## What can I know with 100% certainty?

• 692
I agree with everything you have said except for this statement: "And see, you are bringing it up yourself, invalidating therefore your first statement, i.e. that you are 100% certain that you are conscious!" My statement: "It is possible that what I perceive is either a dream or a hallucination or an illusion or a simulation and not objectively real." does not invalidate my previous statement: "I am 100% certain that I am conscious." My experience of being conscious makes me 100% certain that I am conscious when I am conscious. I don't experience this when I am unconscious. It is possible that my perceptions e.g. I see the computer keyboard and the computer screen as I type these words, are not of an actual reality. It's possible that the keyboard and the screen exist only in a dream or hallucination or simulation or illusion.

You said that you lost the ball when I mentioned macroscopic determinism. So, I will explain it. Quantum indeterminacy https://en.wikipedia.org/wiki/Quantum_indeterminacy and the Uncertainty Principle https://en.wikipedia.org/wiki/Uncertainty_principle exist. However, this does not lead to indeterminacy at the macroscopic level. We can precisely measure the position and vector of a football even though we can't do that with an electron.

I agree that our perceptions of reality is subjective but there is such a thing as shared subjectivity e.g. we can both see the Sun and the Moon. So, the Sun and the Moon exist in our shared subjective world. Most humans would say that the existence of the Sun and the Moon is an objective truth because every human with a functioning visual system sees the Sun and the Moon when they are visible.
• 2.1k
My statement: "It is possible that what I perceive is either a dream or a hallucination or an illusion or a simulation and not objectively real." does not invalidate my previous statement: "I am 100% certain that I am conscious." My experience of being conscious makes me 100% certain that I am conscious when I am conscious. I don't experience this when I am unconscious.
You mean, when you are conscious, you are conscious indeed. But how do you know that you are not dreaming or hallucinating? You may be dreaming or hallucinating at any time. And you wouldn't know it if you are.
But this is stretching the point a little too much. Let's simplify it and assume simply that you are indeed able to know that you are conscious. This is more pragmatic. Otherwise, we would be living in a consctant doubt!
So, OK, I agree with your statement that you are 100% certain when you are.

About quantum indeterminacy, etc. I'm not quite knowledgeable in this area. Physics are not my strong point. Yet, I know a few things, like Heisenberg's uncertainty principle, which reinforces the position that we cannot be 100% certain for anything. Although, I don't know in which cases and how microcosm agrees with macrocosm ...

there is such a thing as shared subjectivity e.g. we can both see the Sun and the Moon. So, the Sun and the Moon exist in our shared subjective world. Most humans would say that the existence of the Sun and the Moon is an objective truth because every human with a functioning visual system sees the Sun and the Moon when they are visible.
"Shared subjectivity" ... Interesting expression. Never met it or thought about it. I personally use the expression "shared reality". But I agree with the way you described it.
It's good that you brought up this point, since a shared reality is an agreement about something, a common viewpoint, etc. And this is where I use to say, that common reality is the closest we can get to absolute reality. The more a reality or agreement about something is common among people, the more solid that reality is. And this is good enough. We don't need more. :smile:

BTW, its's interesting to see that the above apply also to the individual him/herself. The conflicts in us that we are experiencing, are disagreements between different thoughts or ideas in our mind. They act as opposing forces fighting with each other. And on the contrary, lack of conflicts make for calm and harmony. In such cases, our reality is more solid and we are closer to 100% certainty. :smile:
• 23.7k
As mentioned a few times in other threads, here's an odd logic:

Premise: We don't know anything with 100%, absolute, undeniable certainty.
Conclusion: Therefore, we don't know anything.

Of course, no one would actually suggest such an inept argument...
• 692
I am not saying this at all. On the second last post on page three of this thread, I have stated that I know 7 things with 100% certainty.
• 692
Being conscious is a prerequisite for experiencing dream or hallucination or illusion or simulation. That's why I can be 100% certain that I am conscious whether or not my perceptions of reality (e.g. my body, other organisms, the Earth, the rest of the Universe) are of an actual reality or not.

I created the term "shared subjectivity". It is more accurate than saying "shared reality" because we don't actually know with 100% certainty whether our perceptions of reality are of an actual reality or not.

What is true at the quantum level is not true at the macroscopic level. We can't measure both the position and vector of electrons but we can measure both the position and vector of footballs. Another example would be quantum superposition https://en.wikipedia.org/wiki/Quantum_superposition This never happens at the macroscopic level. When one tosses a coin, it does not land on both the head and the tail at the same time. It lands on either the head or the tail.
• 2.1k

"Shared subjectivity" (quoted) gets 9,300 results in Google. "Shared reality" (quoted) 317,000. :strong:
:smile:
I didn't say that "shared subjectivity" is wrong, anyway ...

As for QM .... I pass. :smile:
• 692
Thank you for letting me know. I had never Googled shared subjectivity until I read your post. I came up with the concept many years ago when I was discussing reality with my friend.
• 626
Premise: We don't know anything with 100%, absolute, undeniable certainty.
Conclusion: Therefore, we don't know anything.

Of course, no one would actually suggest such an inept argument...

https://en.wikipedia.org/wiki/I_know_that_I_know_nothing
• 2.1k
• 692
Thank you for the interesting link.
• 692
Along with shared subjectivity, there is also exclusive subjectivity e.g. only I know the contents of my dreams and what thoughts and recollections occur to me.
• 23.7k
And?

I suggest you glance at the talk page.
• 442
100% certainty from whose perspective?

I can "know" with 100% certainty (from my perspective) that the world is flat.

However from the perspective of the International Space Station I'd be 0% accurate.
• 626
Banno
21.2k
↪PL Olcott And?

I suggest you glance at the talk page.

I agree with you, I merely referenced a very famous quote that seems to disagree with you.
We can at the very least know that existence exists right now.

Within the assumption that our memory is not fake we can also know everything that we are aware of that is proven to be completely true entirely on the basis of its meaning. We know that cats are animals.

While we are looking at a cat we can know that we are looking at a cat (as long as it is not a space alien perfectly disguised as a cat). This remains true even if all of actual reality is a mere figment of our own imagination.
• 23.7k
We can at the very least know that existence exists right now.

Rubbish. It's not at all clear what that might even mean. Use of ideas from Ayn Rand will only detract from your credibility.

I'll again leave you to it.
• 692
From my perspective. I agree that the world looks flat to me when I am at home on Earth but it won't look flat if I was on the International Space Station.
• 626
We can at the very least know that existence exists right now.
— PL Olcott

Rubbish. It's not at all clear what that might even mean. Use of ideas from Ayn Rand will only detract from your credibility.

I'll again leave you to it.

It is a paraphrase of: https://www.britannica.com/topic/cogito-ergo-sum
• 23.7k
No, it isn't.
• 626
Banno
21.2k
↪PL Olcott No, it isn't.

That is the way that I mean it.
If one is aware that one is thinking this proves that thinking exists.
If thinking exists then this refutes the assertion that nothing exists.
This is the most certain thing because it occurs RIGHT NOW.
• 626
↪PL Olcott Thank you for the interesting link.

I really appreciate all of your feedback. This whole forum seems filled with
people that are knowledgeable of the subject and sincerely want an honest dialogue.

Trying to talk to logicians about the foundations of truth and logic is like trying to
talk to atheists about God. I am very happy that I found this forum.
• 3k
You can have a true description of something that is nonetheless misleading due to its lack of detail. E.g., "North Korea invaded South Korea because of Acheson"s equivocal response re defense of the First Island Chain."

While it is true that the Soviet archives show that the speech was taken as evidence that the US was unlikely to expend significant resources defending the ROK, which in turn led to the Soviets greenlighting the invasion, it's also fairly misleading. The war was likely to happen, maybe in a different form, regardless of the speech and it also seems like the speech was simply used to justify the position of the hawks in reports, who could have swayed the situation either way. Still, the speech has become a part of all histories of the war because it's an easy to pinpoint misstep by an administration that was otherwise one of the best at grand strategy in US history (Containment doctrine being formed under Truman and winning the Cold War mostly peacefully).

I tend to mistrust all the information I read in the books and magazines, or said in the mainstream media recently due to lack of credulity on these sources, possibility of bias, and prejudice. I tend to rely on my own reason to judge either the information is true or false, or just discard them as non-sense.

But I cannot mistrust the perceptions of my own senses in my daily life, and knowledge about the world from my own inductive reasoning such as every life on earth will die eventually, or the Sun rises in the east.

All the sensory perception I have through my own senses must be taken as 100% truth until they are found, and proven as otherwise via self verification, logical thinking process or repeated observations.
• 442
From my perspective. I agree that the world looks flat to me when I am at home on Earth but it won't look flat if I was on the International Space Station.

Exactly. But more importantly the term "100% certainty" is consistent with being in error, as long as one is certain one is right, even if you're wrong.
• 692
I agree.
• 692
Please explain why you think: "All the sensory perception I have through my own senses must be taken as 100% truth until they are found, and proven as otherwise via self verification, logical thinking process or repeated observations." Thank you.
• 2.1k
Along with shared subjectivity, there is also exclusive subjectivity e.g. only I know the contents of my dreams and what thoughts and recollections occur to me.
Of course. Otherwise, if subjectivity were always "shared", the expression "shared subjectivity" would have no meaning, would it? :wink:
• 3k
Please explain why you think: "All the sensory perception I have through my own senses must be taken as 100% truth until they are found, and proven as otherwise via self verification, logical thinking process or repeated observations." Thank you.

You are welcome. The reason why I think that, is because I experienced in real life that my sensory perception is the most accurate source of truths. It has the possibility of getting wrong sometimes, but in most cases it has been accurate. If any truths I thought were found as falsity via verifications, observations and thought process, then they could always be corrected.

But all other sources of information are indirect, and it is often difficult to verify the truths. And in many cases, even what I read in the textbooks, history books, and watched on the mainstream media ... etc were found to be either as controversial, inaccurate or simply wrong. With repeated happenings of this, one learns to realise that the indirect information and so called objective knowledge is not reliable, and then I stopped buying them altogether being very cautious and doubtful in accepting the facts and information publicly available.

To cut the long story short, the old saying "Seeing is believing" summarises my points. :)
• 442

Well, if one can be 100% certain of essentially anything, right or wrong, accurate or inaccurate, as long as one is convinced you're right, then this thread dissolves into an essentially meaningless question, since the answer is: just about anything.
• 3k
One must be 100% certain of one's daily life sensory perception be it visual or sound. If not, then one will be in trouble leading a normal life. Imagine if you cannot trust your visual image of a bus on the road dashing into the pedestrian crossing, when you are just about to cross the road? If you feel that it is not a real bus, but just an image of a bus or a huge lump of chocolate sponge disguised, made up to look like a bus, and just keep on walking crossing the road, how long would you last in this world?
One must be 100% certain with one's own direct sensory perception even just to lead a normal life, let alone being scientist or telecom engineers what have you.

There will be times when one's direct sensory perception can be wrong due to the possibility of illusion e.g. I was seeing this black object on the ground beside the tall fern in the garden. From a distance, it looked like a black cat. But when I opened the blind fully, and had another look into the black object, it was a black bucket placed beside the fern, which looked like a cat. This type of perceptual illusions can happen, which have been re-observed, verified and corrected.

But indirect knowledge or information via television news, reports or interviews, rumours told by your neighbours or friends, or the contents of history books cannot be verified directly by oneself. Or you could, if you have time and finance and inclination to do it. You could fly to Ukraine, and observe and verify all the situations you hear on the media, by yourself. But would you?
• 692
Yes, indeed.
• 692
I agree with you but it is still possible that your perceived reality is a simulation or dream or hallucination or illusion. That's why I said I am 99.99% certain that my perceived reality is actually real.
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