The aim of the Essay is to investigate the origin, extent and certainty of human knowledge.
NOTES:

• His self-depiction in the Epistle to the reader as an underlaborer whose task is getting rid of the rubbish which impedes the development of the new science. Newton's Principia (1687); Boyle; Huyghens. The Royal Society of which Lk was a fellow.
• His desire to show that we know that the metaphysical prerequisites for morality (e.g., personal identity and free will) are satisfied, and that our weak epistemological capacities should make us tolerant of different views and therefore in favor of an open society.

Idea:  Locke uses the term 'idea' to refer at least to three different things:

1. the act of perceiving (e.g., II, 1, 3;  II 10, 2)
2. the mental state (Descartes' subjective idea)

NOTE: to what extent this can be distinguished from (1) is a matter of debate.  Still, Lk is not averse to talking of perception as a passion (as for Berkeley) rather than as an act (II, 1, 25; II, 9, 1)
3. the intentional content of the mental state (Descartes' objective idea) (II, 8, 8)

1. Direct Realism

Problems: bent stick; time light takes to get to us (Lz & Russell);
2. Idealism;
3. Representationalism

Problems: the veil of perception.

• Sensation conveys the ideas of sensible qualities; it provides the starting material on which the mind  works.

NOTE: Standard empiricist account (e.g., Aquinas)
• Reflection conveys the ideas of both the actions and the passions of the mind, e.g., willing (action) and pain (passion).
• Innate ideas don't' exist because innatism is either empirically false (in its strong version), or preposterous and trivial (in its weak version):
1. Strong version: we are born with actual knowledge of (some) speculative principles, e.g., Law of non-contradiction; transitivity of identity etc.  But this must be false because:
• there is no universal consent
• children and savages (!), in whom these principles should not be obscured by prejudice, do not know them.

NOTE: An analogous argument applies to the alleged innateness of non-propositional ideas, e.g., that of God, which not all civilizations have (I,4,8)
2. Weak version: we are born with the capacity to assent to (or know) speculative principles. But this is preposterous and trivial because then:
• all a priori propositions (millions!) would be innate (preposterous)
• any knowable proposition would be innate, (trivial).

NOTE: An analogous argument applies to the alleged innateness of non-propositional ideas, e.g., that of God, which, were present in everyone, would not need to be innate (I,4,9).
Problems:
Descartes' and Leibniz's dispositional analysis of innate ideas.  Note how the dispositional defense works better with ideas (we do have a tendency to carve up the world in a certain way) than with principles which, even the innatists agree, are not universally accepted.
NOTES:
• Lk viewed innatism as refuge of philosophical ignorance and prejudice (link to clearing of the rubbish) and as an attack against epistemological individualism (if I know that P, then I can show P to be true without appeal to authority).
• Instead of innatism Lk proposes experience and abstraction, of which he gives two accounts:
1. selective attention: I have a particular idea of white snow and I attend to it just with respect to those features by which it resembles my ideas of white chalk and white milk (II, 11, 9)

NOTE: here the idea seems to be a determinate idea used in a certain way.  The account is similar to Berkeley's, in that what makes the idea abstract is how we use it, i.e., as a general idea.
2. elimination: I consider ideas of Peter, Paul, and Mary and eliminate what they don't share.  What I'm left with is the abstract idea of human being (III, 3, 7)

NOTE: here the idea seems to be indeterminate.
NOTE: since animals don't use general signs, they have no general ideas, and hence, they do not abstract (II,11,10).
• However, Lk allows for some innate practical principles (e.g., the tendency to avoid perceived evil). But instincts are not represented.

• characterized by uniform appearance e.g., yellow; taste of melon.
• have undefinable names (E 3,4,4)
• the mind cannot make new ones or destroy those that are in the mind (Reason: try if you can).
• In perceiving them, the mind is for the most part passive (The dark room example).

NOTES:
However, sensation is at times changed by judgment (shadowed circle perceived as a sphere).
Molyneux's problem.
The mind has the power to compound different simple ideas and produce complex ideas. So, Lk's model of the mind is analogous to corpuscularianism: one starts with simple entities and obtains the variety of mental life from their composition.
• A simple idea: the idea of solidity:
• the idea of solidity, or impenetrability (that which hinders the approach of two bodies, e.g. our hands, when moved towards each other) rests on the sense of touch;
• solidity applies to what fills space, i.e. bodies, and is insurmountable; hence it's different from hardness, which is mere cohesion of the parts.  A drop of water is not hard because its parts slide with relation to each other, and yet it is impenetrable because if all the bodies in the universe were to press on it equally on each side, it would not give.

1. Hand stretching beyond the edge of the universe.  Then, either matter infinite, or essence of matter more than three-dimensional extension (II, 13, 21).

NOTE: argument is old.
2. God can stop all motion.  Then, certainly he can annihilate this book.  Since there's no motion, no matter can fill the vacuum.  So, a vacuum is possible, and the essence of matter is not merely extension .

D. Primary/secondary/tertiary qualities.

a) the distinction:

• Primary qualities (e.g., solidity, extension, figure, texture, motion/rest)
1. properties of bodies which are utterly inseparable from them and would exist even if no perceiving being existed
2. produce simple ideas in us which resemble their causes: the representational content of the idea of a circular disk is similar to the circularity of the actual disk.

Problems:
• Does the resemblance claim make any sense at all?
• Does Lk have an imagistic view of ideas?
• Secondary qualities (e.g., heat, colors, smells).
1. powers in bodies to produce ideas in us by their primary qualities, and would not exists if no perceiving beings existed

NOTE: powers exist only if they can be activated: Boyle's example of the lock and the key.
NOTE: Berkeley's reading of secondary qualities as "in the mind."
2. arise from the texture of bodies, the arrangement of particles on their surfaces, and ultimately from their real essences (micro-structures);

the causal link between these textures and the ideas they produce is unknowable by us: textures do not resemble the ideas (and the qualia) they cause, e.g. heat & its cause (IV, 3, 13)
• Tertiary qualities: powers in bodies to produce alterations in other bodies by their primary qualities (e.g., capacity of the sun to melt wax).

• long tradition (Democritus; Galileo, Descartes, Boyle).
• its scientific role (primary qualities subject to geometrization)
• attack Scholasticism which held that secondary qualities are as basic as primary ones and that our ideas of them resemble them

• while water can feel cold to one hand and hot to another, a cube never feels square to one hand and round to another

Problem: cases of error in primary qualities? Square towers which look round from far away?
• economy: no need to postulate the existence of secondary qualities in bodies.
• new physiology of perception (vs. Aristotelian): corpuscles impinge on our senses. This explains cases of illusion (e.g. hot water and two hands)
• under a microscope colors often disappear: blood is not red but pellucid with a few red globules.

Problem: but some color is always retained.
• analogy between color and pain (Galileo's Il Saggiatore).

Problem: this shows there may be secondary qualities, but not that the line between them and the primary ones is drawn where Lk says it is.
• things have no color in the dark and it is implausible to think that light causes changes in them. All that happens is that the surface texture of objects causes light to bounce off in particular ways.

• Why and how do primary qualities resemble their representations?
• One might argue that primary qualities are more entrenched (being color-blind vs being size-blind. Bennett's point). This would make the distinction merely one of degree and not of type, as Lk seems to have it.

E. Power.
a) power, what:

• It is an idea of sensation & reflection.
• Active vs. passive power (power to melt and power to be melted)
• How the idea of active power gotten from operations of the mind (active power to move body or make complex ideas) and not from body, since the idea of active power involves that of being an original source of action.

• the will is the power to order the consideration or dismissal of ideas or to prefer rest or some bodily motion to another.
• volition is  the actual exercise of that power, i.e. the actual ordering or preferring. It can be successful or not.

NOTES:
• Criticism of Scholastic faculties, which Locke considers reifications of powers (II, 21, 20)
• Traditionally, volition is distinguished from desire: the former cannot have what the subject considers impossible (presumably, no one wills to fly like Superman); the latter, however, can.
• the execution of an action one wills is voluntary; otherwise, it is involuntary.
• Freedom is the actual power a person has to act (successfully) on the basis of actual or hypothetical volitions, that is, of what he wills or could will. If the person is not free, then his action is necessary.

NOTE: hence, freedom is absence of external impediments to one's actual or possible volitions

• only what has will and understanding can be called free (vs. Hobbes)
• a person who's falling or has a spasm has no freedom with relation to his fall or spastic movement.
• cases of the locked (or paralyzed), but willing to stay, man who is not free to go (or move) if he willed to. Hence:
• the counterfactual (could will).

Problem: should one say that the issue of freedom arises only in relation to actual volitions?  Do counterfactual volitions open too wide a framework?
• free different from voluntary (man locked in room).  In particular, voluntariness not a sufficient condition for freedom.

NOTE: this is against Descartes (Third reply, obj. 12).  However, voluntariness is a necessary condition for freedom.
• necessary different from involuntary (paralytic who wants to stay).
• asking whether the will is free is a category mistake, since freedom is a power, and cannot be predicated of another power (the will).  So, traditional issue of freedom of the will is a category mistake.  A power can be predicated only of an agent, e.g., the man.
• Still, Locke holds that freedom presupposes the capacity to do otherwise, itself presupposed by moral responsibility (IV, 17, 4).  Presumably, he would give the usual compatibilist analysis of "could have done otherwise" as "would have done otherwise had one so willed."

3. Locke holds that we have the power to suspend our volitions, and that this is the source of what is "improperly called free will." (II, 21, 47).  This can be red as an endorsement of contracausal freedom and therefore to open problems of consistency, since he seems to adopt both libertarianism and compatibilism.  Perhaps, however, the passage can be read merely as stating an obvious capacity compatible with determinism.

4. Theory of motivation: what determines the will?

• There are two main views on the subject: internalism (evaluation motivates: the apparent good determines the will), and externalism (the apparent good is at best one of the factors determining the will)
• Lk starts as internalist, but finally chooses externalism because of weakness of will (the drunkard case)
• uneasiness determines the will (changes direction of the will, as it were). The perceived but absent apparent good may (or may not) generate enough uneasiness to determine the will.  So:
• action cannot be caused simply by belief but requires uneasiness, a different mental state.

NOTE: This is similar to Hume's point that volition, requires desire desire.
• The uneasiness need not be about the perceived absent good.