What can we know for certain?

To me Philosophy is the pursuit of truth through logical deduction based on unpresupposed knowledge.

But, if this is the case, where do we begin: what can we know for certain? Anything?

Our perception of our world might just be a figment of our imagination of course (all in the mind). But can we be certain our mind exists? Can I (or in turn you) be certain I (or you) exist?

Descartes seemed certain that he existed when he said, “I think therefore I am.”

Can you be as certain as Descartes about your existence. If so, what is you reasoning for this?

If you are thinking then something must have made those thoughts, ie you - whatever/wherever/whenever you may be.

I can only think im thinking, but i know i am.

Hi Moonface,

Welcome to the boards. The question of certain knowledge has been discussed a few times before. Perhaps to enrich this thread you might like to have a look at:

Descarte’s Cogito
ilovephilosophy.com/phpbb/vi … p?t=139326

I Think Therefore I Am
ilovephilosophy.com/phpbb/vi … p?t=139343

Descartes and Knowledge of self
ilovephilosophy.com/phpbb/vi … p?t=139195

What can be called into doubt
ilovephilosophy.com/phpbb/vi … p?t=139202

Knowledge and the possibility of error
ilovephilosophy.com/phpbb/vi … p?t=138906

Russell, Descartes and the Sceptic (An essay)
ilovephilosophy.com/phpbb/vi … p?t=139319

Hope this helps

• ben

Define certainty!

Is it certain that 2+2=4?

If it is certain that 2+2=4, then it is also certain that God exists, since both statements rely on undemonstrable and assumed first principles, in the case of arithmetic we assume the definition of an unit and in the case of metaphysics and physics we assume Causality and a First Cause.

Kant distinguished between “I am certain” (which he called “subjective certainty”) and “It is certain” (which he called "objective certainty). To say that I am certain that… is to say that I feel very sure that…is true. But we all know that feeling very sure that something is true is no guarantee that it is true. Some people feel very sure (are certain) that God exists; and some people feel very sure (are certain) that God does not exist. And, since they both cannot be right, and one side must be wrong, feeling very sure, does not guarantee that what you feel very sure about is true.

“It is certain that…” (Objective certainty) means that it is impossible that … should be false. Not just that it is not false, but that it is impossible that that it should be false.

That might only mean that only truths like 2+2=4 are certain, simply because they are what are called “necessary” truths in the sense that their negations are impossible.

Although some have maintained (like you) that God exists is a necessary truth, there is a very powerful objection to that view: it is that no existential statement can be a necessary truth because that would imply that existence was a property, and existence is not a property of anything. This is a very complex issue, but just let me say that if existence were a property of anything, then it would be true that the difference between unicorns and horses would be that horses have property that unicorn do not have. But that seems wrong, since unicorns have no properties for the reason that they do not exist, and only what exists can have properties.

How do you know that unicorns do not exist? Can you prove it? How many planets have you visited besides Earth?

Unicorns certainly do have properties as do every other imagined species.

Since the First Cause of all that was, that is, or that ever will be, is perfect and infinitely creative, it would be limiting God’s infinitely creative abilities were we not to admit that unicorns and chimeras actually exist somewhere in the infinite universe. All of the beasts of our imagination exists somewhere in the infinitely creative universe of spacetime. Chimeras are real. Fear them.

The number 2 and the number 4 is not a representation. They are abstraction layers of base truth 1. If there is one, and there is zero, than anthing that is equidistant from 1 in the opposite direction is designated 2. 2 exists, even if the “word” 2 is a symbolic representation. The concept is universal. Same deal with 4, a number that is equidistant from 2 is to zero in the positive direction.
2 + 2 = 4 is certain. We know it. (what are you going to say, 2 + 2 = 5 for sufficiently large values of 2?? laughs).

Now, it’s certain that 2 + 2 = 4…how does that mean god exists? I’m sorry, but isn’t the definition of a god “that which none greater can be concieved?” First Cause is insufficient as A) causality is not definitie, and therefore is a shaky premise, B) why would the Uncaused Cause have be sentient, as sentience is better than being inanimate…because one cannot do good without knowing one’s self. A rock doesn’t do good or evil.

If you ask me, the only thing I know is that I exist.

I cannot doubt that I doubt. shrugs

By the way, Descarte did not come up with this idea. Hell, he didn’t even come up with the Ontological proof of God. That was St. Anselm. Descarte didn’t come up with the proof of one’s existence, either. That was good 'ol St. Thomas Aquinas. I hate Descarte. He took two interesting concepts, overcomplicated them, and in the end, accomplished nothing but strengthen the false idea that religion is a rational institution that serves a purpose other than itself. He’s a true example of why people who rephrase what others say are not philosophers, but are historians. Historians never get shit right, and it’s always the victor who writes the history books.

(and yes, I see the irony in me saying that)

Tu, qui vis te nosse, scis esse te? Scio. Unde scis? Nescio. Cogitare te scis? Scio. (roughly -“You, who does not know with certainty [strength], do you know this to be you? You know. From where do you know? You don’t know. To think, do you know you? You know.”) - St. Thomas Aquinas

Prove that an unit exists and I will prove to you that there is a First Cause.

Please do…you certainly haven’t managed it in your eighty or so posts on the subject before. Suppose a unit exists. That unit must have a cause because we know (or at least assume) that everything has a cause. But you believe in a First Cause–one that is UNcaused. That means that, on your view, not everything has a cause (based on Aristotelian logic). If everything truly has a cause that means there must be an infinite number of causes. Full stop. If there is an uncaused cause then the entire idea of causality just crashes and burns. I’d like you to provide an argument at least that long as to why my conclusion is false. Telling me to read Aristotle doesn’t count because I’ve read Aristotle and think he’s wrong.

And when you’re finished explaining why there is a First Cause, kindly tell us why that First Cause must be God. (and for God’s sake and your own self-respect, don’t appeal to Bertrand Russell; that’s what the Sophists did: they contradicted themselves in order to win arguments)

This absolutely does not follow. The two rest on entirely different first principles. The mathematical one is analytic (necessary); it must be true in order for anything to be true. The God concept is a first priniciple of faith alone.

…is what that should have read. An imagined property is much different from an actual property in that an imagined property is nothing but a THOUGHT. An actual property is an observed aspect of the world.

Surely God can choose NOT to create something if he doesn’t want to.

But this whole idea of God creating every possible thing rests on the assumption that God exists…which you have yet to demonstrate.

Mkay. read this page.

ilovephilosophy.com/phpbb/vi … 3&start=20

No, we cannot be certain without using faith, and we all knwo the folly in that. But does the fact that we cannot know change anything, does us being, or existing, make us any less important to ourselves? Does our environment actually existing, make it anymoreor less usefull to us?

If we exist, then clearly it does not matter if what makes us happy, and content actually exists, it doens’t change the fact that it makes us happy and content. The object itself is quite irrelevant to our happiness, and comfort, it’s all on how we interpret, perceive, and value the object. If it doesn’t actually exist, it doesn’t change the fact that we precieve it to exist. Or think we preceive it to exist.

And if we don’t really exist, then that doesn’t change the fact that we precieve, experience, and value ourselves.

Would it be more fullfilling if we knew for a fact that we, and everything around us truly exists in an “absolute” state? Probably!

Can we keep living not knowing, can we enjoy everything just as much with out knowing, can love,hate,value,enjoy without know? Absolutely

Why? Suppose God exists!

If you’re going to assume Causality you might as well assume God.

Correct.

Only the First Cause is Uncaused.

An infinite number of accidental causes but only one First Cause.

Why? The First Cause is Uncaused by definition.

I’d like you to prove there was no Big Bang, prove the Universe is Uncaused and prove God doesn’t exist.

God is the First Cause by definition and by Western convention.

I won’t appeal to the Sophist Russell. I will appeal to perhaps the greatest genius – Aristotle.

“There are some people who expect even this to be demonstrated, but on account of lack of education, for it is a lack of education not to know of what one ought to seek a demonstration and of what one ought not *. For it is impossible that there be a demonstration of absolutely everything (since one would go on to infinity, so that not even so would there be a demonstration), and if there are certain things of which one ought not to seek a demonstration, these people are not able to say what they think would be of that kind more than would such a principle. But even about this there are ways to demonstrate that it is impossible by means of refutation, if only the one disputing it says something; if he says nothing, it is absurd to seek an argument to meet someone who has no argument, insofar as he has none, for such a person, insofar as he is such, is from that point on like a plant.” – Aristotle (Metaphysics, 1006a)

• “This sentence demands careful reflection.” – Martin Heidegger, The End of Philosophy and the Task of Thinking

The metaphysical is analytic (necessary); it must be true in order for anything to be true. The unit concept is a first principle of faith alone.

You mean imagined properties like Space, Time, Number and Causality?

The concept of an unit is an assumption and a defintion just like the concept of God is a definition and an assumption.

That’s it. I’m not posting again until this maniac is banned.

I guess people define certainty in different ways.

Some people are certain of something because they perceive it with their senses, others because their teacher said so, others because they have a gut feeling about it, some because it ‘seems’ logical or reasonable in a very liberal sense.

Because ‘certainty’ is so vague a term, relative to ones beliefs, is just why philosophy needs a sound methodological approach. I still think my definition of philosophy as ‘the pursuit of truth through logical deduction from unpresupposed knowledge’ is a sound road toward certainty.

If their are any assumptions involved in the above method they are that the strictest of human logic leads to truth. However, if we were to rule out such as certain, with what methodology are we attempting to make that claim? Answer: human logic of course. To argue that ‘human logic is uncertain’ is a poor argument (as we are disqualifying the very method that we are using to make the claim).

It appears then that we are ‘stuck’ within the restraints of our human logic. And the fact is we can never see outside that. It is our ‘truth’. It is as real to us as anything can and ever could be. To see outside it would mean we were no longer human, no longer ourselves.

So our logical capacity is our truth. If there is something else beyond that it is pointless us trying to conceive it, as it is beyond our capability. It would be meaningless to us, and so might as well not exist to us anyway. it could never be ‘real’ or ‘true’ to us. It is not our world. It could never help us in our present life existence.

All that is certain for us is what we can be sure of from our perspective from the strictest of reasoning. Reason and logic are the essence of our being. In our reasoning alone is where certainty can be found. To try and argue against this is to attempt to argue outside of our own capacity for reasoning which is clearly foolishness and illogical in itself.

What is “unpresupposed knowledge”? Can you give us an example of “unpresupposed knowledge”?

Why are you assuming anything? What is “the strictest human logic”? Can you give an example of a logical truth that can be proved without assumptions?

To argue that a First Cause is uncertain is a poor argument (as we are disqualifying the very method [Causality] that we are using to make the claim).

Do you deny your own existence?

No?

Then are you not “one”?

Boom, the unit exists.

Your question, “do you deny your own existence?,” is based upon assumptions. “You” are assuming that there is a “You” and a “Soul,” you are assuming that there actually is being, you are assuming that you are not a brain in a vat. You are assuming that an unit exists.

By talking with you, I’m making an ASS out of U and ME.

I was asking a question, the answers of which prove a base unit. You can answer the questions without making any assumptions, but I cannot phrase the question without any assumptions.

Man, you’re dense.

Ok, let me reprase.

Do I deny my own existence?

No.

I am one.

One exists.