In the first case you are basing your belief on a capacity that within certain parameters (that is, in the right sort of environment) is an extremely reliable tree-detector (meaning it can detect real trees as opposed to fake trees, but not real trees as opposed to extremely vivid hallucinations). — Fafner
I didn't say that having this sort of capacity is sufficient for knowledge, that's a different question. Obviously you have to be responsive in the right sort of way to the deliverances of you perception - I agree that not all instances of e.g. directly seeing a tree (de re) are instances of knowledge, but I don't see the relevancy here. — Fafner
The relevance is that simply having a veridical experience isn't enough to claim that one has knowledge of the external world. You need the periphery understanding that your experience is veridical, but that kind of understanding is impossible (according to the sceptic). — Michael
Again, we've been over this already. I don't know what you mean by "knowing that your experience is veridical". As it stands it just means nothing, and so it is no objection. — Fafner
If you don't know that the tree you see is an external world tree then you don't know that there's an external world tree, even if the tree you see is an external world tree. Just as if I don't know that the blond woman I see is your mother then I don't know that your mother is blond, even if the blond woman I see is your mother. — Michael
It means knowing that the tree you see isn't just in your head. That you're not dreaming or imagining or a brain in a vat or being deceived by an evil demon. — Michael
You just repeated the world "know" here, but I asked what are the relevant requirements (according to the skeptic) for knowing such a thing? — Fafner
Recognising some evidence as ruling out the possibility that you're wrong, as per your opening post. If I can't recognise some evidence as ruling out the possibility that the tree I see is just in my head – that I'm a brain in a vat or being deceived by an evil demon – then I don't know that the tree I see isn't just in my head. — Michael
You have to distinguish between two senses of recognizing your evidence: a. knowing that if you have evidence of type E then you cannot be a brain in a vat and b. infallibly knowing that you indeed have evidence E and not merely seeming to have them. I agree that knowing (a) is necessary for knowledge, but not knowing (b). — Fafner
I know that if I have evidence that you have a sibling then you cannot be an only child. That doesn't mean that I know that you're not an only child. I need to actually have such evidence and recognise it for what it is. If I meet your brother but don't know that he's your brother then I don't know that you're not an only child. — Michael
Your conditional account of knowledge doesn't work. You need to actually have such evidence and recognise it for what it is. The problem is in recognising the evidence for what it is. How you do recognise that the experience you have is evidence that you're not a brain in a vat? The sceptic claims we can't. — Michael
I don't see how you can make this conclusion. A person in a waking state may have poor eyes, poor judgement, or be hallucinating when thinking that they are in a state of perceiving a tree. — Metaphysician Undercover
You seem to be neglecting the fact that evidence must be judged. The person must judge the perceptual evidence, as well as the meaning of the statement "that is a tree", in order to know that that is a tree. Human judgements can be mistaken. Therefore the person can be wrong. — Metaphysician Undercover
So here you use "objectively entail" to refer to the judgement which must be made. How do you ensure that the human judgement is not mistaken? — Metaphysician Undercover
I meant to exclude such cases, of course there are many ceteris paribus conditions that we must take into account. I meant that when you perceive a tree (you are not dreaming, your eyesight is normal etc.) then your perceptual state is correlated with the fact that there's a tree in front of you, and this is an objective matter. This is what should be properly regarded as your evidence. — Fafner
No, it doesn't refer to my judgment. You know that p, if you judge that p on a basis of evidence which entails that p (and p is true). Such judgments are fallible as you say, but it doesn't show that they are not knowledge when they do succeeded. — Fafner
My point, is that the evidence, your perception of a tree, never provides the basis for a conclusion which beyond the possibility of doubt. If you exclude all the cases in which you were wrong, i.e. it turned out to be a shrub or something like that and not a tree, to support your claim that the judgement is beyond doubt, then you are being unrealistic. — Metaphysician Undercover
Since "knowledge" as you use it refers to a successful judgement, and you have no way of knowing whether your judgement is successful or not, because you acknowledge that your judgement is fallible, then you have no way of knowing whether your judgements are knowledge or not. Therefore you should doubt all your knowledge. — Metaphysician Undercover
If we just stop being obsessive about absolute certainty, and adopt some more modest standards for knowledge claims (which is not the same as not having standards at all), then there will remain no longer any good reason to worry about what the skeptic is saying, and thus no reason to not to be confident in most of our claims to know. — Fafner
The underlined portion of the quote is exactly what the (philosophical) skeptic is saying: that there is no absolute certainty, knowledge, or truth that we can apprehend, only optimal approximations of absolute certainty, absolute knowledge, or absolute truth - which is not the same as not having standards at all. — javra
No, he doesn't say that - rather he's saying that there's no such thing as knowledge of the external world as such. — Fafner
To found my statements in fact, both Plato and Hume held that there is an external world. Both were staunch philosophical skeptics, rather than parodies of what philosophical skepticism entails. — javra
It depends on what one means here by "evidence". On my understanding, having evidence for p is being in a state of such kind that you cannot be in this very same state when p is false. — Fafner
The skeptic says that our confidence in all of our claims to knowledge ought to be 0, since there are some crazy possibilities of error that we cannot rule out. But does it follow? I think not. — Fafner
Now, suppose that you form a belief that there's a tree in front of you on the basis of your experience. Is your belief entirely without grounds as the skeptic claims? — Fafner
I don't think so, because the experience that you are having does rule out objectively, some possibilities of error - e.g., that you are looking at a traffic light or a painting of a tree etc.- since it is impossible for a person with a normal eyesight and proper lighting conditions to take a painting or a traffic light for a real tree. — Fafner
So in pother words, what I'm trying to argue is that we have good grounds to trust our judgments (and take them to be knowledge) even in the face of their fallibility, since it is simply not the case that they are completely groundless. Why should we assess our judgments relative to the imaginary stories that the skeptic tells us? If we just stop being obsessive about absolute certainty, and adopt some more modest standards for knowledge claims (which is not the same as not having standards at all), then there will remain no longer any good reason to worry about what the skeptic is saying, and thus no reason to not to be confident in most of our claims to know. — Fafner
See the conclusion of the skeptical argument in my first post. — Fafner
That's a ridiculous definition of "evidence". Evidence supports a belief it does not render it impossible that the belief is false. That's why to convince someone of something it usually requires more than one piece of evidence. If evidence for a belief rendered the belief necessarily true, then all that would be required would be one piece of flimsy evidence and the belief would necessarily be true. — Metaphysician Undercover
I think you misunderstand skepticism. The skeptic doesn't claim that our confidence ought to be zero, the skeptic claims that the confidence cannot be one hundred percent. And, since we cannot have absolute, one hundred percent confidence in any claim of knowledge, all knowledge ought to be doubted. — Metaphysician Undercover
Again, I think you misrepresent skepticism. The skeptic does not think that the belief is entirely without grounds, the skeptic thinks that the grounds for the belief ought to be examined. — Metaphysician Undercover
But very often people mistake shrubs for trees, and trees for shrubs. It is a common mistake. A small tree might be mistook for a shrub, and a shrub might be mistook for a small tree. How do you rule out this possibility for error unless you know that the person is adept in this type of judgement? — Metaphysician Undercover
Skepticism is not a claim that knowledge is "completely groundless". It is the claim that the grounds are just as likely to be mistaken as anything else is. — Metaphysician Undercover
What would be the point in lowering the standards for knowledge? You seem to think that this would get rid of the skeptic, but actually the reverse is true. If the standards are lowered, we can say P is knowledge when we have a lower degree of certainty of P. This means more cases of what is called knowledge turning out to be false, giving us more reason to be skeptical of anything which is called knowledge. — Metaphysician Undercover
The argument concludes "no p can be known". It defines "know" as ruling out the possibility of error, in premise 1. The argument says nothing about degrees of confidence in one's belief. The skeptic doesn't say, as you claim, that we can have zero confidence, the skeptic says that if "knowing" requires ruling out the possibility of error, as per premise 1, then we cannot know anything. This does not say that we cannot have any confidence in our beliefs. It says something about the nature of "knowing". — Metaphysician Undercover
What is crucial is that for something to be 'evidence' it must be intimately correlated with the facts that it is evidence for. — Fafner
If your grounds for claiming that you know something don't justify you to say that you know, then I think it comes down to the same thing as saying that you don't have any good reasons at all to say that you know (and hence you ought not to have any confidence in your knowledge whatsoever). — Fafner
The structure of the skeptical argument is such that all of your claims to knowledge are completely worthless unless you've ruled out all possibilities of error. — Fafner
Obviously the skeptics' argument is based on the idea that you can't say that you know something unless you are not absolutely sure that you are not mistaken - and of course this is the assumption that I'm rejecting. — Fafner
No, evidence is apprehended as being correlated with the belief which it is evidence for. So you have two things wrong here. First, the thing which the evidence is evidence of, is a belief it is not a fact. It cannot be called a fact, because the purpose of evidence is to convince someone of something which may or may not be true. Second, in order for it to be called evidence, it need not be intimately related to the belief, it needs only to be perceived as such. This is what makes it evidence of the thing, the fact that it is perceived as being related to the thing, whether or not it actually is, is irrelevant. — Metaphysician Undercover
No, evidence is apprehended as being correlated with the belief which it is evidence for. So you have two things wrong here. First, the thing which the evidence is evidence of, is a belief it is not a fact. It cannot be called a fact, because the purpose of evidence is to convince someone of something which may or may not be true. Second, in order for it to be called evidence, it need not be intimately related to the belief, it needs only to be perceived as such. This is what makes it evidence of the thing, the fact that it is perceived as being related to the thing, whether or not it actually is, is irrelevant. — Metaphysician Undercover
This doesn't make any sense to me. You seem to be using "justify" in a strange way. We often claim to know something when someone we trust has told us that. But this is not at all a form of justification. So we often claim to know something, and have a reason for making such a claim, yet that reason doesn't constitute justification. — Metaphysician Undercover
I've already told you, as well as javra has told you, that this is a misrepresentation of skepticism. In my last post, I clearly pointed out, in your own argument, how what you say here is not true to your argument. — Metaphysician Undercover
The argument, as you presented it, is that if knowing something requires absolute certainty, then we do not know anything. It does not say that you cannot know anything unless you are absolutely certain. — Metaphysician Undercover
2. Waking experience is indistinguishable from a very vivid dream (or a deception by an evil demon, or being a brain in a vat etc. – insert here your favorite skeptical scenario), since there are no distinct "marks" to distinguish the one from the other. — Fafner
It only begs-the-question if you believe that propositions like "I live on the earth" or "I am a person," need some kind of justification — Sam26
At some point it just doesn't make sense to epistemically doubt that there is no difference between, for example, dreams and waking states.
There is something very fundamental about our perceptions that's generally grounded for us, i.e., we generally accept them as veridical without the need for justification.
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