Monday, November 21, 2011

Can I Reason My Way To Moral Principles? Or Do I Need Some Other Kind of Knowledge?

Preamble  (Warning: I haven't proof read this entry yet)
    For those of you who haven't been following or have forgotten what I've written about Kant here are some technical terms that will allow you to understand what I've written here.  This is a section of my paper that I'm working on.  For some reason when I write an essay that I need to turn in, I get writer's block, but if I write on the same topic in my blog, it comes out more easily. So that said, any feedback is welcome, it'll probably help me improve my paper.
Back to the technical stuff.  I think all you need to know is that the Formula of Universal Law (FUL) is the law that says what ever action I'm thinking about doing, if I want to know if it's morally correct or not, I test whether it passes this test: "I ought never to act except in such a way that I can also will that my maxim should become a universal law".  
Should We and Can We Exclude All Empirical Facts from Our Moral Reasoning?
     Kant says we should exclude empirical considerations if we are to come up with a purely rational system of ethics.  The thought is we cannot learn anything about what is morally right by appealing to what people actually do.  There are 4 main problems with trying to come up with moral principles by referencing empirical facts:  First, convention doesn't tell us what is right, it only tells us what convention is.  Think of slavery, it was convention at one point in time but few people would argue now that is was right.  If moral philosophers had appealed to convention at that time they would have concluded that it was morally right.  Second, observing individual actions tells us nothing about the motives for the action--perhaps the motive for the action was self-interest; these are unknowable to the observer, and given humans' capacity for motivated reasoning, probably also unknowable to the agent.  Given these facts it would be impossible to abstract any general principle of action by observing behaviour.  There is a third kind of empirical moral reasoning Kant wants to exclude, this is moral judgment by appeal to examples.  Every example (think of a fable or religious story) that we hold up as "good" action has to be good because of some principle; so it follows, we would do better to discover the principles that allow us to call certain behaviours "good"--a behaviour can't be good just because we say it is.  The fourth type of empirical consideration we should ignore are facts particular to the conditions of humanity.  The reasoning is that because all moral principles will be rational principles the laws that are derived from reason must apply to all rational creatures.  Moral principles would lose their status as absolute if we said that certain ethical laws only apply to humans but not to some other rational being.
     That we should derive our moral principles from reason is prima facia appealing, but before we throw our lot in with Kant and divorce empirical facts from our moral reasoning there are two issues we should explore.  The first is whether--with the possible of exception of social norms--it is even possible to eliminate empirical content; and second, if it is desirable. 
     Is it possible to have an ethical system that excludes empirical considerations?  To answer this question there are two species of empirical fact I think we should explore: internal and external.  By internal I mean facts about human psychology, and by external I mean facts about the world.  Although Kant makes not direct reference to human psychology I think he considered it a part of the "contingent conditions of humanity" (p. 408).  We also might be able to infer that there is something particular to humans, in respect to their capacity to reason because in several places Kant refers to "human reason" in the context of it being something different than that of a purely rational being (p. 404, 408).  
     If we accept that there are psychological traits that are particular to humans and these traits distinguish us from "purely rational beings" it seems that we would do well to discover how these  psychological traits influence our reasoning.  Consider the analogy of a computer.  If we want a write an algorithm for a computer we need to know something about its operating system.  We need to know what kinds of operations a certain operating system does well and does poorly; if we don't take these things into account and assume that whatever the computer spits out is correct, we might have some problems.  It seems that the same goes for humans.  We have a law--the FUL--which we want the rational part of the mind to apply to maxims of action.  But to assume that whatever the rational mind spits out is correct is to overlook how things can go wrong.  Psychology has discovered many ways which we can corrupt our reasoning process: confirmation bias, wishful thinking, confusing cause for effect, motivated reasoning, and so on.  If we fail to take into account how our reasoning can go awry, we are likely to come up with incorrect answers and have no way of knowing they are so.  In a way there's a sort of chicken and egg problem here; we can't have much confidence in our reasoning unless we understand how it can go wrong but we require reasoning to discover how our reasoning can go wrong.  let me explain...
     The scientific method is a good example of how our psychological shortcomings are taken into account so we have a better chance of reasoning to the correct conclusion.  The use of double-blind, placebo controlled, replicated studies helps to control for our cognitive biases.  The more we know about human biases, the better we can control for them in our reasoning.  In science, we learned about our cognitive biases in conjunction with doing scientific research; the approach was not binary.  I think the same holistic approach will yield comparable benefits in moral reasoning.  The more we become aware of our cognitive biases and blind spots, the more effectively we can correct for it in our reasoning.  So, given our human proclivity for motivated reasoning, amongst other cognitive shortcomings which Kant repeatedly points out, it does not seem possible that we could have much faith in the correctness of our reasoning without at least a minimal understanding of these phenomena.  On this view, an ethics devoid of all empirical considerations might work in purely rational beings without any of our disadvantages, but as humans we require some empirical knowledge of our psychology before we can put any stock in our "rational" conclusions.
External Empirical Facts (I.e., Facts about the World)
     Kant wants to deny that empirical conditions can substantially influence the outcome of applying FUL—its prescriptions will hold in all contingencies. But it seems that there may be some cases where facts about the external world influence the acceptance of rejection of a maxim by the FUL.
      Suppose there is a plant called the Aleeval plant which for whatever reason cannot be grown commercially, is necessary for the maintaining our global climate in equilibrium, and whose roots are the most delicious food in the world. When human population levels were such that even a steady diet of the root for every man woman and child would have no measurable impact on the plant's population, the decision of whether to eat the Aleeval root did not enter the moral real. Put otherwise, if I asked “should I eat Aleeval root to my heart's content?” the action would have been universalizable. But the empirical facts about the world have changed, and now if everyone eats the root, all life on our planet will die; if I ask “should I eat Aleeval root to my heart's content?” the FUL will reveal the action is not universalizable. Eating the Aleeval root has entered the moral realm. So it seems, contrary to what Kant says, the FUL will not always yield objective answers, some will be contingent upon empirical facts about the world.
     There is a reply open to Kant, which is we are applying the wrong maxim to the FUL. As it is now our test maxim is “is it permissible to eat unlimited Aleeval root?”, and given this maxim, changes in the world will yield different outcomes. However, perhaps the correct maxim is “should I consume resources at unsustainable rates (i.e., beyond replacement rates)?” If this is our maxim then empirical facts can vary and this will determine whether the maxim comes into effect, as with any ethical situation, but its standing as a universal moral principle will remain constant. In the context of our example this means if I apply the more general maxim then human and the Aleeval population can perpetually rise and fall and my actions , so long as I follow the general maxim, will always be appropriate. This reply works well but Kant says that the FUL will output the correct answer to any subjective maxim. So, strictly speaking, the generalization reply is not open to him. 

OK, that's enough for now.  I'll talk about if we should exclude empirical facts from our moral reasoning later...gotta submit my rough draft which was due 4.5 hours ago....



Tuesday, November 15, 2011

Why Are Locke's 'Complex Ideas' Easier to Comprehend than his 'Simple Ideas'?

Locke's Complex Ideas

     Most of what we've talked about so far (in relation to ideas) concerns ideas, generally considered, and simple ideas.  Recall that all ideas have as their source either perception or reflection on the operations of the mind; and in the case of simple ideas the mind is always passive (II. xii. 1).  In other words, where simple ideas are concerned, the mind cannot create them nor can the mind have any complex idea which is not made up of one or more simple ideas.   Let's take a more detailed look at what this means and what Locke has to say about complex ideas.
     The general theory is that simple ideas are the material out of which we construct complex ideas.  When we construct complex ideas the mind is active; the mind is active in three main ways: "1. combining several simple ideas into one compound one, and thus all complex ideas are made. 2. By  bringing two ideas, whether simple or complex, together; and setting them by one another, so as to take a view of tehm at once, without uniting them into one; by which way it gets all its ideas of relations.  3. Separating them from all other ideas that accompany them in their real existence; this is called abstraction: and thus all general ideas are made" (II. xii. 1).
     Lets break this shit down...wika wika... The first type of activity of the mind that produces complex ideas is compounding, or mixing of 2 or more simple ideas (that we already have stored in our memory).  Example of such ideas are: beauty, gratitude, a man, an army, the universe.  When we contemplate things like beauty or the universe we consider them to be one unified thing but they are made up of many simple ideas.  'Beauty' is made up of all our different ideas of physical qualities along with the idea of perfection; 'the universe' is made up of the collection of all the ideas of things that are in the universe.  There are an infinite number of ways and combinations we can unify different our various basic ideas to form new ones, much like there is an infinite number of ways we can combine physical materials to form new objects.   At the end of the day, however, our complex ideas are ultimately comprised of simple ideas, just as the most complex objects are made of their fundamental materials.
      Of the infinite ways simple ideas can be compounded they will all generally fall under 3 headings: Modes, Substances, and Relations.  A mode is like a concept; it doesn't correspond to anything in the physical world.  Things in this list include, beauty, theft, politics, happiness, triangle.  You may say, "well, triangles exist in the physical world".  True, but the concept of a triangle (ideas of closed figure, 3 sides, 3 interior that add up to 180 degree) doesn't require that a physical triangle exist. 
     Substances are combinations of simple ideas that represent distinct and particular things that exist in the physical world.  For example if we affix to the idea of substance the simple ideas of weight, hardness, ductility, and fusibility we have the idea of lead.  If we affix to the idea of substance the simple ideas of a human-like shape, with power of motion, thought, and reasoning, we get the complex ideas of 'human'.  We can also further combine complex ideas of substance.  If we combine the idea of 'a soldier' with the idea of 'several' and we get the new substance (i.e. thing) 'army'.
     Finally, there are complex ideas of relations where we compare one idea (simple or complex) with another to form a new idea.   For example, if I compare the idea of a small box with a big box I can get the new idea of 'bigger'.
     Despite our capacity to form even "the most abstruse ideas, who remote soever they may seem from sense, or from any operation of our own mind...are derived from sensation or reflection, being no other than what the mind, by ordinary use of its own faculties, employed about ideas, received from objects of sense, or from the operations it observes in itself about them" (II. xii. 8).  In other words, no matter how complicated your ideas and concepts, they are all reducible to their origins as simple irreducible ideas.
    You may have noticed I di'int go into detail about abstraction and are very much irritated at me for not doing so.  I feel your pain.  I'll talk about that laters...



Monday, November 14, 2011

The Mission: To Determine How Locke Thinks We Perceive Ideas of Concepts

     In the first chapter of book two of The Essay Concerning Human Understanding Locke says all knowledge (the materials of which are ideas) comes from one of two places: "external, sensible Objects; or about the internal operations of our minds, perceived and reflected on by our selves."  Basically, this means ideas can come from either sense perception of the external world or internal reflection of our mental processes.  In the last post we focused on the former (in terms of sense perceptions and memories of past sense perceptions) and I didn't think there was definitive evidence for a purely imagistic interpretation; I think we could also ascribe to Locke a less simplistic representationalist theory of mind.  Bottom line, there's weak evidence but there's no knock down evidence (IMHO).

Ideas from Sense Perception Revisited
     Just as I finished writing this last line I found the following passage (II. i. 2.) "[...] our senses, conversant about particular sensible objects, do convey into the mind several distinct perceptions of things [...] and thus we come by those ideas, we have of Yellow, White, Heat, Cold, Soft, Hard, Bitter, Sweet, and all those which we call sensible qualities [...]."  
     I think this passage indicates that sense perception-produced ideas are imagistic, but not necessarily visual.  Obviously, when we sense coldness we don't see anything, but in a general way we can say there is a sensible quality to coldness.  Of course, in this context we are not talking about having these general ideas as abstracts; how do I perceive them in non-sense (ha!) situations?  For example, in this paragraph we are talking about "coldness" in an abstract way, it is unlikely that any of you felt cold because you read that word.  Moving on...

Ideas from Perception of the Operations of the Mind
     How does Locke talk about ideas that we obtain through perceiving and reflecting on the operations of our own mind?  Lets define operations of the mind first.  The operations of the mind are the thoughts and attitudes we have toward the (usually?) sense ideas we have.  For example, perception, thinking, doubting, believing, reasoning, knowing, willing or any other mental activity like abstracting, compounding, and comparing, of which we can be conscious.  Regarding these internal objects of the mind Locke seems to take the position that we can only be said to be having them when we are conscious of them.  Just as with sense ideas, the more I attend to the details the more clear and distinct the ideas will be, so too of ideas of operations of the mind.  "Yet unless he turns his thoughts that way, and considers them attentively, he will no more have clear and distinct of all the operations of the mind...than he will have all the particular ideas of any landscape...who will not turn his eyes to it (II. i. 7.). 
     This position makes sense in that in is a bit strange to say you have an idea if you aren't conscious of the idea; but on the other hand I'm not sure it's a necessary condition.  For example, you 'doubt' that sweet baby Jesus was sweet--maybe he cried a lot.  In order do say you have the idea of doubting SBJ was sweet do you have to be consciously aware of the thought "I doubt SBJ was sweet"?  I think it make more sense to say this is a disposition.  
     Consider another example: you are doing some maph problems.  In order to 'have' the idea of addition and subtraction to you have in your mind the the thought "I am adding this...weeeee! and now I'm subtracting this......woohoo!...This is me adding and subtracting".  I'm not sure this is how it happens.  I can't speak for others but if I had a little voice talkin' jive like that er'time I did maph it would take me years to do a problem set.  It makes more sense that these ideas are latent in some way.  We can call them to the fore of our consciousness if we want, but I certainly don't need to in order to do maph...and I'd say the fact that I can add and subtract is fairly good evidence that, in some capacity, I have the ideas of addition and subtraction.
     OK, finally, after much torture I think I have a passage of some relevance to our task of interpreting what Locke thinks about ideas as concepts.   In his discussion of how our mind abstracts from the particular to the general he says something like this:  a) we use words to stand for our internal ideas of particular things, b) if we had to make a word for each particular thing of which we have an idea, we'll need a heck of a lot of words (infinity), c) to prevent this we abstract general ideas from particular ideas "by considering them as they are in the mind such appearances, separate from all other existences and the circumstances of real existence, as time, place..." (II. xi. 9).  So there we have it! Finally, the smoking gun!  General ideas (abstract ideas) are appearances.  For further confirmation, a few lines later Locke refers to general ideas as "precise, naked appearances in the mind". 
     There is still a question about how we should treat simple ideas about the operations of our mind (non-sense ideas) because when we engage in composition and enlarging we "put together several of those simple ideas [the mind] has received from sensation and reflection, and combines them into complex ones" (II. xi. 6).  I can understand how we form new ideas from those derived from perception but we are still unclear about the representational content of our ideas of "doubting", "believing", "reasoning", and "knowing".  So, saying that we mix simple ideas from both perception and reflection to get complex hybrid ideas doesn't give us any clue as to what the mind-operation idea content is like when we perceive it.  And then there's the problem of what it is like to 'have' those complex ideas when we recall them after having had them.
     There is one final passage methinks fit to discern the views of Locke in regards to whether he thinks our ideas (both of perception and reflection) are imagistic, but of course we might contend that it is (once again) an extended metaphor and not necessarily a precise description.  Here we go: external and internal sensation "are the windows by which light is let into this dark room" (i.e. the theatre of the mind). "For, methinks, the understanding is not much unlike a closet wholly shut from light, with only some little openings left, to let in external visible resemblances, or ideas of things without; would the pictures coming into such a dark room but stay there, and lie so orderly as to be found upon occasion, it would very much resemble the understanding of a man, in reference to all objects of sight, and the ideas of them" (II. xii. 17).  Well, finally! Although, I have no idea how we have images of ideas that arise out of reflection (concepts, attitudes, etc...); but apparently they are also like "picture in a dark room" upon which we occasionally shine the light of awareness.  Or as the late great Ronnie James Dio would say, "like a rainbow in the dark!"

Sunday, November 13, 2011

The Psychology of Grappling: Wrestling vs BJJ

Wrestling vs Brazilian Jiu Jitsu

     I've had a couple of glasses of wine so I apologize in advance for any incoherence beyond the usual.  My whole life (20 years of it, anyway) I've been a wrestler but in the last 2 weeks I've finally started to understand what it means to be a Brazilian Jiu Jitsu (BJJ) player.  
     Lets begin first with wresting.  Wrestling is all about breaking your opponent's will.  If you can establish physical dominance, then he will break mentally, then you win.  Wrestling practice focuses on establishing physical dominance---both strength and enduance; technique, although important, is only one of the means by which you accomplish your ultimate goal--breaking the will.  In practice the coach tries to break your will by pushing your physical and mental limits; this prepares you for competition.  I have to admit, there is something deeply satisfying when you break your opponent's will.  You can usually feel when it happens.  It satisfies something primal.
     BJJ is different.  BJJ is all about outsmarting your opponent.  It's physical chess but you don't win by force, you win by anticipating your opponents moves and countering them.  I've messed around with BJJ on and off for over a decade but it's only in the last 2 weeks that I finally understood what it was about.  For the last 10 years I've been doing BJJ as a wrestler; but BJJ doesn't work that way.
     The beauty of BJJ is that a less physically gifted opponent can beat the physically gifted opponent if he's clever.  The most difficult thing for a wrestler to do is to adopt the practice mentality of BJJ.  In wrestling you never ever ever let yourself get pinned (or beaten in any way) in practice because if you allow yourself to get beaten in practice it will happen in competition; also you will develop a mentality of losing.  In wrestling practice, if you are going to get pinned in practice or taken down, you fight out of it as if your life depended on it--as though you were in a match.
     BJJ is the opposite.  In BJJ practice you allow yourself to get beaten to understand what not to do and to practice getting out of that situation.  The mentality is the opposite from wrestling; in BJJ practice, the more you lose, the more you learn--assuming you analyze why you lost and how you might escape next time.  In fact, many BJJ players will intentionally allow their practice opponents to put them in a bad situation in order to figure out how best to escape it.  
     The most difficult thing for a wrestler doing BJJ is to adopt the mentality that it's ok to lose in practice.  For ten years I was a wrestler doing BJJ--this explains why I plateaued after 2 years, but as of a few weeks ago I had this revelation.  It's not easy undoing almost a lifetime of habits but it's the only way to learn...

Or maybe I'm just getting too old for the wrestling mentality...

Saturday, November 12, 2011

What Does "Bigger Than" Look Like in the Mind? Part 1 Locke's Ideas

The Prolem: Are All Locke's Ideas Necessarily Imagistic?
     Those of you who are facebook friends know I that I recently posted about a little issue I'm having wif my Locke paper.  Here's the prolem: most of my analysis and criticisms of Locke's epistemology rest on the premise that, for Locke, all ideas are images in the theatre of the mind.  I've read a couple of secondary sources that corroborate this interpretation but after frantically scanning my paper last night I realized that I don't a any direct quote from Locke to support this assertion.  
     Now, it is fairly evident that he thinks ideas caused by sense perception are images but Locke is aware that there are other types of ideas.  Locke says we get all our ideas one of two ways: through sense perception or through reflection.  By reflection he means comparing, mixing, and abstracting from the sense perception ideas.  For example, I have an idea (image) of a chair and of a large chair.  By comparing these two ideas I can create the new ideas of size and relative size, or "big" and "bigger than".  That much is clear in Locke, but what isn't clear is the phenomenological (what-it-is-like-to-have-ness) properties of the ideas size or "bigger than".  Another way to state it would be to ax, what does it mean to experience ideas of concepts?  This is the prolem I'm having; I'm not sure what Locke thinks about this...so, it's time to do a little reading of the primary "litra-cha".

Ideas Produced by Sense Perception
     Lets start with what I know, or at least what I think I know about how Locke thinks about ideas produced by sensory perception (did you get all that?).   The relevant passage is this, "But our ideas being nothing, but actual perceptions in the mind, which cease to be any thing, when there is no perception of them [...]".  So from here it appears fairly easy to ascribe an imagistic theory of mind to Locke but now I'm not so sure.  Sure he says ideas are perceptions in the mind but does this necessarily mean the perceptions have to be images?  I don't think this passage on its own is sufficient to make that case.
     Lets consider some of the language he uses to talk about perceiving ideas, in the context of memory, that occur in this same paragraph.  He says the purpose of memory is to "revive again in our minds those ideas, which after imprinting have disappeared, or have been as it were laid aside out of sight".  To talk of ideas "laid aside out of sight" certainly sounds imagistic, but notice he qualifies the phrase with, "as it were" in order to indicate an analogy, not a statement of fact.  Still no verdict.
     However, later in the paragraph, again discussing the purpose of memory, he says that memory allows us to "bring in sight, and make appear again, and be the objects of our thoughts, without the help of those sensible qualities, which first imprinted them there".    Again, phrases like "bring in sight", "make appear again" and "objects of our thoughts" sound very imagistic but there is no reason why Locke my not be using them as analogies.  In particular the phrase "objects of our thoughts" does not necessarily imply images, he might simply be saying "the content of the idea about which we are conscious".  I can't see why this commits him to an imagistic theory of mind, or even a phenomenal theory of mind.  
     He could be just about any brand of representationalist.  All he's really saying is that there is something in the content our perception of 'X' and in our recalling our perception of 'X' that are similar (the same?).  Maybe in the case of sense perception we can ascribe an imagistic or phenomenological theory to Locke but there's nothing that unusual in saying our memory of a perception and the actual perception have some imagistic qualities in common.  In regards to ideas and recollections of concepts, however, I don't think we have any evidence one way or another to determine Locke's position....more research


Wednesday, November 9, 2011

A Bird Is a Word: Having Locke's Ideas

Having Ideas
     What does it mean to have an idea?  Does it require we have some image in the theatre of our mind?  Where do ideas come from? Can we make our own or do they all come in through the senses? For contemporary philosophers 'having a idea' usually implies some sort of disposition; something like, if a circumstance arose where a collection of beliefs and images were appropriate then I could have conscious access to the idea.  So why disposition?  Well, I think it has something to do with the fact that we can't simultaneously hold all of our ideas at the fore of our consciousness (how confusing would that be?) but we need to explain how we can access ideas we've had in the past. 
    One thing about dispositions is that they imply that you've had the idea before but you've relegated it to some place in your memory for future use (appropriate circumstances/context or maybe just daydreaming...).  So, at some point the idea "got into you"...unless of course you were born with it; but that's a different topic.  
      If I tell you to put the idea of a bird in your mind, what happens?  You probably get some sort of image of a bird.  Now think about where you got your idea of the bird.  The story is probably something like, when you were a kid out with your parents, there was a bird in your visual field and your parents indicated it and told you to call it a bird.  The point is that you had some sort of sensory experience that initially "produced" in your mind the idea of a bird.  And because you don't always go around with the idea of a bird at the front of your consciousness, the idea of 'bird' is stored somewhere for later use.   The main point for Locke's purposes is that it all started with you having a sensory experience of a bird, which incidentally, is a word.
     For Locke all ideas had their origins as sensory experiences...well, mostly.  Sensory experiences provide the raw material from which the activities of our minds can form new more complex ideas by comparing, compounding, and abstracting from the raw material. So, we can compare this type of 'having an idea' (havingE an idea) with the dispositional type (havingD an idea).   To make it more explicit 'havingE' an idea means something like seeing a picture of something in your head whereas the 'havingD' an idea means that it is contained in your memory but you can only really 'haveE' the idea in your memory when you have already had it and pull it to the fore of your consciousness.
     For Locke there is really only havingE ideas; we can't haveE ideas we are not directly conscious of in the sense that we must perceive them in the theatre of our mind as an image.  For this reason we can interpret Locke as saying the experience of sensory perception and the experience of recalling something we previously experienced will in some way be the same sort of experience; they both involve conscious awareness of some image in the theatre of the mind.
     Ok, so lets get that straight one more time.  If I haveD an idea of a bird (which is a word) stored in my memory the only way I can haveE that idea is if I perceive it as an image in the theatre of my mind.  Also, I can haveE an idea of a bird if I'm looking at a bird--the physical properties of the bird produce in me a mental image of...a bird!  So here's the quextion: if both recalling an idea and havingE an idea produced in our minds through sensory perception both involve perceiving some mental image, how can we distinguish between the two types of experiences?

     In the term paper I'm working on this issue is a sub-issue, here's a little bit I've written on it so far, I apologize for the lack of ebonics...I hope you can still understand me :)

Btw, I enjoy writing in my blog way more than writing essays...why?  This essay is KILLING me!

The Relation Between Sensing and HavingE ideas
     It is quite apparent that Locke sees a close relation between sensing something and havingE an idea of that thing. However, this does not necessarily commit him to the view that this is the only way we can haveE ideas because he speaks of havingE ideas when we dream, remember, abstract, and think of things in their absence (Stuart 40). It is clear from several passages that Locke maintains there is—perhaps--a self-evident difference between havingE ideas produced by perception and havingE ideas by recalling them.
      To make his point Locke asks us to consider our mental contents while we look at the sun (I hope he knew not to look directly at the sun!) at T1 and contrast them with our mental contents at T2 when we recall looking at the sun back at T1. He tells us that if we do so we will “as plainly find the difference there is between any Idea revived in our minds by our own Memory, and actually coming into our Minds by our Senses, as we do between any two distinct Ideas” (IV.ii.14). That is to say, the difference between our mental contents at T1 and T2 will be as evident as the difference between two unrelated ideas. His conviction leads one to wonder why, if the difference is so obvious, doesn't he explain that in which it consists?
      In IV. xi. 5, Locke offers a possible criterion by which we can distinguish both types of havingE ideas. The “manifest difference difference” between the Ideas “laid up in my memory” and those that are the result of sensory perception is that the latter type “force themselves upon me” and “I cannot avoid having” them. So, if we cannot avoid havingE an idea then we must be in the act of perceiving through the senses; and if we can “at pleasure” have the ideas of the scent and colour or a rose, for example, then we are havingE an idea of something we previously sensed.
      But does this distinction always hold? One objection to this distinction is to question the passive-active dichotomy. When Locke speaks of ideas “forcing themselves upon” him the implication is that in perception we are passive agents; however, this it not true. Obviously, I have some control over whence I direct my sensory organs but Locke easily meets this challenge. He can simply reply that while we may be able to chose whence we direct our sensory organs, there is no way for me to “unperceive” the ideas that have been produced though sensory perception; and it is in this respect that we are passive. 
       This is certainly true in some instances but perceptual psychology has demonstrated that we are often blind to sensory objects to which we do not consciously attend. 

 Before reading further click on the link and do the selective attention test:

The classic demonstration of this phenomena is observed in an experiment where the subject is asked to watch a video in which two groups of players—half wearing white, half wearing black—pass multiple basketballs between themselves. The ostensible task of the subject is to count the passes the white team makes. Since the subject is attending so strongly to their task, after watching the video when they are asked if they noticed anything unusual they do not report noticing a man in a gorilla suit that strolled right across the screen, despite the fact that he was in their visual field. The upshot of the experiment is that at least to some degree in perception we are not totally passive; if this were true subjects would notice the man in the gorilla suit.
      We do not always recall things “at our pleasure” is the other objection to Locke's distinction between how the two ways we come to haveE ideas in our minds is that . There are two related counter-examples to this assertion. The first is demonstrated by the impossible challenge of not thinking of monkeys when someone commands “don't think of monkeys”. If we interpret Locke in the strong sense of our being able to access ideas from our memory at our pleasure—that is we have total control of what we access--then we'd expect to be able to not think about monkeys when commanded not to do so! But, as most of us learned when we first encountered this paradoxical command, it one with which it is nearly impossible to comply. In fact, I would be willing to wager that at this moment the reader is vainly trying to block out images of monkeys!
      There are other instances where we have limited control over our thoughts, and in these case the ideas "force themselves" from within. Consider situations when you get a song stuck in your head—what's worse is that it's usually a song that you can't stand. Perhaps this is only anecdotal but it certainly seems like the harder I try to expunge the offending tune from my mind, the more entrenched it becomes. Certainly, I did not recall the idea of this song “at my pleasure”! Nightmares are another example of the lack of control we have over what ideas appear in our mind--for even after we wake up our attempts to will away the disturbing images from our minds are futile.
      One could argue that these counter examples do not entirely discredit Locke's position that there is an obvious difference between ideas produced through perception and accessing ideas that were “layed up” in the memory; however, I think that while we can maintain a distinction, to call it an obvious distinction is to overstate the case. What the above examples have demonstrated is that resting the distinction on the passive-active criteria does not apply to all cases.   I think Locke is correct in his premise that there is a distinction between havingE and idea as produced through sensory perception and havingE an idea as a recalling of a prior experience but I'm not sure that the criterion by which he distinguishes the two does the work he needs it too.  How should Locke make this distinction? Can we find a better way within his own work?