CharlieBlack wrote:

What does certainty mean?

Beyond the possibility of reasonable doubt.

Last edited by nojoum (4/29/2017 4:13 am)

DanielCC wrote:

nojoum wrote:

If not, then what is the point of doing philosophy? To me, it seems a big failure for philosophy not being able to give answers with full assurance.

In that sense I doubt any discipline can ' give answers with full assurance' - simple arithmetic but that would be all. Likewise the conclusion you propose, that it represents a failure of philosophy, would not be reachable in any way which would satisfy those standards.

The aim of other disciplines such as applied physics, applied chemistry, chemical engineering, bio engineering, (basically applied sciences as a whole) is controlling and predicting the natural world. It is also obvious these disciplines are successful at their endeavors.

However, the point of philosophy is to have knowledge of the world. It is also reasonable to assume that knowledge should come with certainty. Therefore, we can say since philosophy has not produced certainty, it has failed in reaching its goal.

nojoum wrote:

I would like to ask is there anything that we can claim to know with 100% certainty?

It's worth distinguishing purely subjective certainty from formal certainty. Purely subjective certainty is assent that is firm, but shouldn't be, because it doesn't rest on anything objective; formal certainty is firm assent that corresponds to objective reality, and rests on objective grounds. I assume your question is about formal certainty, and shall call the negative answer's thesis—that there can be no formal certainty—universal skepticism.

a. Now, either knowledge entails formal certainty, or it doesn't. If it does, then by universal skepticism there can be no formal certainty that universal skepticism is correct, and it's impossible to know that universal skepticism is correct.*

If knowledge doesn't entail formal certainty, then it's possible to know things without being formally certain and it's not as big a deal that it's impossible to be formally certain of anything.

b. Universal skepticism is also less certain than that it's formally certain that I exist, that the apple I had in my hand a second ago is one and the same as the one I took a bite out of just now, that I have a head on my shoulders, and so on; it, however, entails that the latter, more certain truths are false; hence, we can't consistently hold both universal skepticism and those latter truths; hence, we ought to reject universal skepticism.

Hence, we have conclusive reason to reject universal skepticism, and admit that—here comes your answer—there is something we can know with formal certainty.

(Or, if you prefer: universal skepticism conflicts with perfectly evident truths; hence, universal skepticism is absurd; hence, universal skepticism is false. If universal skepticism is false, there is something we can know with formal certainty.

So to answer, there is something we can know with formal certainty.)


*You can play down the importance of knowing that universal skepticism is correct, but then in the same way it's not as important that we know various other truths universal skepticism denies our knowledge of.

Just because you found something subjectively difficult does not actually mean that there was a problem with an argument.

I have seen students of Calculus insist that the whole thing doesn't make any sense and doesn't prove anything just because they found it difficult.  One of my own students insisted to me that modus tollens was invalid because it didn't make sense to her.

I think the popular conception of how much consensus there is in science and how little consensus there is in philosophy is deeply misleading.  As a matter of fact there are widespread divisions over fundamental questions in science.  GUT has been famously elusive.  On the other hand, there is a lot more consensus in philosophy than might first appear to be the case simply because philosophy typically proceeds by laying out all the views regardless of the real percentages of people who believe them.  For example, I don't know anyone professionally who disagrees with the law of noncontradiction.  David Lewis is famous for being one of a vanishingly small percentage of philosophers willing to embrace modal realism.  I could go on and on.

If we are going with subjective level of certainty as a kind of confidence level, I am more certain that God exists than that electrons really are the way they are described in my physics textbook.