we march through such difficult paths without any
guide or direction. They may even prove useful, by exciting curiosity, and
destroying that implicit faith and security, which is the bane of all reasoning
and free enquiry. The discovery of defects in the common philosophy, if
any such there be, will not, I presume, be a discouragement, but rather an
incitement, as is usual, to attempt something more full and
satisfactory than has yet been proposed to the public.[18]
As we shall see, Immanuel Kant will
take up precisely this challenge.
Hume famously writes in his first book,
the A Treatise of Human Nature:
Most fortunately it happens that, since reason is incapable of
dispelling these clouds, nature herself suffices to that purpose, and cures me
of this philosophical melancholy and delirium, either by relaxing this bent of
mind, or by some avocation and lively impression of my senses which obliterate
all these chimeras. I dine, I play a
game of back-gammon, I converse and I am merry with my
friends; and when after three or four hours' amusement, I would return to these
speculations, they appear so cold and strain'd, and ridiculous, that I cannot
find in my heart to enter into them any further. [19]
[2] Hume is referencing Rene Descartes here, I think. The Cogito Ego Sum by which Descartes concluded that he is essentially a “mental substance,” that is, an enduring mental “ego” which persists over time and changes, the reality of which is indubitable.
[3] Here, Hume is taking himself to be a good empiricist to say if the “idea” of a “self” is to have any empirical validity, it must be traced back to some “sense impression.” But he can find no sense impression which provides the content/substance for the “idea” of a self.
[4] Note, he is saying that the phenomenology of introspection does not reveal and enduring entity but rather a successive parade of sensations. There is, therefore, no (empirical) reason to suppose there exists anything further than this “bundle of impressions.” if empiricism is correct and Hume is correct here then this only justifies phenomenalism and justifies neither “materialism,” “dualism” nor even “idealism.”
[5] He seems here to be saying that our propensity to ascribe an enduring identity to ourselves is a transference of our tendency to ascribe an enduring identity to external objects, such as plants and animals etc. These, no more than ourselves, might be nothing more than a series of sequential experiential impressions or phenomena which we, unjustifiably, regard as enduring permanences. Curiously, he is anticipating the event ontologies of individuals such as Alfred N Whitehead.
[6] It is a current matter or debate in Hume scholarship as to whether or not Hume had any familiarity with Buddhist thought.
[7] Treatise I.4.6, AW 526a
[8] This epistemological view has also been termed “Sensationalism.”
[9] Note here that Hume is suggesting the only difference between “impressions” and “ideas” are phenomenological distinctions. The first are irresistible to a certain extent and come to the mind “unbidden.” The others are fainter and more subject to voluntary manipulation. This is in contradistinction to those who would that the former are somehow related / caused by to an “objective mind independent world” while the latter are not.
[10] It is noteworthy that Hume identifies what he take to be the simple sensation that distinguishes a memory from a perception, namely the “degree of force” or “liveliness” of the impression.
[11] Ironically Hume provides his own counter-example for this view. He invites us to imagine someone presented with a spectrum of shades of blue, each differing from its neighbor to a predictable degree. If one shade were missing, then, using his or her imagination, that person would be able to form an idea of that shade despite not being presented with the corresponding simple sensation. But, then Hume dismisses the example as unimportant. (Hume, Enquiries, Section II. Of the Origin of Ideas)
[12] ^Hume, D., Inquiries concerning Human Understanding and concerning the Principles of Morals Reprinted from 1777 edition, Third Edition, L. A. Selby-Bigge (ed.), Clarendon Press, Oxford, Sect. XII, Part III, p.165.
[13] For instance, Leibnitz would maintain that “The Principle of Sufficient Reason” and other metaphysical claims are known by rational intuition.
[14] Recall that the only things that can be proven a priori according to Hume are those claims, the negation of which involves a logical contradiction. This was his objection to Anselm’s ontological argument for the existence of God.
[15] Hume A Treatise on Human Nature, Book I, Part III, Section III
[16] David Hume (1711–76). An Enquiry Concerning Human Understanding. The Harvard Classics. 1909–14. Of the Idea of necessary Connexion Part II
[17] See: https://www.youtube.com/watch?v=0_ckzZWDth8&t=101s (Interesting recent video pertinent to this lecture.)
[18] David Hume. An Enquiry Concerning Human Understanding. 2nd ed .• ed. l. A. Selby'Bigge. Oxford: Oxford University Press. 1902.
[19] David Hume (1711–76) A Treatise of Human Nature, Book I, Part IV, Section VII, p. 269 in the Selby-Bigge edition