Humean Causality and Presuppositionalism
David Hume’s Understanding of Causality
Back when I was explaining to Chris Bolt the importance of an objective
approach to induction, I pointed out one of David Hume’s key flaws in
formulating his skeptical conclusion about induction. Specifically, I explained
that Hume’s conception of causality as a relationship between “events,” as
opposed to a relationship between an entity and its own actions, is a
crucial premise in his infamous argument for skepticism in induction (see for
instance here
and here).
The reason for this should be simple to understand: on Hume’s conception, there
is no inherently necessary relationship which connects one event to
another which happens to follow it.
As Hume himself put it:
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. (An Enquiry Concerning Human
Understanding)
Hume’s conception of causality, as expressed here,
essentially guarantees a skeptical analysis of induction. (Hume made other
mistakes as well, and these simply doomed the Scottish thinker’s understanding
of induction all the more.) Since “all events seem entirely loose and
separate,” and causality is understood essentially as a succession of events
- one called cause, and the one whhich happens to follow it called effect
- it’s just a happy accident that touchinng the hot surface of a stove (the
“cause”) results in the experience of pain (the “effect”). On this view,
touching the hot surface of a backyard grill or molten iron could just as
easily result in pleasure, a musical performance, paper production, or anything
else, since they “seem… never connected.”
The implications which such a view of causality has for induction are hard to
miss. For instance, since on Hume’s view “all events seem entirely loose and
separate” and “we never can observe any tie between them,” a single instance of
one event following another is never sufficient to give us knowledge of a necessary
connection between two events such that we can be assured that they are
causally related (or “connected,” as Hume puts it). In other words, for Hume,
observing one instance of cause and effect is insufficient to validate what
some have come to call “the inductive principle,” that is, “the principle that
future unobserved instances will resemble past observed instances” (James
Anderson, Secular
Responses to the Problem of Induction; cf. also Brian Knapp, “Induction and
the Unbeliever,” The Portable Presuppositionalist,
pp. 121-122). Hume tells us this explicitly when he states:
When any natural object or event is
presented, it is impossible for us, by any sagacity or penetration, to
discover, or even conjecture, without experience, what event will result from
it, or to carry our foresight beyond that object which is immediately present
to the memory and senses. Even after one instance or experiment where we have
observed a particular event to follow upon another, we are not entitled to form
a general rule, or foretell what will happen in like cases; it being justly
esteemed an unpardonable temerity to judge of the whole course of nature from
one single experiment, however accurate or certain. (Op.
cit.)
Why is “one instance or experiment” not enough for
us “to form a general rule, or foretell what will happen
in like cases”? Because, according to Hume, “all events seem entirely loose and
separate” and, he says, “we can never observe any tie between them.” This seems
strange to me, as the pain that I experience when I touch a hot stove top does
seem very much “connected” to my touching the hot stove top in the first place.
But Hume says that “we never can observe any tie between” the one and the
other. Apparently we’re supposed to take his word for this.
But Hume doesn’t think we’re entirely lost on this. There is a way around this,
as he explains:
But when one particular species of event
has always, in all instances, been conjoined with another, we make no longer
any scruple of foretelling one upon the appearance of the other, and of
employing that reasoning, which can alone assure us of any matter of fact or
existence. (Ibid.)
So touching a hot stove top and experiencing pain only
once is not sufficient, says Hume, to draw the general inference that
touching it again will result in the same experience. But, he says, if this
happens “always, in all instances,” there is apparently no objection against considering
such a rule. In other words, in order to formulate the general rule that
touching a hot stove will cause pain, we need to know that in “all instances”
of touching a hot stove – that is, not 50%, not 75%, not 98% of the time, but
100% of the time – the one touching it experiences pain.
The question at this point becomes: how do we know when we have knowledge of
“all instances” of “one particular species of event”? Since we are not
omniscient, it can reasonably be supposed there will always be the possibility
that some instances of a particular species of event lie outside of our
knowledge, and among them may be instances which do not resemble the instances
which we do know about. Hume gives no indication as to how one could
confidently be assured that he has “all instances” to work with, or how one can
reliably conclude that there are no instances outside of his knowledge which
defy the norm of those which he does know. Since no one individual has
knowledge of “all instances” of touching a hot stove, Hume is essentially
saying that no one meets the minimum requirements needed to conclude as a
general rule that touching a hot stove will cause pain.
Hume’s own terms arbitrarily require omniscience as a standard, even though
there is no such thing as omniscience. But without it, his conception of
causality dooms us to the skepticism for which he is so famous.
To make matters worse, Hume seemed to believe that the imagination
serves as some kind of final court of appeal in settling the difficulty. In his
search for a “connexion” between one event (the
cause) and another (the effect), Hume explicitly pointed to what one “feels” in
his imagination, and only when repetition of the conjoined events in succession
is involved:
It appears, then,
that this idea of a necessary connexion among events
arises from a number of similar instances which occur of the constant
conjunction of these events; nor can that idea ever be suggested by any one of
these instances, surveyed in all possible lights and positions. But there is
nothing in a number of instances, different from every single instance, which
is supposed to be exactly similar; except only, that after a repetition of
similar instances, the mind is carried by habit, upon the appearance of one
event, to expect its usual attendant, and to believe that it will exist. This connexion, therefore, which we feel in the mind,
this customary transition of the imagination from one object to its usual
attendant, is the sentiment or impression from which we form the idea of power
or necessary connexion. Nothing farther is in the
case. Contemplate the subject on all sides; you will never find any other
origin of that idea. This is the sole difference between one instance, from
which we can never receive the idea of connexion, and
a number of similar instances, by which it is suggested. The first time a man
saw the communication of motion by impulse, as by the shock of two billiard
balls, he could not pronounce that the one event was connected: but only
that it was conjoined with the other. After he has observed several
instances of this nature, he then pronounces them to be connected. What
alteration has happened to give rise to this new idea of connexion?
Nothing but that he now feels these events to be connected in his
imagination, and can readily foretell the existence of one from the appearance
of the other. (Ibid.)
Essentially, Hume is saying here that, without a
sufficient number of iterations (Hume indicates no specific quantity here), the
imagination does not have enough input from the world to consider one event
“conjoined” with another, to be “connected” – i.e., to be causally
connected. If you touch your finger to a hot stove and feel
the pain of a burn one time, that’s not sufficient to attribute a causal
connection between the one action of touching your finger to a hot stove and
feeling pain. For Hume, you have to do this numerous times (how many, he does
not say) for you to finally “get it” (or “feel”) in your imagination
that touching a hot surface and experiencing pain are causally “connected.”
To make sure we understand this correctly, Hume states it again as follows:
In all single instances of the operation
of bodies or minds, there is nothing that produces any impression, nor
consequently suggest any idea of power or necessary connexion. But when many uniform instances appear, and the
same object is always followed by the same event; we then begin to entertain
the notion of cause and connexion. We then feel
a new sentiment or impression, to wit, a customary connexion
in the thought or imagination between object and its usual attendant; and this
sentiment is the original of that idea which we seek for. (Ibid.)
Streminger interprets Hume accordingly:
Since we never perceive a propter hoc,
but only a post hoc, causal connections have to depend on the creative
imagination. (Hume’s
Theory of Imagination)
Notice what is being affirmed here: that something
metaphysical (“causal connections”) depends on what the imagination creates.
The role of man’s imagination, says Streminger
(interpreting Hume), is “to structure the stream of [one’s] perceptions”
(Ibid.). Presumably, a “stream” of perceptions has no structure apart from what
the imagination imposes on them. Or, they do have a natural structure, but,
perhaps, the structure provided by the imagination has greater epistemological
import as a faculty by which those perceptions are assembled into content
amenable to inductive inference. Either way, the sequence here seems to be
perception plus imagination yields the material needed to generate inductive conclusions.
Causal connections in themselves are ultimately subjective phenomena on Hume’s
view. As John Vickers puts it, “the objectivity of causality,
the objective support of inductive inference, is thus an illusion” (The Problem of
Induction, from The Stanford
Encyclopedia of Philosophy).
In this way, I wager that David Kelley is correct in his assessment of Hume
when he interprets Hume to be saying (note that Kelley is not presenting the
Objectivist view here):
The mark of an axiom, of a self-evident
truth, is that we cannot deny it without contradicting ourselves. And the test
of whether a proposition is contradictory, is whether
we can imagine it. We cannot imagine a case where A equals not A. That’s why
the law of identity, A is A, is self-evident. It cannot be denied without
contradiction; we cannot imagine it being false. But we can imagine that fire
soothes on Monday, Wednesday and Friday, and burns on Tuesday, Thursday and
Friday, Sunday being a day of metaphysical rest. The law of causality can be
denied without self-contradiction, so it cannot be an axiom. And even if it
were an axiom, finally, that wouldn’t do us any good. Axioms, says Hume, are
merely relations among our own ideas. They are arbitrary constructs that we
make true by the way we define our own terms. And therefore they don’t tell us
anything about reality. (Universals
and Induction)
To be sure, Hume held some seriously defective
views. To summarize, Hume’s view of causality entails the following points:
1. Causality is a relationship between
“events”
2. There is no inherent necessity
connecting one event to another (they “seem entirely loose and separate” and
“we can never observe any tie between them”)
3. A single instance is never sufficient
to inform a general principle
4. Exhaustive knowledge of all instances
is needed to form a general principle (repetition)
5. The “necessity” of cause and effect
relationships is ultimately grounded in the imagination
Given underlying assumptions as strange as these,
it should be no wonder why Hume could only come to the conclusion about
induction for which he is so well known. Indeed, it could rightly be said that
the problem of induction is the problem of seeking an adequate justification
for inductive generalization when one’s conception of causality is so expressly
geared against it. Absent from Hume’s analysis, so far that I’ve been able to
find, is a defense of the view that causality is a relationship of events, or
of the premise that “all events seem entirely loose and separate” and that “we
can never observe any tie between them.” And yet, as should be clear, these are
key assumptions in Hume’s skeptical argument.
Hume and Presuppositionalism
Now it is important to
note that, when presuppositionalists raise the
problem of induction in their apologetic challenges against non-believers, they
very typically cite Hume as an authority on induction. And in doing so, they
express no concern for or dissatisfaction with Hume’s conception of causality
which underlies his skeptical conclusion about the nature of inductive
inference. On the contrary, presuppositionalists
generally point to Hume as if he were an unquestionable authority on the
matter. In this way presuppositionalists tacitly
endorse the premises in Hume’s argument, among them, sadly, his conception of
causality.
When engaging presuppositionalists who attempt to
raise the problem of induction as a debating point, it is a good idea to ask
them whether or not they think Hume’s argument for inductive skepticism is
sound. This will answer many questions at the outset. For instance, if the
apologist concedes that Hume’s argument is not sound, then he should
acknowledge the fact that raising the issue to begin with is futile. An
argument admitted to be unsound is not one which needs to be taken seriously. If
the apologist insists that Hume’s argument is sound, we should invite him to
reconstruct the argument and argue for its premises. Moreover, if he truly
thinks Hume’s argument is sound, then he needs to live with its skeptical
conclusion, and this would be counterproductive to his apologetic agenda.
In my experience, however, apologists who invoke the inductive version of presuppositionalism typically resist stating for the record
whether they think Hume’s argument is sound or not. (See for instance my 08
Oct. 2009 comment in this blog and my exchanges with Paul Manata in the comments section of this
blog.) This is quite telling, for it suggests that apologists who raise the
issue are unwilling to take much of a stand on it. It becomes all the more
revealing when it is pointed out that Hume’s conception of causality is faulty,
and apologists subsequently distance themselves even further from taking a
stand.
Swallowing Hume’s conclusion about induction in whole without examining
his premises seems to be commonplace among presuppositionalists,
even in the case of those who should know better. Greg Bahnsen,
for instance, who holds that “the causal principle is seen to be intelligible
only within the Christian framework of thought,” cites Hume as an “unbeliever”
who was “both brilliant and honest about the matter,” pointing to Hume’s
“devastating critique of causal reasoning in An Inquiry Concerning Human
Understanding” as “the foremost example of this” (Van Til’s Apologetic: Readings & Analysis, pp. 618-619,
including 619n.143). Hume is said by Bahnsen to number
among those “unbelievers” who “have openly conceded that they have no rational
basis for believing that the future will resemble the past” (Ibid., p. 619). Bahnsen summarizes the essence of the Humean
concession as follows:
We may have observed that event B followed
event A many times in the past, but to know that B necessarily follows A
(i.e., that the relation is causal), calls for reference to a metaphysical
principle (namely, the future will be like the past) for which the unbeliever
has no warrant or right. As Bertrand Russell was driven to conclude: “The
general principles of science, such as the believe in the reign of law, and the
belief that every event must have a cause, are as completely dependent upon the
inductive principle as are the beliefs of daily life. All such general
principles are believed because mankind have found
innumerable instances of their truth and no instances of their falsehood. But
this affords no evidence for their truth in the future, unless the inductive
principle is assumed.” Assumed? But that is what was supposed to be
proved! Russell was aware of his defeat: “Hence we can never use experience to
prove the inductive principle without begging the question. Thus we must… forgo
all justification of our expectations about the future.” (Ibid.;
quoting Russell’s “On Induction,” in The Problems of Philosophy (1912;
reprint, London: Oxford University Press, 1959), 69, 68.)
What is noteworthy here is that neither Bahnsen nor Russell ever seems to question Hume’s
conception of causality, an element which is integral to the skeptical
conclusion for which Hume is so famous.
Similarly, in his essay “Induction and the Unbeliever” (The Portable Presuppositionalist, pp. 118-142), presuppositional
apologist Brian Knapp cites Hume as one raising the question of how we can
justify induction (cf. pp. 122-123), but never questions the premises
underlying Hume’s argument for the view that “induction is hence unjustifiable”
(p. 129, citing this
Stanford Encyclopedia of Philosophy article). Nor does Knapp express any
concern for the particular understanding of causality assumed by Hume in
framing the famous problem.
So the tendency to miss the significance of Hume’s conception of causality in
generating his skeptical conclusion in regard to induction does not appear to
be an isolated incident, but rather a widespread habit. It is therefore
unlikely to occur to presuppositionalists that a
worldview which avoids the defects in Hume’s conception of causality may very
well be immune to the systemic skepticism to which it leads. Since Hume’s
conception of causality plays a central role in establishing his skeptical view
of induction, a philosophy which holds to an alternative understanding of
causality is unlikely to suffer from the same vulnerability.
In my paper Causality as a Necessary Relationship, I explain just how the
Objectivist view of causality does in fact avoid the pitfalls which plague
Hume’s problem of induction. However, it is my prediction that presuppositionalists will ignore these points as if they
did not pertain, and continue to insist that only Christianity somehow solves
the problem of induction (even though it lacks an objective understanding of
causality). But don’t be surprised when at this point they fail to present
arguments and instead prefer simply to rattle off questions in rapid succession
in the manner of “How do you know….?” over and over and over again, while
ignoring answers given to those questions.
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