Philosophy Discussion Forums

Can someone check this to see if it follows:

p1) I know p is false.
p2) I can not then know p is true. (by contradiction of p1)
p3) Knowledge is a subset of belief.
p4) If can not know p is true, then I can not believe p is true (p3,p2)
p5) if can not believe p is true, then i do not believe p.

Conclusion: I do not believe p is true

In p3 you assert that knowledge is a subset of belief. Therefore there are some members of "belief" that are not members of "knowledge". Therefore it is possible to believe something without knowing it. Therefore p4 does not follow from p1 to p3. You can believe that p is true even if you don't know that it's true; even if you know that it is false (p1). Therefore your conclusion doesn't follow from your premises. Premise p3 allows you to believe whatever you like.

telnaria wrote: ↑June 25th, 2018, 11:44 am Can someone check this to see if it follows:

p1) I know p is false.
p2) I can not then know p is true. (by contradiction of p1)
p3) Knowledge is a subset of belief.
p4) If can not know p is true, then I can not believe p is true (p3,p2)
p5) if can not believe p is true, then i do not believe p.

Conclusion: I do not believe p is true

If knowledge is true belief, and we define
s: I believe p is false
t: p is false,
then s&t is true only if s is true.

Is it true that s will be true regardless of t

telnaria wrote: ↑June 26th, 2018, 9:58 pm Is it true that s will be true regardless of t

If you know p is false, you also believe p is false, but you may believe p is false or true whatever the truth value of p.

Note that if you believe p is false, and p is false, that does not necessarily mean you know p is false, because it can only happen by chance that your belief is true. The famous definition of truth is "justified true belief", but in fact the situation is even more complicated.

telnaria wrote: ↑June 25th, 2018, 11:44 am Can someone check this to see if it follows:

p1) I know p is false.
p2) I can not then know p is true. (by contradiction of p1)
p3) Knowledge is a subset of belief.
p4) If can not know p is true, then I can not believe p is true (p3,p2)
p5) if can not believe p is true, then i do not believe p.

Conclusion: I do not believe p is true

p2 is a false conclusion. The correct one is "I know p is not true."
p4 is also false. "Peter I believed married Mary". I have no clue if this is true; I don't even know Peter and Mary. But I am at a liberty to believe Peter married Mary. Nothing contradictory about that.
p5 is a semantic truism. "I can't do x therefore I do not do x". It has nothing to do with the foregoing.

To give teeth to this example, substitute a truism for p, such as "I am Peter and I am not Peter." This you know to be false. For sure. NO arguments can be brought up to prove this to be true.
Can you then not know p is true? Of course you can. P is not true. YOU KNOW P is not true.

The entire argument is fragmented, full of false conclusions, and disparate, incongruent logical connections.

telnaria wrote: ↑June 25th, 2018, 11:44 am Can someone check this to see if it follows:

p1) I know p is false.

Conclusion: I do not believe p is true

Streamlined it for you.

Thank you alias. Much better.

If you have two contrary premises you’ll end up with a contrary conclusion.

May as well have said something like:

P1) p cannot be q
P2) p can be q

Conclusion is that this is a contradiction.

So if you start by saying “I know p is false” when in logic the tendency is to simple say “p is false.” Then you go on to say “knowledge is a subset of belief” without any explantion, yet trying to tag this “knowledge” onto the proposition of “true/false.”

Really are you simply saying if p is p, then p is p? No argument there.

P3 is setting out the idea of belief prior to knowledge, but you fail to note that knowledge can precede belief too. Again an endless circle (not that you’ve taken the time to define either - hence the hodgepodge of P4 and P5)

Recognise the use of belief and believe, and the use of knowledge and know. They are obviously related yet they are not always working within the same frame depending on the context they are applied in.

You may find it useful to employ other terms such as “apodictic knowledge,” “scientific fact”, “logical truth/validity/contradiction”, and such. At the moment it looks like you’re conflating several different approaches and coming up with a rather confusing and messy approach to presentig a logical proposition (not that I’m an expert!)

I think what Alias says is essentially how it goes. To be precise:

If believing is an essential part of knowing, then if I know p is false, I also believe p is false, and therefore (1) I cannot know p is true and (2) I cannot believe p is true. But (2) does not follow from (1).

A clarifying example: If there are no unicorns, I cannot know there are unicorns, but I can believe there are unicorns. But if I know there are no unicorns, I cannot believe there are unicorns.

If the premise is “Unicorns exist” then it is true that unicorns exist.

That is how logic works. Alias is correct to the extend he tried to point out that premises in logic need not be true or believed, they are what we determine truths from.

Don’t confuse logic with reality.

Example:

P1) If it is raining I will turn into a pumpkin.
P2) It is raining.

Conclusion: I have turned into a pumpkin.

The above is true if the logic is followed through. The OP is suffering from a lack of semantic distinction. I can say Alias doesn’t exist because “Alias” is not that persons name therefore if the name is false then “Alias” is not a person and doesn’t exist (in that strict sense.)

I am no expert on logic. It’s a very tricky and delicate business to learn the machinations of it. I’ve tried a little, but find it difficult to shake loose from concepts of arithmetic when it comes to combining and moving things around.

Burning ghost wrote: ↑June 28th, 2018, 10:58 am The OP is suffering from a lack of semantic distinction.

telnaria wrote: ↑June 25th, 2018, 11:44 am p1) I know p is false.
p2) I can not then know p is true. (by contradiction of p1)
p3) Knowledge is a subset of belief.
p4) If can not know p is true, then I can not believe p is true (p3,p2)
p5) if can not believe p is true, then i do not believe p.

Conclusion: I do not believe p is true

I see no problem with semantics. The only problem is that the conclusion does not follow from p3 and p2, but from p1 and p3: I know p is false -> I believe p is false -> I do not believe p is true.

P3 says “knowledge” is a kind of “belief” doesn’t it?