"I i think therefore I am" seems like the only justifiable 100% certainty to me. The best you can get after that, I would think, it's 99.9 followed by some amount of 9s percent certainty - there's always some doubt for any other statement I think.

Thank you for your reply "flannel jesus." How would I calculate what percentage of certainty I assign to things such as the objective existence of my body, other humans, non-human organisms, the Earth and the rest of the universe?

Math and little more. At least in respect to generally or widely accepted notions and definitions of numeric constants and operations.

I suppose in a more philosophical area, the idea that questions exist and answers can be formulated, proven, and disproven. Albeit not to every individual's particular satisfaction or standard of burden of proof or level of scrutiny.

In short, "I think, therefore I am." .. or are you? Therein lies the proof there is at least some truth or falsehood and the ability to ascertain whether or not a statement or concept is closer or further away to each, respectively. If not at least by widely accepted standards, practices, and definitions.

Edit: That's amazing. I didn't even read @flannel jesus's post under after. lol

Great minds think alike I suppose :smile:

Thank you for your reply "Outlander." It is more accurate to say, "Like minds think alike." It is the fact that they think alike that makes their minds alike.

How would I calculate what percentage of certainty I assign to things such as the objective existence of my body, other humans, non-human organisms, the Earth and the rest of the universe? — Truth Seeker

Good question. I probably wouldn't even begin to go there. I am either convinced of something or not. Percentages add nothing. What is the difference between being certain and being 100% certain? Adding that percentage seems to be a scientistic way of saying, 'I have no doubts'. But so what? What is the difference between 100% and 95% certain? They are functionally the same in as much as we carry on and incorporate that 'certainty' (a bad word) into our presuppositions for life. I see no value in graduating certainty.

I have never subscribed to '100% certainly' style language for anything. My beliefs are based on 'reasonable confidence' via the best evidence I have available at the time. I take it as a given that we don't have access to any ultimate style truth and that truth is itself an abstraction which looks different in different contexts. We don't really need any more than this to go about our business.

Certainty is not a standard for knowledge. This is because you can doubt anything. Being able to doubt something lends no credence to whether a doubt is correct. Its what is irrefutable that matters. That you experience is irrefutable. To refute the idea that you experience, you must be able to experience. Therefore it is proof by contradiction.

Thank you "Tom Storm" and "Philosophism" for your replies. You have given me much to think about. So, is my perceived reality actually real or not? Do I have free will or not? Am I right to be a vegan or not? Am I right to be an agnostic or not? How would I know? This video: https://www.youtube.com/watch?v=uaxHTYtSavc is fascinating. Is Robert Sapolsky right?

Does the concept of 100% certainty involve an infinite regress?
A: I know X with 100% certainty.
B: But are you 100% certain that you know X with 100% certainty?
A: Yes, I am 100% certain that I know X with 100% certainty.
B: OK, but are you 100% certain that you are 100% certain that you know X with 100% certainty?
etc.

Thank you for your reply "Art48." I am 100% certain that I am conscious. No infinite regress is involved with this. Did you watch the Robert Sapolsky video excerpt? If so, what do you think?

The fact that everyone will die one day.

Thank you "Corvus" for your reply. I am 99.99% certain that I will die but I can't be 100% certain of it until I have died. If it was up to me, all living things would be forever happy and there would not be any suffering, inequality, injustice, and deaths. Sadly, it is not up to me. How would I know if others really exist? How would I know if others are really conscious or are actually philosophical zombies?

Thank you TS for your good topic. Unfortunately that is the only fact which I am certain now, which will take place in the real world as time passes by, as a truth. The rest, I am not so sure.

The fact that everyone will die one day. — Corvus

I thought the same, but I supposed that was obvious.

By the way, glad to see you around again, Corvus.

Thank you Javi for remembering me :D I have been busy with the other hobbies which are electronics, music and gardening.

For death of every life on the Earth, I was not so sure in the past. When I was a child, I believed people die, but they come back or resurrect next day - because I have seen a film, and the actor was killed and the film ended. I saw another film with the same actor but different role, and I recognised him, and thought to myself, wow people die, but they resurrect no problem.

As time goes by, and you get older, and you notice that was not true. Truth is that, everyone dies eventually, and they never come back forever.

Thank you for your reply "Art48." I am 100% certain that I am conscious. No infinite regress is involved with this. Did you watch the Robert Sapolsky video excerpt? If so, what do you think? — Truth Seeker

OK, I'd agree about 100% certainty of my own awareness.

I watched part of the video, but it’s part 5 of 6, so I decided to watch all of part 1 of 6 at https://www.youtube.com/watch?v=UX7bs4uvPyc

I think that no free will and entirely free will are two extremes, and the truth is somewhere in the middle.

Thank you "Tom Storm" and "Philosophism" for your replies. You have given me much to think about. So, is my perceived reality actually real or not? Do I have free will or not? Am I right to be a vegan or not? Am I right to be an agnostic or not? How would I know? — Truth Seeker

Answer: you don't know. Although this answer isn't satisfying to some, I think you just have to go with your intuitions. You can have reasonable confidence that you share a reality with others and that there are implications for how that reality is shared. Suffering seems real enough when experienced, so perhaps go with a worldview that works to prevent causing suffering (you can include being a vegan).

When it comes to gods I can't think of any good reasons to believe in them other than old books/traditions. My experience of the world does not include gods in it and, so the arguments (ontological, cosmological, from morality, experience, etc) are not especially relevant.

For me the experience of being human is living with uncertainty and knowing that much of what we believe or hold as true are constructions of mind and culture. I think this can only make life more interesting.

As time goes by, and you get older, and you notice that was not true. Truth is that, everyone dies eventually, and they never come back forever. — Corvus

Exactly. This can be one of the universal affirmative premises.

All one can know is what one perceives, and what one perceives is real at some level in one way or another. Real is anything that has effects in the world and it does not need to be exclusively objective or subjective. Ideas and even fantasies can be as effective in the world as anything else, and thus at a minimum have some measure of reality. The general theory of reflexivity by George Soros i believe illustrates this point well enough.

Certainty is a subjective term that is only applicable from the point of view of an observer with a question. However, the universe is 100% certain in what it will do, which is known as determinism ("the will of the universe"). From an observer perspective, probabilities or certainties fluctuate between 1% and 99%, and are determined by one's level of knowledge about the system in question. All variables that can impinge on the system must be accounted for, and the more complete one's information about the system, the higher the accuracy of one's predictions and thus one's level of certainty. Once an event of interest has passed, it is assigned 100% certainty or 0% if it did not happen.

If one were to calculate for instance what a proton will do in the next 5 seconds, one would need to include every particle state within 5 light seconds from the proton in their calculation. These other particles would all be components of the system that is the proton (everything within 5 light seconds = 1.5 million kilometers radius) that can have an effect on the proton within those 5 seconds. There is no need to calculate the state of the entire universe, but it's still not a thing humans can do yet.

Imperfect information yields imperfect probability projections and low certainty values.

I am 100% certain that I am conscious but it is not possible for me to know with 100% certainty that my body, other humans, non-human organisms, the Earth and the rest of the Universe actually exist. — Truth Seeker

Except tautologically, how are you "100% certain" of anything at all?

Certainty of factual accuracy of a subject is a comment on one's opinion concerning the subject, not an actual evaluation of the subject itself. In other words a simpleton can be 100% certain that the world is flat or the moon is made of cheese. In fact in a practical sense, the degree of a person's certainty is inversely proportional to their wisdom and life experience.

You are most welcome "Corvus." If souls exist, it is possible that souls reincarnate or resurrect after death of the body. I don't know if souls exist or not.

Thank you for watching the video and for sharing your thought about it. You can watch the full video here if you want to https://www.youtube.com/watch?v=nhvAAvwS-UA&t=135s

Thank you for your thoughtful reply. I find uncertainty difficult but I have no way to be certain of anything except for one fact: I am conscious. I am 99.99% certain that I will die but I can't be 100% certain of it until I have died. If it was up to me, all living things would be forever happy and there would not be any suffering, inequality, injustice, and deaths. Sadly, it is not up to me.

Thank you "punos" for your thoughtful reply. I am not a physicist, so please excuse my ignorance. Why would a proton be affected by other particles in a 5 light seconds radius? Surely, the zone of being affected would be mere millimetres or even less?

Thank you for your question. I am 100% certain that I am conscious because I am experiencing being conscious. It's a fact that is undeniable to me. Although, I can't prove to others (if they really exist) that I am not a Philosophical Zombie https://en.wikipedia.org/wiki/Philosophical_zombie - if others really exist they can't prove to me that they are not philosophical zombies either.

Here are some things I have done, currently do or will do even though I don't want to do them:

1. Breathe
2. Eat
3. Drink
4. Sleep
5. Dream
7. Pee
8. Poo
9. Fart
10. Burp
11. Sneeze
12. Cough
13. Age
14. Get ill
15. Get injured
16. Sweat
17. Cry
18. Suffer
19. Snore
20. Think
21. Feel
22. Choose
23. Be conceived
24. Be born
25. Remember some events that I don't want to remember
26. Forget information that I want to remember
27. Die

What I really want to do is go back in time and prevent all suffering, inequality, injustice, and deaths and make all living things forever happy but I can't do it. I am doing things I don't want to do. I can't do what I want to do. So, how can I have free will?

I do not accept 'I think therefore I am'; I do not see how you can assume that thinking necessarily implies a thinker. We have a prejudice that verbs require a subject, which can sometimes require some linguistic acrobatics. What is the 'it' in 'it is raining'? By assuming that thinking implies a being that is doing the thinking, you are begging the question. The best you can do is to say something like 'thinking, therefore thinking'.

Do we know with 100% certainty that we're in extreme pain? High? Depressed?

I object to quantifying uncertainty as a percentage or fraction. In order to calculate a probability, you need a model and a set of assumptions. You are saying that 'Given my model is right and my assumptions are correct, the probability is x%. 'I assume that the coin is fair, and that an infinite number of coin flips under these specific circumstances would yield an even number of heads and tails.......' Otherwise the percentage that you quote is only a statement of your emotional commitment. The existence of anything beyond the perception of thinking is something for which evidence is not available, but it can still be accepted as a 'working hypothesis'.

We can know with 100% that pain exists. Could we tell we are high or depressed if we cannot be sure of our comparisons with not-high or not-depressed?