Hume: On the Origin of Ideas

Distinction: Thoughts are distinct from sensations in that they lack
their vivacity. (par 1)
Clarification: To have a concept of love or anger is far different
than having the experience of such emotions. Concepts are copies of
experiences; they mirror them. (par 2)

Definition: THOUGHTS or IDEAS are weaker versions of IMPRESSIONS,
which are perceptions of the external world, internal emotions,
desires, or motions of the will. (par 3)

Limit of Thought: We has never been experienced may never be conceived
and only contradiction exceeds our powers of imagination. (par 4)

This limit is narrow: We can only conceive that which we have
experienced, "compounded, transposed, augmented, or dimished" as the
mind wills. Thus we can think of things that do not exist by combining
two concepts derived from our experience. (par 5)

Proof: Argument 1: Analysis of thoughts resolves them into simple
copies of some preceeeding feelings or sentiments. (What is a simple
idea? A colour, a taste, a smell, a shape...) Thus, our idea of God is
simply the product of our augmenting, without limit, the qualities of
goodness and wisom we find within our own mind. If we investigate, we
will find that all ideas are made up of copies of similar impressions.
In order to prove this thesis wrong, simply provide evidence of the
existence of an idea that is not derived from an impression. (par 6)

Argument 2: People without the the sensory faculties of sight or
hearing do not have the impressions from which to form the
corresponding ideas or concepts. In the same way, you can't imagine
what a pineapple tastes like unless you taste one first. In addition,
it's possible for beings to exist with senses and corresponding
concepts that we have no understanding of. (par 7)

The one idea not derived from an impression (see par 6): Our colour
spectrum is constituted by our ideas of of each individual colour and
the corresponding impressions from which they are derived. Now, we can
imagine someone who has had sight his whole life and seen many
colours, save one specific shade of blue. If you gave this person a
paint chip with a gap where the missing shade of blue should be, he
should be able to fill in the gap from his own imagination. Therefore,
simple ideas are not necessarily derived from corresponding
impressions. But this is so singular a case as to be barely worth
mentioning, and it should not deter us from adhering to our general
maxim: (par 8)

Matters of Fact and Relations of Ideas

Hume draws a distinction between two kinds of ideas, relations of ideas and matters of fact.

Relations of ideas: They are knowable a priori. We can understand them by the mere operation of thought. Their truth does not depend on empirical knowledge, and hence can be known to be necessarily true, meaning that we could not conceive of it otherwise. Examples of this are 2+2=4, Pythagoras's Theorem, etc..

Matters of fact: They are knowable a posteriori. We require experience to ascertain their truth. The contrary of every matter of fact is possible. This means that we can conceive of things being otherwise; no matter of fact is neccessarily true. Examples of this are propositions such as 'the sun will not rise tomorrow.' We cannot demonstrate this is false, because if it were, it would have to imply a contradiction, and to conceive of it would be impossible.

The interesting thing about matters of fact is that all reasoning about them depends on assumptions about the relationship between cause and effect. We assume that cause and effect relations we have observed in the past will be reflected in the future. We assume for every effect there is a cause, and that similar causes have similar effects. (So if I hold up this glass and let it go it will be just as likely to fall as if I let go of a rock.)

Hume notes that these assumptions are a posteriori. This means that there is no necessary connection between any cause and any effect. We can conceive of a different effect for any cause and vice-versa. Thus the logical connection between cause and effect cannot be established demonstratively, because we can imagine cause and effect relationships as being otherwise without implying a contradiction. We have developed our knowledge of cause and effect by experience, but this does not constitute certain proof of their connection. For an example, he cites Adam in the Garden of Eden, having no idea that fire would consume him or that water would drown him. We can also just as easily imagine Adam in the pool hall, with no clue which way Hume's billiard ball is going to go once struck.

We cannot establish the certainty of the connection between cause and effect with probable reasoning either, because it is based on the assumption that nature is uniform, that the future will be like the past. And this is the skeptical claim that Hume is making; there is no way we can be certain that the future will necessarily be like the past. Take it from the man himself:

"Were any object presented to us, and were we required to pronounce concerning the effect which will result from it without consulting past observation, after what manner, I beseech you, must the mind proceed in this operation?"

"The mind can never possibly find the effect in the supposed cause by the most accurate scrutiny and examination." (pg. 203R).

Hume comes to the conclusion that there is no necessary connection between cause and effect. We only observe a constant conjunction between events and then the mind assumes that there is a connection after it has been habituated into expecting that nature will behave in a uniform manner.

Berkeley's Abductive Argument for the Existence of God

If we accept Berkeley's argument that material substance is an illusory absraction, then how do we explain where our ideas come from? There are 3 options: (1) other ideas (2)ourselves (3) some other spirit.

In par. 25 he rules out (1) with this argument:

(1) Ideas are manifestly passive—no power or activity is perceived in them.

(2) But because of the mind-dependent status of ideas, they cannot have any characteristics which they are not perceived to have.

Therefore,

(3) Ideas are passive, that is, they possess no causal power. (http://plato.stanford.edu/entries/berkeley/#3.1.3)

He rules out (2) with the observation that although we have some power over our ideas, for example we can imagine what we will, we do not have control of our sensory ideas (remember back to Locke's example of looking at the sun). However, Berkeley does not conclude from this that material objects must exist, but rather that "there is therefore some other will or spirit that produces (our ideas) (par. 29).

Berkeley corroborates this claim with evidence from the orderly and coherent nature of our ideas. They are not excited at random like the ideas generated by human willing, but are "a regular train or series, the admirable connection whereof sufficiently testifies the wisdom of its author" (par. 30).

If a tree falls in the forest, and nobody hears it, does it make a sound?

Berkeley says no.

Berkeley is not persuaded by Locke's arguments for believing in the external world. But he does not think that not believing in the existence of a world of mind-independent objects is anything to get excited about. All that Berkeley is willing to admit into his ontology are ideas and the minds that perceive them. Here is his argument:

(1) We perceive ordinary objects (houses, mountains, etc.).

(2) We perceive only ideas of those objects.

Therefore,

(3) Ordinary objects are ideas.

This is a valid argument, but Locke has a response to it. Locke would block Berkeley's conclusion by distinguishing between two sorts of perception. He would say (1') We mediately perceive objects and (2') We immediately perceive our ideas. Of course, Berkeley knows this and he has a response.

Berkely argues that there are no good reasons to accept Locke's claim that our ideas our representations of objects. Here is his counterpunch:

"But say you, though the ideas themselves do not exist without the mind, yet there may be things like them whereof they are copies or resemblances, which things exist without the mind, in an unthinking substance. I answer, an idea can be like nothing but an idea; a colour or figure can be like nothing but another colour or figure" (par. 8).

We cannot step out of our own skin and objectively compare our ideas with the objects that they supposedly represent. So we have no solid ground upon which to assume that they do so.

If an idea can only be like another idea, then what can we say of the existence of a world of mind-independent objects? His answer is, nothing, because he says no other way to describe material objects except in terms of our ideas.

As for Locke's distinction between primary and secondary qualities, Berkeley attacks it as unintelligible. His argument is part of a larger argument against the possibility of abstraction. He does not think we can conceive of an object's primary qualities by abstracting away all of the secondary qualities (everything about the object that depends on our senses: taste, see, sound, feel, smell). He says that primary qualities cannot be conceived in absence of some secondary qualities. In paragraph 10 he asks if any of his objectors could conceive of a triangle without colour, or any other sensible qualities.

Berkeley thinks that the craziest abstract idea of them all is material substance. He says that material substance is a vague and indeterminate notion, with no other meaning than the idea of being in general. Material substance is supposed to support all of the mind dependent qualities that we perceive; it is some indeterminate substratum that makes our ideas possible but which we can never have an idea of.

He says that the notion of material substance is incomprehensible and contrary to commonsense. It depends on the possibility of objects existing independently of our perceiving them, and Berkeley says that is a manifest contradiction because to be an object is simply to be a bundle of ideas.

The Master Argument: Berkeley is willing to rest everything he says on this (par. 22-23).

… I am content to put the whole upon this issue; if you can but conceive it possible for one extended moveable substance, or in general, for any one idea or any thing like an idea, to exist otherwise than in a mind perceiving it, I shall readily give up the cause…. But say you, surely there is nothing easier than to imagine trees, for instance, in a park, or books existing in a closet, and no body by to perceive them. I answer, you may so, there is no difficulty in it: but what is all this, I beseech you, more than framing in your mind certain ideas which you call books and trees, and at the same time omitting to frame the idea of any one that may perceive them? But do not you your self perceive or think of them all the while? This therefore is nothing to the purpose: it only shows you have the power of imagining or forming ideas in your mind; but it doth not shew that you can conceive it possible, the objects of your thought may exist without the mind: to make out this, it is necessary that you conceive them existing unconceived or unthought of, which is a manifest repugnancy. When we do our utmost to conceive the existence of external bodies, we are all the while only contemplating our own ideas. But the mind taking no notice of itself, is deluded to think it can and doth conceive bodies existing unthought of or without the mind; though at the same time they are apprehended by or exist in it self. (PHK 22-23)

Any objections?

Locke: Proof for the Existence of the External World

Locke offers a series of rhetorical arguments for the acceptance of the existence of the external world. Here is a brief summary of them.

1. Locke agrees with Berkeley about the fact that the only proof of the external world is the ideas caused by our sensations, and there is no necessary connection between the existence of an idea and the existence of its cause. Neither philosophers think Cartesian certainty about a world of mind-independent objects is possible.

Locke still believes that there is a world external to our ideas, however. The first thing he suggests we do is "lower the bar" for what we call knowledge. The ideas caused by our sensations are the best evidence we have of "the existence of things without us," and he claims that this deserves to be called knowledge. But this is certainly not what Descartes wanted to call knowledge.

2. The Performative Argument: Locke says that anyone who is skeptical of the external world, who thinks that she is dreaming, would not bother to disagree with him. He says that anyone who is so skeptical to doubt their sensations "will never have any controversy with me, since he can never be sure I say anything contrary to his opinion. And later, "if all be a dream, then he doth but dream that he makes the question, and so it is not much matter that a waking man should answer him." If skeptic really believed his own arguments, he would not reply to Locke since Locke is part of the external world that he thinks is dubious. This is a bit of cheap shot on Descartes. Descartes' doubt is part of a method he came up with in order to attain certainty. It was part of a thought experiment. He never said that he believed he was dreaming or being deceived by an evil demon, he just supposed that it was possible.

3. Where else would our ideas come from? Our sense-organs do not magically generate ideas all by themselves. Nobody gets the relish of a pineapple until they travel to the West Indies and eat one.

This argument by itself is not very compelling, but it is part of a larger abductive argument (an argument to the best explanation).

4. Our ideas are caused independently of our willing: If I look at the sun, I cannot keep myself from having ideas which it causes in me. If we had control over our ideas, what would keep us from only producing pleasurable ones in our minds? We suffer great pains, and if there were no exterior cause, these painful ideas in our minds would either never or always bother us.

5. Corroboration of the senses: One sense sometimes verifies are falsifies ideas given from our other senses. For example, we can figure out that a stick in water isn't actually bent by pulling it out.

6. Pragmatic appeal: Our senses are good enough for keeping us alive. They serve our purposes well enough. Later on, Locke says that anyone who in his ordinary affairs takes up Cartesian skepticism would be sure of nothing more than dying quickly.

If our Cartesian dreamer should doubt their veracity, why doesn't he just go stick his head in an oven? This is a fallacious appeal to force. There's a cool website that lists fallacies here: http://www.fallacyfiles.org/adbacula.html This is what they had to say about this fallacy:

Appeal to Force is a technique of distraction which occurs when force, or the threat of force, is used to "win" a debate. More frequently, it is used to cover up the fact that the threatener is losing. The name "argumentum ad baculum" alludes to the use of a stick, or club, to beat someone. This fallacy is committed whenever force or the threat of it is introduced into a rational discussion in order to derail it. It is a fallacy simply because force is not an argument.

Locke concludes by saying that all he has been arguing for is the probable existence of the external world, at least when we are not perceiving it. He concludes that though it is very likely that there exists an external world that continues to exist when we are not perceiving it, he cannot really say that this probablity constitutes knowledge. (See the end of par. 9, he takes of all the people in the world, and that when he is alone, he cannot really be sure of anything more than his perceptions, and even then, how sure can he really be if the only evidence he has for trusting them is that they are useful for staying alive?)