1. An Enquiry Concerning Human Understanding
Philosophy 1
Spring, 2002
G. J. Mattey

2. British Empiricism
John Locke ( ) adopted Descartes’s “new way of ideas”
Locke rejected innate ideas, claiming that all ideas come from experience
He also held that all that can be known on this basis is our own existence, the existence of God, and that of material things we are now sensing
George Berkeley ( ) denied the existence of matter altogether

3. David Hume Born 1711 Scottish Historian of England Popular essayist
Worked in diplomacy
Denied teaching position due to charges of atheism
Died 1776

4. Hume’s Contributions
Argued for moderate skepticism in theoretical matters
Cause and effect
Personal identity
Existence and nature of God
Tried to base geometry on sensory experience
Originated the “belief-desire” account of human action
Proposed an ethical theory based on the feeling of sympathy

5. Species of Philosophy
There have been two prevailing species of philosophy
A popular philosophy, which is easy to comprehend and which motivates people to act virtuously
An abstruse philosophy, which is difficult and which seeks to understand the principles governing human nature

6. Reason and Action
Profound research is thought to be useless, and it produces uncertainty that leads to melancholy and rejection
It cannot be sustained in a social setting
Merely acting, while ignorant, is despised
The mind needs rest from constant activity
The best life is a mixed one
“Be a philosopher, but, amid all your philosophy, be still a man”

7. Metaphysics Metaphysics is accurate and abstract
Accuracy is advantageous to art, business, government, law, etc.
The study of metaphysics is pleasurable to those with vigorous minds
But its obscurity harbors error by giving shelter to superstition
This is why metaphysics must be pursued, yet in an “easy” manner

8. The Powers of the Mind
An investigation of the powers of the mind will show it unsuited for the investigation of remote and abstruse subjects
It is satisfying in itself to map the powers of the mind
Can we discover the fundamental sources of these powers?
Since they have not been discovered yet, it must be hard to find them

9. The Origin of Ideas Impressions are original, lively thoughts
Sensations
Emotions
Desires
Volitions
Ideas are less-lively copies of impressions
All (or nearly all) ideas are copies of impressions
The test for validity of an abstruse philosophical idea is to find the impression of which it is a copy

10. The Association of Ideas
Ideas and impressions occurring in the mind are connected by general principles
Even the most disorganized thought has some thread of order in it
There are three such principles
Resemblance
Contiguity
Cause and effect

11. Relations of Ideas and Matters of Fact
Mathematical sciences, which are intuitively or demonstratively certain, concern only relations of ideas
They are based on mere thinking
Other objects of investigation concern matters of fact
There is no contradiction in denying them
So what evidence do we have of their truth?

12. Cause and Effect
The senses and memory attest to the real existence of things
This testimony is extended by reasoning about cause and effect
This reasoning moves from a present fact to a remote fact
It does so through the presumption of a real causal connection between the facts
But how is this connection known to hold?

13. Cause and Effect Discovered through Experience
We do not know a priori what effect will follow from a given cause
Only experience allows us to discover the connection, e.g., that bread nourishes
Custom conceals this reliance on experience
We cannot without experience predict a particular effect
Nor can we discover the general relation

14. Ultimate Causes Unknown
The best we should hope for in natural philosophy is to reduce the causes of natural phenomena to a few (gravity, cohesion)
These are based on analogy and observation
The causes of these causes are beyond our reach
Mathematics cannot uncover causes

15. Causal Reasoning Causal reasoning is based on experience
What justifies our use of experience to draw conclusion about matters of fact?
We connect sensible qualities with “secret powers”: bodies with the perceived qualities of bread have the power to nourish us
By what reasoning do we extend the “power” observed in one piece of bread to an unobserved piece?
There is no apparent “medium” to connect the two

16. The Missing Link
There can be no demonstration connecting the observed with the unobserved
The opposite can always be conceived
So the connection could only be established by probable reasoning about matters of fact
All such reasoning is based on similarity
What is the medium connecting the similar to the similar?

17. Begging the Question
It might be said that experience is the required medium
It could serve as a medium only if the future resembles the past
We infer that the future resembles the past only on the basis of experience
But this use of experience then requires the premise that the future resembles the past

18. Is There an Inference At All?
We do not know how to support the inference from the observed to the unobserved
It may be that there is no inference at all
A child learns at once to avoid a hot surface, and no inference seems to be involved

19. Skepticism
Skepticism talks of doubting, suspending judgment, refraining from rash conclusions
As such, it does not ally itself with any of the passions, except love of truth
For this reason, it is stigmatized as libertine, profane, and irreligious
But skepticism about the basis of causal inference does not undermine ordinary reasoning

20. Custom and Habit
The reason we make judgments based on experience and refrain from then when lacking experience is custom or habit
This allows us to conjoin things which in themselves are dissimilar, such as weight and solidity
Custom “is the great guide to human life”
It always terminates in a present sensation or memory

21. Belief
The difference between belief and fiction is not to be found in the idea itself
Instead, it is a feeling found in belief alone
It gives [ideas] more weight and influence, makes them appear of greater importance, enforces them in the mind, and renders them the governing principle of our action”

22. Mechanisms of Belief Belief is an intense idea of something
In the case of the relation of cause and effect, the idea of one thing is intensified in the presence of the idea of another
The same holds for resemblance: our idea of a friend is intensified by a picture of him
And also for contiguity: my idea of my home is more intense upon my approach
Custom accounts for all these phenomena, in harmony with nature

23. Probability
Although there is no chance in the world, our ignorance of causes makes it seem as if there is
Our beliefs about “chances” reflect the intensity of our ideas of each alternative
Our ideas of causes vary in intensity with the number of cases
If enough cases concur, there is belief

24. Necessary Connection
Mathematics deals with clear concepts, but with complicated inferences
Metaphysics deals with obscure concepts, though its inferences are short
The most obscure ideas in metaphysics are those of “power, force, energy, or necessary connection”
What impression lies behind them?

25. Sources of the Idea
Ideas of external objects do not reveal necessary connections
We experience only the conjunction; the power remains hidden
It is thought that experience of our willing a change in one’s body reveals a power
But this pretension will be exploded

26. Willing to Move
The consequences of our willing can only be determined through experience
We do not know how mind and body are connected
We lack control over some parts of our body
We do not bring about movements directly

27. Willing Ideas
It is also thought that will is the power to produce or control ideas
But we lack an impression of this power
We do not know how the mind brings about ideas
We lack control over some ideas
Our control is variable

28. Occasionalism
Nicolas Malebranche and others claimed that only God is a cause, and alleged causes are only occasions for God’s causality
This view detracts from God’s power
It also has philosophical defects
It too-boldly carries us beyond experience
We are as ignorant of any causal power in the mind as in bodies

29. The Origin of the Idea of Power
All we discover through experience is conjunction, not connection
Do we, then, have no idea of power at all?
When there is constant conjunction, we assert that there is a causal connection
The only similarity in the conjunction is repetition of similar instances
We feel a transition, and this feeling is the impression from which the idea of power is copied

30. Causality Defined
A cause can be defined in terms of the feeling of transition
One definition of cause is “an object followed by another and whose appearance always conveys the thought to that other”
This transition is explained in terms of custom and habit

31. Antecedent Skepticism
Descartes sought to prevent error and thus doubted what he could
By bringing his own faculties under doubt, he prevented any possibility of removing doubt
If there were any self-evident starting point for recovery from doubt, its application would involve the faculties in question
A more moderate version is useful: to begin with what is self-evident and make only small steps

32. Consequent Skepticism
Some skeptics focus on the actual deficiencies in our mental faculties
Sensory illusion is generally cited
But it can be corrected through reason
A more difficult problem lies in the natural tendency to suppose that the images of the senses are external, independent objects

33. Doubting the Senses
Philosophy shows that the images of the senses are distinct from independent objects
At best, they are copies of those objects
But the claim of resemblance cannot be justified
We do not know the origin of the images
And we have no way to compare the two
Appeal to God is ruled out
So the teachings of nature are incorrect, and those of philosophy lead to skepticism

34. Primary and Secondary Qualities
It can be shown that the claim of resemblance is contrary to reason
We cannot abstract extension from color, primary from secondary qualities
Secondary qualities depend on the senses and exist in the mind
Primary qualities are no different
So, primary qualities exist in the mind
All that is left is an “unknown something”

35. Skepticism About Mathematics
Abstract reasoning involving space and time fall prey to paradoxes of the infinite
A real line is divided into infinitely many parts, each one of which is infinitely divisible
But this itself is paradoxical, because the initial ideas seem clear, so we are skeptical of our skepticism

36. Pyrrhonism
Extreme skepticism would have us doubt all reasoning concerning matters of fact
But this Pyrrhonism is overcome by our need to act
Nothing of any lasting value results from it—it is mere amusement
So the skeptic should confine himself to philosophical objections into abstract matters, such as causality

37. Mitigated Skepticism
Most people are dogmatic, as this is the most effective way to bring about action
Some skepticism might cure them of this
A just reasoner will always entertain some doubt and caution
Another form of mitigated skepticism restricts human investigation to what lies in experience (not the supernatural, e.g.)