Hume first explains the principle of evidence: the only way that we can
judge between two empirical claims is by weighing the evidence. The
degree to which we believe one claim over another is proportional to
the degree by which the evidence for one outweighs the evidence for
the other. The weight of evidence is a function of such factors as the
reliability, manner, and number of witnesses.
Now, a miracle is defined as: "a transgression of a law of nature by a
particular volition of the Deity, or by the interposition of some invisible
agent." As the evidence for a miracle is always limited, as miracles are
single events, occurring at particular times and places, the evidence
for the miracle will always be outweighed by the evidence against
the evidence for the law of which the miracle is supposed to be a
Empiricism - the theory that all knowledge is derived from sense-
experience. For Hume, all the materials of thinking perceptions
are derived either from sensation (outward sentiment) or from
reflection (inward sentiment) Trying to go beyond perceptions, as
metaphysics must, inevitably involves going beyond anything that can
have cognitive content.
Deflationism - According to the deflationary theory of truth, to assert
that a statement is true is just to assert the statement itself. For
example, to say that snow is white is true, or that it is true that snow
is white, is equivalent to saying simply that snow is white, and this,
according to the deflationary theory, is all that can be said significantly
about the truth of snow is white.
Copy Principle - Hume presents the Copy Principle as an empirical thesis. The Copy Principle accounts for the origins of our ideas. The
principles required for connecting our ideas aren't theoretical and
rational; they are natural operations of the mind that we experience in
internal sensation. Hume identifies three principles of connexion or
association: resemblance, contiguity, and cause and effect.
Missing Shade of Blue - the infamous missing shade of blue as an
empirical counterexample to the Copy Principle. Hume plausibly
maintains that we would first notice that there is a gap where the
shade is missing from our mental ordering of the shades of blue, just
as we would also easily notice when a chip was missing from the
Hume accepts that the object of knowledge is solely the sense
impressions perceived by the subject. The impression is an actual vivid
perception which brings with it conviction or positive belief in the
existence of a corresponding objective reality. Hume logically
developed to its extreme conclusions the empiristic principle that
subjective impressions alone are the immediate objects of knowledge.
Passage outside our sensitive impressions is not possible. Hence there
is no metaphysics: we know nothing of God, of the exterior world, or of
our own soul.
Simple v. complex idea
For Hume, simple ideas are faint copies of impressions, whereas
complex ideas are ensembles or assemblages of simple ideas. First,
every simple idea is a copy of an impression of inner or outer sense.
Second, every complex idea is a bundle or assemblage of simple ideas,
i.e., complex ideas are structured ensembles of simple ideas. The Problem of Induction
Induction is: a means of proving a theorem by showing that if it is true
of any particular case, it is true of the next case in a series, and then
showing that it is indeed true in one particular case. Hume believes
that induction cannot be justified. Since induction is a contingent
methodeven good inductions may lead from truths to falsehoods
there can be no deductive justification for induction. First, Hume
ponders the discovery of causal relations, which form the basis for
what he refers to as "matters of fact." He argues that causal relations
are found not by reason, but by induction. This is because for any
cause, multiple effects are conceivable, and the actual effect cannot
be determined by reasoning about the cause; instead, one must
observe occurrences of the causal relation to discover that it holds.
Hume ponders the justification of induction. If all matters of fact are
based on causal relations, and all causal relations are found by
induction, then induction must be shown to be valid somehow. He uses
the fact that induction assumes a valid connection between the
proposition "I have found that such an object has always been
attended with such an effect" and the proposition "I foresee that other
objects which are in appearance similar will be attended with similar
effects." How do human beings form opinions about unobserved
matters fact? In this way, the problem of induction is not only
concerned with the uncertainty of conclusions derived by induction,
but doubts the very principle through which those uncertain
conclusions are derived.
In David Hume's system, impressions and ideas are the substances.
According to Hume, our belief in substance is the result of a mistake or
illusion. Thus Hume's treatment of substance is like his treatment of
causation, in that he sees both as the projection onto the world of a tendency of our minds either to pass from one thing to another or to
associate them in some way.
Hume - who held that the self is nothing but a bundle of interconnected
perceptions linked by relations of similarity and causality; or, more
accurately, that our idea of the self is just the idea of such a bundle.
There is a relationship between cause and effect and the principle that
everything has a cause. In other words, if we believe a relationship
exists between two events, then one of these events, the cause, will
readily recall the other, the effect. The problem comes, of course,
when we ask how it is that we know that a causal relationship exists.
Obviously, a distinction must be made between causation as a physical
property and causality as a mental idea. Traditionally, the following
definitions have been made: causation is the physical property of one
event causing another, such as one ball colliding with and causing the
movement of a second ball. This property is part of the realm of
mechanics and physics. Causality, on the other hand, describes the
attribution by an organism of an effect to a cause.
- an absence for constraint.
In Hume we see the final logical consequences which an empirical
theory of knowledge entails. The result is skepticism. We have no
certain, self-evident knowledge of anything. Our knowledge is confined
to impressions and ideas, and so we are not in a position to assert the
existence either of material objects or of spiritual entities. Our notion
of causality, that a particular effect is necessarily produced by a