Wednesday, October 31, 2012

Stanford encyclopedia of philosophy - fail

The problem with defining sense-data as "private, non-physical entities that actually have the immediately experienced sensory qualities" is that, to me, this is very obscure.
I have a bit of a general gripe with the authors that Stanford ask to contribute to their philosophical encyclopedia. They seem to me to fail properly to define the new terminology which they introduce, which surely is the key purpose of an encyclopedia.
The above definition says that a sense datum is an "entity". According to the OED, an entity is a being, a thing that has real existence. It seems confusing to define sense data as both non-physical and entities. Are they some form of metaphysical entity?
BonJour goes on:
"For a variant usage of this term, see Moore 1953, who there uses the term “sense-datum” to stand for whatever it is that is immediately experienced or given, possibly even a public physical object, and then argues somewhat tentatively that the entities that actually have this status are sense-data in the more usual sense, rather than physical objects.)"
Does that make any more sense? I am still struggling.
The Stanford article on 'Sense-Data' by Huemer suggests that they may be "mental images". The proposal that what we perceive are mental images is, to say the least, contentious.
The Huemer article goes on to try and give a "Stanford" view of what sense-data are (consistent with BonJour) as follows:
  1. Sense data are the kind of thing we are directly aware of in perception,
  2. Sense data are dependent on the mind, and
  3. Sense data have the properties that perceptually appear to us.
1. This distinguishes between direct and indirect perception, which is helpful but does not describe sense data.
2. Obvious (I think)
3. Meaningless
So I am still looking for a description of sense-data that actually describes what they are. The article proceeds to widen the definition as follows:
"The term “sense data” has not always been used in the sense described above. Indeed, when the term was first introduced by early 20th-century philosophers such as H. H. Price, G. E. Moore, and Bertrand Russell, it was intended only to denote that which we are directly aware of in perception."
But you will note we still don't know what they are. Isn't this a bit like saying "smells are what we smell" or "sounds are what we hear", it fails to provide a definition. The article then goes back to the original definition for the arguments for and against, which I think is a bit premature.

Indirect realism v naive realism

I have been challenged to articulate the argument for indirect realism, so thought I would post some further thoughts and some conclusions now I have completed the first perception module.

Indirect realism rests on the key fact that our perceptions are not the same as the object perceived. I would admit this as true in one sense, there is a conceptual difference between my perception of the stick and the stick itself.

Indirect realists believe that what we perceive is not the object, but sense data (or as Berkeley puts it "ideas"). Locke would argue that secondary qualities are ideas caused in us by the power of the object to produce those ideas. Indirect realists therefore argue that all we are aware of are mental representations. These mental representations act as intermediaries between the subject and the object being perceived. Since we cannot directly perceive the object, we have to infer its existence from the mental representations.

I am struggling to find a coherent and intelligible explanation of what a sense-datum is. Stanford encyclopedia says they are "mind-dependent objects that we are directly aware of in perception" but this doesn't offer any real kind of definition. I am afraid they remain very obscure from my perspective.

Having read some more arguments in favour and against indirect realism, I think I would have to classify myself as a naive realist. I feel that I have made a Moorean shift, and would want to argue from the belief that we do directly perceive the external world to a philosophical explanation of what we mean by this. To me it seems both self-evident and coherent that we directly perceive the external world, but I'm not sure which of the two justifications comes first.

We perceive things differently in different circumstances, but this seems to me to be consistent with a direct realist view. The stick appears bent under certain circumstances, i.e. we directly perceive the stick as it appears.

Talk of the stick appearing "as it really is" is, I believe, meaningless. The stick can only appear to us as it appears. The stick really is how we perceive the stick, assuming we are not suffering from a perceptual hallucination. It is a stick which appears bent under water and tiny when seen a long way away and red when seen in red light. We don't therefore perceive sense-data, we perceive the stick as it appears.

Monday, October 29, 2012

The argument from illusion contd.

I do not think that the argument from illusion is successful because it does not manage to convince me that there is a gap between appearance and reality.

In order to to establish a gap the argument would have to show that some things appear not as they should. We have already established that, using our cognitive faculties (including experience and reason), the stick should "appear" bent when under water and it does appear bent under water. In one important sense however, the stick does not appear bent - it appears how a straight stick should appear when under water, so in that important sense it appears straight.

I think the example of a tree seen in the distance is easier to grasp. The tree only appears small in one sense. It actually appears to be a tall tree seen at a distance, which is exactly what it is, a tall tree seen from a distance.

So, to pick up a challenge I issued earlier, does anyone have an example of any perception that does not match reality, once we have factored in human reasoning and experience? I am discounting hallucinations and optical / auditory illusions because we know that we can on occasions be deceived.

Saturday, October 27, 2012

Primary and secondary qualities

The distinction between the primary and secondary qualities of objects was an important theme within British empiricist philosophy, the three key proponents being John Locke, George Berkeley and David Hume.

Locke sets out the distinction in his 'Essay Concerning Human Understanding'. The distinction applies to the "simple" ideas we receive from sensation.

Primary qualities are properties objects have that are independent of any observer and include such properties as solidity, extension, motion, number and figure. They exist in the thing itself, can be determined with certainty, and do not rely on subjectivity. Secondary qualities are properties that produce sensations in the observer, such as colour, taste, smell, and sound. They are effects things have on people. Knowledge that comes from secondary qualities does not provide objective facts about things.

Locke argues that secondary qualities are somehow caused by the arrangements of matter, matter has the power to cause the ideas of secondary qualities. He believes that there is scientific support for his theory based on Boyle's new 'corpuscular hypothesis'.

Locke supports his theory by the use of examples. I will quote directly from Chapter VIII of Book II:
"Take a grain of wheat, divide it into two parts; each part has still solidity, extension, figure, and mobility: divide it again, and it retains still the same qualities; and so divide it on, till the parts become insensible; they must retain still each of them all those qualities. For division (which is all that a mill, or pestle, or any other body, does upon another, in reducing it to insensible parts) can never take away either solidity, extension, figure, or mobility from any body, but only makes two or more distinct separate masses of matter, of that which was but one before; all which distinct masses, reckoned as so many distinct bodies, after division, make a certain number. These I call original or primary qualities of body, which I think we may observe to produce simple ideas in us, viz. solidity, extension, figure, motion or rest, and number.

...Secondary qualities of bodies. Secondly, such qualities which in truth are nothing in the objects themselves but power to produce various sensations in us by their primary qualities, i.e. by the bulk, figure, texture, and motion of their insensible parts, as colours, sounds, tastes, &c. These I call secondary qualities. To these might be added a third sort, which are allowed to be barely powers; though they are as much real qualities in the subject as those which I, to comply with the common way of speaking, call qualities, but for distinction, secondary qualities. For the power in fire to produce a new colour, or consistency, in wax or clay,- by its primary qualities, is as much a quality in fire, as the power it has to produce in me a new idea or sensation of warmth or burning, which I felt not before,- by the same primary qualities, viz. the bulk, texture, and motion of its insensible parts."

Locke's theory of perception is a 'mediated theory of perception'. Accordingly, we do not have direct access to the world around us, but rather this access is mediated through our ideas.

Epistemic truth and fuzzy logic

In the context of the existence of the external world, two objections spring to mind to the contention that it is not a yes/no answer.

My first objection would be Kantian. I do not believe that is it possible for the external world to not exist. Human rationality pre-supposes the existence of space and time, it is the structure of rational thought. We can argue about what we mean by space and time, but the very fact that we can ask the question seems to me to presuppose the external world. If I were to summarise this argument I might say that nothing would "make sense" if the external world didn't exist.

My second objection would be that the logic behind the question seems to be bivalent, i.e. two-valued. I accept that we can have different senses of the word "exist", for example things can exist in fiction, or in conceptual terms. However, when we ask the question "does the external world exist?" this question deserves a yes or no answer. How could it be that the answer is that the external world sort of exists and at the same time sort of doesn't exist? That response, at least to me, is non-sensical.
Fuzzy logic seems to apply to non-bivalent questions, such as "are there 30ml of water in this glass?" I can see how this question has a non-bivalent answer because, in part it depends on how carefully you measure the contents of the glass. I also accept that the contents of the glass change over time through evaporation.

But you will note that by debating this we are pre-supposing the existence of the external world, or at least of space and time. In so doing we have knowledge that the external world (in terms of space and time) does exist.

The argument from illusion

The argument from illusion infers from the fact that we can sometimes be deceived by our perceptions (i.e. suffer from misapprehensions or illusions) that we do not directly perceive the external world.

The argument necessitates that our sense perceptions are "processed" by our minds and our cognitive faculties (in terms of information processing) have a significant role to play in our belief in and our awareness of the "external world".

My position is that the argument from illusion is flawed. It does not necessarily follow from the fact that we are sometimes deceived by our senses that we are always deceived by our senses. Even if it were the case that we cannot tell when we are being deceived (which I think is dubious) this would not mean that we cannot, sometimes, directly perceive the external world.

I would give the example of a camera with a random electronic fault. Sometimes the camera correctly captures an image, at other times it distorts the image so that all the colours are reversed. I do not believe that we would we conclude from the presence of the fault that the camera can never capture a true image, all we could conclude is that we would need to be careful about the images from that camera.

The example of a stick appearing bent under water is also not a good argument for lack of direct perception of the external world. Since we understand why the stick appears bent, I would have thought that the stick appearing straight under water would be a better argument for illusion. How should the stick appear? It should appear bent if we directly perceive the external world.
Similarly with the example of the oasis in the desert. Under the correct atmospheric and psychological conditions we would expect to see an oasis where there was not in fact one to see if we did in fact directly perceive the world.

I think a much stronger argument for illusion would be where someone does in fact see a "miracle", i.e. something which is known to be not of the real world. I am not aware of any such cases so the argument, in my view, fails.

frustrations with reliabilism / responsibilism


I'm struggling with this module, and looking forward to getting onto more familiar ground in the next section.

If we are trying to conclude whether the justification part of JTB is fundamentally an internalist or externalist process, then the answer is "that depends on what you mean by justification". Both views are helpful in suggesting different ways to look at what we can mean by justification, but we can use the term in different ways at different times. I think we agree that a purely internalist view has its problems, so does a purely externalist. On the whole I don't think we can "narrow down" the concept of justification to this degree.

On the whole I am not happy that the reliabilsm/responsibilism or internalism/externalism debate has much further to go. I also get frustrated when the texts mainly seem to accept that Gettier's argument was a good one, the more I think about it the more I would just reject his cases as being examples of JTB, and therefore dispense with a lot of worrying about adding additional criteria.

I also think the thermometer argument is very odd, and not really all that illuminating. I think I understand what it is trying to show, but would reject the fact that we can say that we have (high-standards) knowledge of the temperature in a room by looking at a thermometer which is normally reliable. We have to allow for the fact that the thermometer might be broken, and anyone who wanted to bet their life on the outcome would I think agree.

The chicken-sexer argument is a little more helpful, but all it really shows is that sometimes the justification we give for having knowledge is not in fact the real justification that we use. This doesn't seem to be a particularly ground-breaking point.

truth and probability

There is an epistemic difference between knowledge of the past/present and knowledge of the future. In the cases where we can predict the future with a high confidence level, I still don't think this would count as knowledge, mainly for the reason that any proposition which involves a prediction where there is a chance that it turns out to be false cannot be regarded as true (at the time it is made). think I agree with the basic JTB formulation, i.e. the proposition has to be true and justified at the time it is made.

I accept that some knowledge that we previously held to be true can subsequently turn out to be false, and I don't think that prevents the old knowledge from being classified as knowledge at the time, or means that we cannot in fact know anything.

I'm not inclined to adopt the approach of only really knowing things with a high degree of probability. For example, I don't think that it is only highly likely that the Earth orbits the Sun, I think this is 100% true. If, for some reason an alternative theory was proposed which negated the heliocentric view, then I would change my assessment at the time.

internalism / externalism

My interpretation would be that internalism is closer to responsibilism and externalism is closer to reliabilism.

It seems that some externalists might, however, argue that knowledge does not require justification, which would be contrary to a reliabilist approach.

If I think about the truth of propositional statements, I believe that the internalist/externalist distinction is not particularly helpful. The reason we seem to have two theories is that "knowledge" has different meaning in different circumstances, some of which lend themselves to an externalist definition and others an internalist. It isn't as straightforward as saying one view is correct and the other is false.

I also think this argument applies to responsibilism v reliabilism to a certain degree. We use the word knowledge in different ways in different circumstances, similar to the high standard / low standard debate.

In a high standard context, knowledge cannot be entirely subjective, be that either 'responsibilist' or 'internalist'. That seems contrary to the generally accepted meaning of knowledge. If a purely internalist definition could account for knowledge it would seem to underplay the role of society in validating knowledge.

Saturday, October 20, 2012

virtue epistemology

Virtue epistemology addresses the question of how we rationally justify knowledge. The way we justify knowledge is expressed in terms of intellectual or cognitive virtues, these virtues are normatively valuable, they warrant our approval.

By moving discussion about justification to a normative debate, virtue epistemologists reject a purely cognitive or positive approach to the problem of knowledge. Intellectual agents and groups of agents become the important source of epistemic value and therefore of knowledge justification, as opposed to reliance on, for example, sense perception or a priori truths.

There are a number of different schools of thought within virtue epistemology, the different approaches placing a greater or lesser emphasis on different cognitive or intellectual traits and epistemic norms.

Reliabilism concentrates on cognitive faculties which result in knowledge. Beliefs are warranted if they are formed by a process that generally produces true beliefs rather than false ones. A reliabilist approach tends to focus on the outcome of the process, if it is generally successful (reliable) then it is a good way to acquire to knowledge.

Responsibilism concentrates on intellectual character traits such as attentiveness, fair-mindedness, open-mindedness, intellectual tenacity, and courage. Responsibilists tend to concentrate on the approach taken by the agent to acquire knowledge. If the agent demonstrates laudable epistemic intellectual character traits then the result can be justified as knowledge.

For Sosa, intellectual virtue / virtue epistemology can be used as a way to reconcile or overcome the issues raised by Agrippa's trilemma. For example, virtue epistemology can overcome the objection to a purely coherentist approach where there could be a disconnect between a set of coherent beliefs and the external world.

Thursday, October 18, 2012

First Assignment

I have just submitted my first assignment, which was to write approximately 500 words on the nature of knowledge, paying attention to at least some of the following issues:
  • Why is there more to knowledge than merely true belief, or even justified true belief?
  • What is the structure of knowledge? More specifically, must knowledge be grounded in epistemic foundations?
  • What is the relationship between knowledge and rationality?
  • Why, if at all, is knowledge valuable?
This is my attempt:

The study of knowledge, ‘epistemology’, is an important philosophical field. I will address two  questions: ‘what is knowledge?’ and ‘what is the value of knowledge?’.

Three different types of knowledge can be identified. Firstly, the knowledge of how to do something (for example, I know how to tie a shoelace), this is called ‘ability’ knowledge. Secondly, we can have knowledge of people or places (for example, ‘I know Mr Smith’), this is referred to as ‘acquaintance’ knowledge. Thirdly, the kind that is of most relevance to philosophy, ‘propositional knowledge’ is the knowledge that something is the case (for example, it is the case that the Earth orbits the Sun).

What is the value of knowledge? Knowledge frequently has instrumental value in that it helps us to achieve an objective. For example, the knowledge of a street layout can help to plan the shortest route home. There is no settled philosophical consensus as to whether knowledge has intrinsic value, i.e. is valuable in itself. I regard intrinsic value as being dependant on a person’s value-system. It seems possible to attribute value to different virtues and it is therefore possible to regard knowledge (or wisdom) as virtuous. A more utilitarian view would reject this analysis and argue that value is only ultimately attributable to happiness; knowledge is instrumentally valuable if it contributes towards general happiness and has no intrinsic value.


Two philosophical approaches can be identified for investigating the problem of knowledge. Particularism asks what are the common features of all cases of knowledge. Methodism looks at the sources of knowledge and the methods by which it is obtained. Both approaches assume that we have knowledge in the first place and suffer from the problem of the criterion, whereby in order to take a particularist approach we presume we know the method to use and vice versa. The problem of the criterion has led some to tend towards scepticism.

A traditional definition of knowledge posits that three conditions are necessary for a subject to be regarded as knowing a meaningful proposition. Firstly, it is un-contentious that the proposition must be true and not false. We cannot ‘know’ something that is false, for example that the Sun orbits the Earth. Secondly, it is also generally un-contentious that the subject must believe that the proposition is true. Thirdly, it is often claimed that the subject must be justified in their true belief in the proposition. When combined together these three (‘JTB’) conditions may be regarded as necessary and sufficient for a definition of knowledge.

Edmund Gettier pointed out a potential shortcoming to the JTB definition by providing example cases in which the subject has justified true belief which has been obtained by luck, which do not count as knowledge. The most persuasive objection to Gettier’s cases is that the subject is not in fact justified in their belief in the examples given. If we accept that JTB is not sufficient, additional conditions can be formulated such as the absence of ‘knowledge defeaters’, also known as the defeasibility condition.

There are three key theories of justification for propositional knowledge, foundationalism, infinitism and coherentism. Agrippa’s trilemma points out that none seem to be entirely satisfactory. I suspect that we deploy all three sources of justification to different degrees in different circumstances.

Justification criteria have led to much philosophical discussion. It is widely accepted that to be epistemologically justified in holding a belief, the subject must have acquired the belief through a rational process. There is much debate as to how to define what makes a process ‘rational’, whether it depends only subjectively on the (responsible) process that has been followed (deontic epistemic rationality) or if it depends on compliance with epistemic norms which are objectively appropriate (non-deontic/ externalist rationality). My view is that non-deontic rationality more closely matches the process of acquiring propositional knowledge.

Tuesday, October 9, 2012

Truth, belief in God and Kant

Could you argue that the fact that 97% of people believe something is true makes it true? What if those 97% of people do not understand why their belief is wrong?

Pre-Copernicus, 97% of people believed that the the Sun revolves around the Earth. Was the geocentric view true and then became false or was it always false?

With regards the existence of God, using coherentism as justification fails because there needs to be some evidence if you are making a scientific claim and extraordinary claims require extraordinary evidence to support them.

The following link sets out some of Plantinga's arguments for the existence of God:
http://www.infidels.org/library/modern/alvin_plantinga/conflict.html

Evolutionary biologists would not contest the view that we are hard-wired to believe in God, it is indeed quite common at our current state of evolutionary development. But this does not make it true, in fact it supports the explanation for why so many of us believe in something which is untrue. Personally, I don't agree with Plantinga's arguments.

Kant has a different take on epistemology, which when you read it is very original and convinving.

Kant's argument for synthetic a priori truths is summarised well in the Internet Encyclopedia of Philosophy:
"Kant’s answer to the question is complicated, but his conclusion is that a number of synthetic a priori claims, like those from geometry and the natural sciences, are true because of the structure of the mind that knows them. “Every event must have a cause” cannot be proven by experience, but experience is impossible without it because it describes the way the mind must necessarily order its representations. We can understand Kant’s argument again by considering his predecessors. According to the Rationalist and Empiricist traditions, the mind is passive either because it finds itself possessing innate, well-formed ideas ready for analysis, or because it receives ideas of objects into a kind of empty theater, or blank slate. Kant’s crucial insight here is to argue that experience of a world as we have it is only possible if the mind provides a systematic structuring of its representations."

Monday, October 8, 2012

what is knowledge?

A few more thoughts on what we are doing when we do philosophy, particularly in the context of trying to describe/understand/define propositional knowledge.

There seem to be two key questions about knowledge:
1. What is knowledge?
2. What can we know (and conversely what can't we know)?

Question 2 gets into the realm of scepticism, which is coming up later in the course so I will hold my fire for now.

On question 1, so far in the discussion we have tried to define which characteristics of knowledge are both necessary and sufficient. We largely agree that for a proposition about the world to be counted as knowledge it has to be true belief. We then added the requirement for justification. We then saw that perhaps we can have justified true belief that does not count as knowledge and considered what else is necessary beyond JTB.

The justification arm of the definition seemed to me to be the most interesting at first. There are lots of theories about what counts as justification, I for one am reluctant to rule any of them out.
Discussions on epistemology are interesting because the very act of trying to define knowledge by necessity involves assessing and deploying the very concepts we are trying to define. We say things such as "knowledge requires justification for it to count as knowledge" but then someone could quite reasonably say "justify why knowledge requires justification". We seem to be trapped in some kind of loop. We are then struck with the is/ought reversal.

There are two main threads which I am beginning to see emerge from the conversations. My initial reaction to the question 'what is knowledge?' was that to be counted as knowledge, a proposition had to describe or somehow match something that is true about the world. This might tend us towards a foundationalist account. If knowledge is "fixed" then the role of the philosopher is not only to be very clear about the definition but to explain how it is fixed.

But we saw that what counts as knowledge changes over time. For me this tends us towards a coherentist account (which allows us to fix the leaks in the ship as we proceed) and also brings in normative considerations. We still need to be very clear about the definition, but we also need to consider what we ought to count as knowledge under different circumstances.

In laying down the rules we need to be logically consistent. An argument is not a proper argument if it's logically flawed. But what are the truths of logic truths of? Why is knowledge only knowledge if it is based on logically sound arguments? Is it just a question of being meaningful and playing by the rules (i.e. our language has to make sense) or is there some kind of transcendental truth which, amongst other things, makes logic logical.

So I have come back full circle and am now back considering what we mean by truth....

Saturday, October 6, 2012

coherentism v foundationalism v infinitism

On the whole I tend towards the coherentist explanation of knowledge. An item of knowledge that is 'coherent' to one person may not be to another, either because they have a wider/smaller circle of knowledge or because they place more weight on some beliefs than on others.

Coherentism would deny that there is foundational knowledge (such as the belief in the truth of a loving God) but I don't think it would deny that people have differently constructed belief systems. NB a coherentist could believe in God, but would not hold this as a foundational belief.

A foundational item of knowledge is held (justified true belief) without further support or appeal to other items of knowledge, either because it is innate (existing from birth) or self-evident. Descartes is a good example of a classical foundationalist because he traces his knowledge back to the foundation of the knowledge of his own existence. I think he would argue that this foundation is self evident, through the power of reason.

Coherentism would also deny infinitism, where the support for a particular item of knowledge is always another item of knowledge (ad infinitum).

The problem with foundationalism seems to me that it is impossible to identify and agree on foundational knowledge or to explain how we come by it. Self evidence isn't really a great argument since, as has already been pointed out it seems to assume quite a lot, to take quite a lot for granted.

Friday, October 5, 2012

Moorean shift

I have been struck when looking at some of the reading on knowledge that GE Moore yet again provides a very valuable insight into "common sense" approaches to philosophy. In my previous Introduction to Philosophy course I was taken by the "Moorean shift" response to scepticism, and again Moore expresses some important points on epistemology.

By common sense he doesn't just mean "what is commonly believed", it is a little more sophisticated....

Wikipedia explains the "common sense" response well;
"The method of common sense espoused by such philosophers as Thomas Reid and G. E. Moore points out that whenever we investigate anything at all, whenever we start thinking about some subject, we have to make assumptions. When one tries to support one’s assumptions with reasons, one must make yet more assumptions. Since it is inevitable that we will make some assumptions, why not assume those things that are most obvious: the matters of common sense that no one ever seriously doubts.
"Common sense" here does not mean old adages like "Chicken soup is good for colds" but statements about the background in which our experiences occur. Examples would be "Human beings typically have two eyes, two ears, two hands, two feet", or "The world has a ground and a sky" or "Plants and animals come in a wide variety of sizes and colors" or "I am conscious and alive right now". These are all the absolutely most obvious sorts of claims that one could possibly make; and, said Reid and Moore, these are the claims that make up common sense.
This view can be seen as either a version of foundationalism, with common sense statements taking the role of basic statements, or as a version of Coherentism. In this case, commonsense statements are statements that are so crucial to keeping the account coherent that they are all but impossible to deny.
If the method of common sense is correct, then philosophers may take the principles of common sense for granted. They do not need criteria in order to judge whether a proposition is true or not. They can also take some justifications for granted, according to common sense. They can get around Sextus' problem of the criterion because there is no infinite regress or circle of reasoning, because the buck stops with (see also idiom) the principles of common sense."

Gettier's criticism of justified true belief

On the whole I am impressed but not entirely convinced by the Gettier criticism of justified true belief (JTB) as a good definition for knowledge. It seems possible to define the justification criteria to exclude Gettier cases as being true knowledge, and that feels intuitively the right approach to take. I can't believe it is necessary to add lots of additional caveats or criteria to exclude Gettier cases from qualifying as knowledge, instead we need to be clearer about what we mean by justification.

I think perhaps Gettier examples are "reasonable assumptions" but not "knowledge".

So to be justified, knowledge needs to be based on reasoning that takes account of chance, luck, misapprehension, illusions etc. This is why Descartes came to the conclusion that there was only one bit of knowledge of which he could be entirely sure - the fact that he existed!

Of course the amount of justification required depends on the circumstances and the use to which the knowledge is being put. If someone asks you the time because the want to catch a train, the justification needed is less conclusive than if they need the time to calculate the longitude of a ship crossing the ocean.

So in conclusion there are certainly different standards by which we would assess propositions as being knowledge, and these standards vary significantly depending on the circumstances in which the statements are made.

the problem of the criterion

I find the problem of the criterion very interesting. My take on the problem is that we have a concept of "knowledge" which most people seem to understand. The question is how do we come to understand what we mean when we use the term "knowledge". Can we understand the meaning without resorting to instances?

When we develop language I think it is fair to say that basic concepts are "taught" by pointing to examples and saying "that is an example of x". The subject then begins to recognise what is common between all of the different instances and thereby how to use the term in meaningful language.
If we accept that there is a definition of knowledge which comprises several other concepts such as belief, truth and justification, then is it the case that our understanding of these concepts must precede our understanding of knowledge?

Could there in fact be a concept of knowledge which exists independently of any cases of knowledge or independently of language?

It does seem odd that we have a gut feeling that the term "knowledge" is something more than just a label.

I realise I am asking a lot more questions than I am answering!