Excellent point. It is possible that the self is an illusion and thoughts and emotions and words and actions simply happen as a result of brain activities.

You are right.

Yes, at least, I do. I can't speak for you or others.

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? — Richard Goldstein

You would probably need a point of comparison to figure out if you are high or not, but depressed? Do you have to have experienced non-depression to know you're depressed?

I would say that "certainty", in the sense of absolute--beyond a doubt--confidence of the truth of a proposition, is only a derivative of uncertain reasoning, as it is defined by an inductive commitment to the principles of logic. Thusly, the truth of a proposition is said to be (absolutely) certain iff it is logically impossible for it to be false.

Therefore, only what is deduced from the inductively ascertained grounds of logic is said to be certain. Such as, for example, 'a = a'.

For me, consequently, absolute certainty only pertains to the form of an argument and never its content; and only certain principles of that form which I inductively commit myself to.

In the sense of some sort of absolute certainty, some absolute ground, from which one can begin their reasoning, I find it to be non-existent. One is only afforded degrees of confidence at the roots of their derivations.

If it is possible to be 100% certain of anything then it must be the case that we can be 100% of something.

If it is possible to be 100% certain of something then we must know what "100% certain" means.

I do not know what "100% certain" means.

Therefore it is not possible to be 100% certain of something, and therefore it is not possible to be 100% certain of anything.

I am 100% certain that I am conscious — Truth Seeker

I would say that to doubt oneself is self-contradictory to say the least. :naughty:

Thank you for giving me more food for thought.

By "100% certain" I mean completely certain. I am completely certain that I am conscious. I am almost completely certain that I will die.

I agree with you.

Do you have to have experienced non-depression to know you're depressed? — RogueAI

A provocative question.

100 % just means 100 out of 100 cases?

"“Per cent” means “out of every 100”. Percentage figures are derived by dividing one quantity by another with the latter rebased to 100. Percentages are symbolised by %. Besides being especially useful when making comparisons, they come in handy for studying a difference compared with a benchmark or initial value." - Google

How would I know if others really exist? How would I know if others are really conscious or are actually philosophical zombies?

Eventual death of all life is definitely more certain than doubts on other beings existence or consciousness from general induction.

Please bear in mind everyone ever born on the Earth have all died, and are still dying even at this moment.

And not knowing something doesn't have relevance with more certainty or less certainty. Your not knowing something just means you don't know it.

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. — Truth Seeker

When the word "Souls" is uttered, it indicates the speaker is already speaking from religious or artistic literature point of view, which is based on faith / belief / imagination, not fact or knowledge.

I have never witnessed detached souls reincarnated from dead bodies in real life. I have read about souls in fictions and poems and religious texts.

I agree with you.

I have never witnessed souls either. I am an agnostic regarding the existence of Gods, souls, reincarnation, resurrection, karma, etc.

I think it's easier to be 100% certain of what is not, rather than what is.
From that position, I am 100% sure of many 'is not's.'
I am 100% sure that I am not omnipotent, omniscient, omnipresent, omnibenevolent, etc, etc.
I am 100% sure I don't own a castle.
I am 100% sure I am not Donald Trump.
I am 100% sure many people (including some on TPF) are illogical and irrational.
! am 100% sure Harry Potter and Darth Vader were not real people. I have no choice to drop that 100% surety to something less when it comes to God, Jesus, Allah, Zeus etc because I cannot confirm 100%, who the original authors of such stories are.

I have never witnessed souls either. I am an agnostic regarding the existence of Gods, souls, reincarnation, resurrection, karma, etc. — Truth Seeker

Yeah, when it comes to having faith in / believeing in God, souls, reincarnation, resurrection, etc, there is no room for certainty. Because there is no certainty, one has to have faith and belief in them.

I agree with you.

I agree with you.

In that case I'd say I'm completely certain of many things. But importantly, I've been completely certain of beliefs which have turned up false. So I'd draw a distinction between certainty and knowing that my knowledge is true and infallible.

In that case I'd say I'm completely certain of many things. But importantly, I've been completely certain of beliefs which have turned up false. So I'd draw a distinction between certainty and knowing that my knowledge is true and infallible. — Moliere

There is again difference between bogus certainty and genuine certainty. Just because one felt something was certain, does NOT mean it was truly certain.

I'm not so sure. For instance what if the belief was truly certain and it only turned up false because the world changed?

I am certain that my fridge has pickles in it. I open the fridge to find there are no pickles -- someone must have eaten them in between, and so what I was truly certain of turned out that I could no longer be certain of. But I was certainly justified, even epistemically, in my belief since I put the pickles in the fridge.

A lot of the time I think our desire for certainty falls to this -- we're certain of things, but things are subject to change. And so the desire for certainty is to somehow overcome change so that no matter what happens I'll know what I believe is true and infallible. But this is an entirely different kind of certainty to the more mundane one I presented: it's changing what's required of certainty not just so that we're certain, but so that we'll always be certain.

Of course, things change, and even 1+1 =2 is not certain truth.
1 man and 1 woman married and became 2 people in the family. A few years later they had offsprings, and the family became 3 and then 4. So was 1+1=2 true? No, 1+1 became 4.

So all certainty is subject to change by time, or situation or process be it natural or artificial.
Certainty is not something that is absolute and fixed concept. It is relative and changeable.
You always get percentage of certainty. Some certainties are more certain than other certainties.
Therefore I suggested "All life on the earth will die eventually." was one of the 100% certainty. Because it is a conclusion derived by billions and billions of examples in millions of years of historic records, the biological facts of lives + the on-going processes happening right now. There maybe other 100% certainty cases, I am sure.

But Gods, souls and reincarnation? Where is your data? physical evidence? witnesses? Nothing? You must recourse to faith and belief.

I agree with your example of the pickles.

1 + 1 = 2. 1 + 1 does not equal 4. Two people can become parents of two children and that would cause the number of people in that family to increase to 4. That does not change the math 1 + 1 = 2. The math in that case is 1 + 1 + 1 + 1 = 4.

I agree that religious beliefs are faith-based rather than evidence-based. Religions contradict themselves and each other. Please see: https://skepticsannotatedbible.com and https://www.evilbible.com

However, if our perceived reality is not actually real, then science can't be relied upon to give us facts. Science assumes that what we observe is real and not simulated or dreamt or hallucinated, etc. It is not possible for me to know with complete certainty that my body, other humans, non-human organisms, the Earth and the rest of the Universe actually exist.

According to Hinduism, our perceived world is an illusion called Maya. It is created by the Hindu Gods to test living things. It is impossible to prove or disprove this claim.

I was talking about the people in the family. It started with 1+1=2 people, but later through time and the process, the member in the family became 4. The added 2 originated from the already existing 2, not added or come from outside somewhere. In this case, could it be said 1+1+1+1=4? It would be rather 1+1 (later +1+1 never existed before the original 1+1=2) =4

For other example, you get 2x separate bricks, and glue them together with cement mortar, it becomes 1. So 1+1=1 not 2.

Thanks for the links. Interesting read. :up:

I suppose you can't doubt that something exists.
Not exactly informative, though, hardly a fantastic epistemic discovery/development or grand philosophical innovation.

Can you doubt that this is English?
Not really, which is a bit more informative.
I suppose, however unlikely, that an alien could happen to find it a description of a comet they're in the vicinity of, not knowing English in the first place.

This: Thoughts therefore exist. (← A more accurate version of cogito ergo sum.)

You are most welcome.

I agree that I am certain that we are communicating in English as opposed to any other language. Thoughts, emotions, perceptions, recollections, etc. exist even though we don't know whether souls exist or not and whether brains really exist or not.