Consider the case of Peter the student. Peter knows that modus ponens is a valid inference rule in classical logic. He knows this because he has read it in his logic textbook and heard it from his logic teacher who is a professor of philosophy.

Can he know this even if he does not know the meaning of the terms "modus ponens" and "inference rule"?

What does "this" refer to?

Can he know this even if he does not know the meaning of the terms "modus ponens" and "inference rule"?

If he knows that the premises P, and if P then Q, entail the conclusion Q, then I don't think it would be incorrect to say that he knows that modus ponens is a valid inference rule.

How does he know that he does not know what the sufficient conditions of knowledge are if he does not know the sufficient conditions of knowledge? How does he know that he does not know without knowing he knows?

Please, no outrage. Maybe it makes me smile, but I really want to know.

Thank you for your post. What I meant was: Does he know that modus ponens is a valid inference rule if he understands neither the terms "modus ponens" and "inference rule" nor the fact that "the premises P, and if P then Q, entail the conclusion Q"? Does he know it merely because (a) it is true, (b) he is justified in believing it, having heard it from an authoritative source, and (c) he believes it on that basis?

He knows this because he has read it in his logic textbook and heard it from his logic teacher who is a professor of philosophy.

My inclination is to say that S does know that Qomolangma is the highest mountain in the world, reasoning as follows:
Premises
S knows Everest is the highest mountain in the world.
Everest = 'Qomolangma'

Conclusion
S knows Qomolangma is the highest mountain in the world.

If the above deduction is correct, what about the following?

1. S knows that every statement in his geography textbook is correct. (His well-qualified geography teacher has told him: "I have checked this book carefully, and everything in it is correct". The teacher is right, and S believes him.)

2. One of the statements in the textbook is that Quito is the capital of Ecuador.

3. Therefore, S knows that Quito is the capital of Ecuador, even if he has never heard of Quito or Ecuador.

This doesn't seem right to me. What do you think?

His belief that the geography textbook is without flaw, does not entail that he believes Quito is the capital of Ecuador. How would he believe that Quito is the capital of Ecuador, if he does not know what Quito or Ecuador are?

My believing that a textbook is reliable does mean that I know everything in said textbook, does it?

Peter also believes that he knows that modus ponens is a valid inference rule in classical logic. He is justified in his belief because the teacher has told him that he knows, and because the teacher is a very good authority for such a claim. It is also true that he knows that modus ponens is a valid inference rule in classical logic. Thus, he knows that he knows that modus ponens is a valid inference rule in classical logic. [Follows from the assumption of (∀P)(K(P)⇔(B(P)∧J(P)∧P))]

He is justified in his belief because the teacher has told him that he knows, and because the teacher is a very good authority for such a claim

Presumably he understands, to some extent, the terms "modus ponens" and "inference rule", after being lectured on them and studying them in a textbook, don't you think?

If he needs to understand (i.e. know the conditions for using) the terms "modus ponens" and "inference rule" (or some equivalent terminology) in order to know that modus ponens is a valid inference rule, why does he not need to know the conditions of knowledge (i.e. the conditions of using the word "knowledge" or an equivalent term) in order to know that he knows?

This demonstrates how one can know that they know, without knowing what knowledge is. Good!



And I think people will find this of most importance, as this is how he is justified in believing that he knows (which leads to him to knowing that he knows, since his belief is true).

So, it has been shown that it is possible someone can have a belief that they know something. It has been shown that this belief can be justified. And, lastly, it has been shown that this justified belief can be true. Never does knowing the conditions for knowledge come into play.

Thanks, Emil.

Now, does anyone wish to contest this?

If he needs to understand (i.e. know the conditions for using) the terms "modus ponens" and "inference rule" (or some equivalent terminology) in order to know that modus ponens is a valid inference rule, why does he not need to know the conditions of knowledge (i.e. the conditions of using the word "knowledge" or an equivalent term) in order to know that he knows?

I understand Emil's argument; I just want to resolve this apparent inconsistency.

One way is to contest that the justification given from the teacher about the student's knowledge is strong enough to warrant knowledge. Perhaps a general case could be made for that all appeals to authority are not strong enough to warrant knowledge.

By the way, the forum software now prevents me from seeing page three too. I would like to participate more but I cannot.

This seems as though it would put into question many things that we say we know. I know that water is composed of H2O, and I only know this from my science professors and research documents (which are also written by authorities).

Have you tried changing browsers?

Yes. But there may be limits for justification from authorities. I don't think there are so, but there may be. Someone could possibly argue it and be successful. (Note this word. Its spelling is particularly arbitrary. Double C and double S but no double L even though the word is normally spelled FULL!)

As long as we acknowledge that the authority isn't infallible, I don't see the problem. There are many things we are not experts on, and that we depend on authorities to know. We just have to take what we think we know from authorities with a grain of salt (like we should with most things we know!).

Seems like a solid justification to me. But again, as noted, we shouldn't believe the authority figure has epistemic certainty.

And, yeah, I don't understand why we spell "full" with two L's, but only use one L for the suffix "ful".

One way is to contest that the justification given from the teacher about the student's knowledge is strong enough to warrant knowledge. Perhaps a general case could be made for that all appeals to authority are not strong enough to warrant knowledge.

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That view would imply that if someone told me he had a headache, his authority would not be strong enough to warrant my knowing he has a headache.