## Can someone check this to see if it follows

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Burning ghost
Posts: 2797
Joined: February 27th, 2016, 3:10 am

### Re: Can someone check this to see if it follows

If so then P4 and P5 are identical.

Break this down into notion:

P1) - p (not p)

P2) reiteration of P1 so this is redundant.

P3) B is a subset of A.

P4) -p -> -p (basically this is P1)

P5) reiteration of P4.

That’s it. Nothing more is there?

Tamminen
Posts: 723
Joined: April 19th, 2016, 2:53 pm

### Re: Can someone check this to see if it follows

Burning ghost wrote:
June 28th, 2018, 1:48 pm
If so then P4 and P5 are identical.

Break this down into notion:

P1) - p (not p)

P2) reiteration of P1 so this is redundant.

P3) B is a subset of A.

P4) -p -> -p (basically this is P1)

P5) reiteration of P4.

That’s it. Nothing more is there?
It is about the logic of knowing and believing, based on the definition of knowledge, which can be "justified true belief" or something added to this definition. Alias said the core of what the OP tried to say: if I know p is false, I cannot believe p is true. But p4 is not right, and p5 adds no information.

Burning ghost
Posts: 2797
Joined: February 27th, 2016, 3:10 am

### Re: Can someone check this to see if it follows

So if I know x is false then x cannot be true.

p->q where p is the statement “I know x is false”, and q is the statement “x cannot be true.”

Note: (p->q) <=> (-p v q) which means “I know x is not false (ergo true) OR x cannot be true.”

The OP states “contradiction” but there is no contradiction just a lack of understanding of how to apply logic to sentences.

Tamminen
Posts: 723
Joined: April 19th, 2016, 2:53 pm

### Re: Can someone check this to see if it follows

Burning ghost wrote:
June 28th, 2018, 3:39 pm
So if I know x is false then x cannot be true.
That is right, but also "If I know x is false, I cannot know x is true" and "If I know x is false, I cannot believe x is true", which were the sentences in the OP.
Burning ghost wrote:
June 28th, 2018, 3:39 pm
p->q where p is the statement “I know x is false”, and q is the statement “x cannot be true.”

Note: (p->q) <=> (-p v q) which means “I know x is not false (ergo true) OR x cannot be true.”
(-p v q) means "Either I do not know that x is false OR x cannot be true". But this was not the sentence of the OP.

Burning ghost
Posts: 2797
Joined: February 27th, 2016, 3:10 am

### Re: Can someone check this to see if it follows

Tam -
(-p v q) means "Either I do not know that x is false OR x cannot be true". But this was not the sentence of the OP.
They are equivalent that is what the <=> means.

To see this simply apply a more tangible sentence.

IF I am alive THEN I am not dead” is equivalent to saying “I am not alive OR I am not dead.” (They are the same.)

Tamminen
Posts: 723
Joined: April 19th, 2016, 2:53 pm

### Re: Can someone check this to see if it follows

Burning ghost wrote:
June 28th, 2018, 10:00 pm
Tam -
(-p v q) means "Either I do not know that x is false OR x cannot be true". But this was not the sentence of the OP.
They are equivalent that is what the <=> means.

To see this simply apply a more tangible sentence.

IF I am alive THEN I am not dead” is equivalent to saying “I am not alive OR I am not dead.” (They are the same.)
I know, but your description of it was not right. Compare your version with mine above.

Burning ghost
Posts: 2797
Joined: February 27th, 2016, 3:10 am

### Re: Can someone check this to see if it follows

The “know” doesn’t come into it as far as I can see. It says x is false, so I alter it to x is not false.

I say this because if I say “I know x” it different from saying “x is x.” So to say “I know x is false” is just to state “x is false” the negation of which leaves us with “x is not false,” not “I don’t know x.”

There was a reason I brought up semnatics. Many sentences need cutting up carefully before moving ahead with the logic. I am well within my right to say what I’ve said. I am not wrong, “knowing” has very little to do with it

If I am wrong I am wrong.

Does the sentence “I know x is false” not alter at all? doesn’t it say simply “x is false.” ??

Tamminen
Posts: 723
Joined: April 19th, 2016, 2:53 pm

### Re: Can someone check this to see if it follows

Burning ghost wrote:
June 29th, 2018, 6:32 am
Does the sentence “I know x is false” not alter at all? doesn’t it say simply “x is false.” ??
There is a big difference.

If x is false, I need not know x is false, and I can believe x is true.
If I know x is false, x is false, and I cannot believe x is true.

This was the problem with the OP, although its conclusion was right.

Burning ghost
Posts: 2797
Joined: February 27th, 2016, 3:10 am

### Re: Can someone check this to see if it follows

That makes no sense to me whatsoever.

The OP made more sense than that, but I understood it was based on strange definitions of “belief” and “knowledge.”

Oh! Just got it. Again, the issue is with the “know” and “belief.”

For dumbos like me it is best to say:

P1) x is false.

P2) I know x is false.

P3) knowledge a subset of belief.

Then using P2 proceed.

Tamminen
Posts: 723
Joined: April 19th, 2016, 2:53 pm

### Re: Can someone check this to see if it follows

Burning ghost wrote:
June 29th, 2018, 9:02 am
That makes no sense to me whatsoever.

The OP made more sense than that, but I understood it was based on strange definitions of “belief” and “knowledge.”

Oh! Just got it. Again, the issue is with the “know” and “belief.”

For dumbos like me it is best to say:

P1) x is false.

P2) I know x is false.

P3) knowledge a subset of belief.

Then using P2 proceed.
Right. But why did my previous post not make sense?

Burning ghost
Posts: 2797
Joined: February 27th, 2016, 3:10 am

### Re: Can someone check this to see if it follows

It did ... that is why I said “Oh! Just got it.” I was slow on the uptake is all.