Why Humans Believe What They Do Philosophy
The skeptical argument offered by David Hume, in his attempt to explain why humans believe what they do and as such whether or not they are in fact justified in believing such things, sets up the idea that knowledge comes in two forms; matters of fact and relations among ideas (Hume 193).
While knowledge concerning matters of fact is gained "a posteriori," through direct perception and experience, knowledge concerning relations among ideas is gained "a priori," independently from experience.
This knowledge of the external world, as argued by Hume, is neither produced inductively nor deductively and thus leaves us with no causal knowledge or knowledge of "matters of fact." I agree with the argument set forth by Hume in that we are not justified in believing conclusions of inductive inferences and will thus focus this paper on supporting this argument.
Hume suggests that causal relationships are part of two types of knowledge: relations of ideas and matters of fact.
As previously mentioned, relations of ideas are characterized as a priori knowledge, gained free of experience.
This type of knowledge is anything intuitively or demonstratively certain, such as mathematical, logical or conceptual truths (Hume 192).
For example, a mathematical truth such as, 2 + 5 = 7 is a relation of idea, as any sum other than 7 would be considered implausible.
In any attempt to falsify an a priori relation of idea, one is trapped in a contradiction.
Because of this contradiction, Hume immediately rejects a priori causal knowledge.
Thus, we will focus instead on the second type of knowledge concerning matters of fact.
Matters of fact consist of a posteriori knowledge, knowledge gained via experience (Hume 192).
As a matter of fact, Hume's example that the sun will rise tomorrow is based on our belief that causal relationships are based on past experiences.
Our confidence in the sun rising tomorrow lies in the fact that it has risen every day in the past.
Matters of fact develop from experience and are formed via a process of cause and effect (Hume 193).
Hume suggest that we learn this principle of cause and effect through experience and that most of our knowledge concerning facts depends on our knowledge of cause and effect.
Cause and effects are not discoverable through reason and without knowledge on cause and effect, we lack knowledge regarding matters of fact.
Hume lays out four conditions of causation so that event C causes event E if and only if:
C precedes E
C and E are close in spatial proximity
C type events are found to be "constantly conjoined" with E type events
C's occurrence makes E's occurrence necessary
However, according to Hume, there is no support for this cause and effect relationship.
Rather, he suggests that there is a practice in place of creating a relationship between two independent events out of habit.
Hume argues that effects and causes are two separate events and that the effect can not be discovered from the cause (Hume 195).
Drawing on the example of the billiard ball, we can see how this argument is valid.
Say that you have two billiard balls.
The first billiard ball moves in a direct path toward the second.
It is plausible to say that for any cause there is a limitless amount of effects that can arise.
While the second billiard ball in the past, once hit by the first, moved in a straight line, what is preventing the second billiard ball from remaining at rest or moving in another direction? As such, since there is no contradiction in assuming otherwise, we are unable to know that the future will mirror the past.
Hume argues that causal relations are found by induction, not reason since for any cause there are multiple effects.
Induction relies on the assumption that nature is consistent and that what happened in the past will mirror in the future.
However, as we have seen via the billiard ball example, this assumption is not justified.
We are now left to explain causal knowledge via a posteriori inductive reasoning.
There are two possible ways in which we can explain causal knowledge via inductive reasoning.
We could either directly perceive causal relations or infer inductively.
Referencing the above outlined conditions of causation, we are able to directly perceive the first three conditions but not the last.
Through the idea of "constant conjunction" we can see that event C (the cause) has generally occurred before event E (the effect).
Hume suggests that out of habit, when we see a constant conjunction our mind, though having no rational reason for doing so, creates a necessary connection between the two.
We connect these two propositions by induction rather than reason.
However, we can not rely on constant conjunction to explain causal relationships.
There appears not, throughout all nature, any one instance of connexion which is conceivable by us.
All events seem entirely loose or 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(Hume 211).
Induction uses what we learned from the past to conclude what will happen in the future.
In order for induction to be valid, however, there is the necessity to have a uniform principle in which it is secured that the future will be similar to the past (Hume 198).
Since a uniform principle is necessary to justify inductive claims, it itself is unable to be proved via induction and thus must be proved through experience.
Nevertheless, this leads to a circular pattern; cause and effect gives us knowledge through experience.
Induction explains cause and effect but induction itself relies on the fact that the future will resemble the past and his uniformity principle is known only through experience.
As such, without a uniformity principle that always holds true, there is no way to establish induction as a valid form of reasoning.
Maintaining that the sun will rise tomorrow is no more guaranteed than saying it will not (Hume 193).
Past experience leads to beliefs about the future which are not able to be rationally justified.
Though we are not able to rationally draw inductive inferences, we are subject to customs or habits formed throughout our minds experiences (Hume 200).
Humans typically hold that the future will bear a resemblance to the past in some way and support, as a matter of habit, a uniform principle.