The Instigator
Pro (for)
5 Points
The Contender
Con (against)
0 Points

Logic without experience/experimentation can not achieve certainty

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Voting Style: Open Point System: 7 Point
Started: 4/2/2012 Category: Philosophy
Updated: 4 years ago Status: Post Voting Period
Viewed: 1,258 times Debate No: 22514
Debate Rounds (3)
Comments (4)
Votes (2)




Resolved: Logic without experience/experimentation can not achieve certainty outside mathematics about things which are not mathematically expressed.

Clarification: The debate does not concentrate on mathematics. Mathematical logic is excluded as the only place where we can actually reach a kind of certainty by the application of pure logic. The argument will instead concentrate on the futility of certain 'logical' arguments. Also I would be grateful if we could avoid defying common sense just to win the argument. In this way we can have a discussion from which we can learn something.

The burden of proof is with Pro (me).


1. Acceptance/Clarifications/1st argument
2-3 Argumentation

Only join this debate if you are serious about the topic.
No Semantics please!

In this debate I put forward the proposition that philosophical discourse using ideas for which we have no certainty can not be fruitful. Logic is of course effective as a method of reasoning with which we can reach valid conclusions. The problem we are facing is that we use valid logical structures but the concepts behind our premises sometime range from vague to completely unknown. This is more apparent in discussions about big issues such as the meaning of life, god, purpose of the universe etc. It can also be vague when dealing with human things like debates on morality or politics but in these subjects it is definitely more routed in common sense.

To clarify what I mean observe the following examples:

Therefore, A->C.

Sissi is a cat
All cats have a tail
therefore Sissi has a tail

Until here everything is good. We are all certain that all cats have a tail (from our experience), therefore we are certain of the result of the argument. But what if the argument was like that:

Sissi is a cat
All cats possess 38 chromosomes
therefore Sissi possesses 38 chromosomes

Hmm.. Sounds plausible since it appears scientific, but we need to check if it is true. In order to know that it is true we would have to actually be a biologist or at least understand what a chromosome is and the mechanism by which we can find out that a cat has 38 chromosomes. Ideally we should also apply the procedure, make the count and finally know that the statement is true. Of course most people will go up to checking Wikipedia (as I just did myself) and maybe a couple more sources if they want to 'make sure'.

So quite different types of 'certainty' there, and I am sure everyone will agree that his/her confidence on the 2nd argument is a lot higher than the 3d one (except if you are indeed a biologist). In any case we can definitely say that it is at least plausible to attain that knowledge and not completely futile to argue the point without doing all the research as our experience has shown that science is trustworthy.

Now the real problem comes when the discussion goes into subjects that are dealing with unseen and unmeasurable concepts. Take this as an example:

Sissi is a biological organism
All biological organisms have a soul
Therefore Sissi has a soul

Probably at this point you are all thinking here is another atheist preparing the ground for his attack :) Well that is not the case but it is not todays topic either. I am sure it is immediately apparent where I am getting at. What is a soul? How do we know that cats have one? Now, if you can define soul and prove, or at least indicate its existence through the scientific method or direct experience, then we can continue with our discussion. If not, a soul (whatever that is) may or may not exist and one thing is certain: we can not move any more closer to certainty in this logical argument.


I have indicated why certainty can come from experience or experimentation. There is the potential that it can be reached using logic if the individual elements are already certain. If that is not the case logical argumentation is futile and should stop (except if it is used as a form of entertainment).

Can Con provide a logical example where this is not the case?


The BOP is on PRO. Therefore I simply must thrust my arguments in and my opponent must still prove his point. I could simply refute his claims and the debate would be lost him but that is ok. So my opponent makes the argument put very simply that outside mathmatics we need experience.

The case for the reasonableness of solipsist belief[1]

For the record the reason I bring up solipsism is because if a solipisist postition is correct then no empirical evidence can be used in logic because only reason can be the guide. It is the only reliable evidence.

My opponent and anyone denying the reasonableness of the solipsist position must be against the concept of epistemic certainty, for that is all that solipsism is. Take an apple or a chair or a light bulb and ask "Could that possibly be an illusion?". The answer is of course yes. It happens all the time. Our senses deceive us. Whether one is a schizophrenic hallucinating wildly or a nervous man seeing what his mind projects in a shadowy alley, it cannot possibly be denied that one's senses can sometimes be and sometimes are wrong. All the solipsist does is admit this and adjust their epistemic (and metaphysical) outlook accordingly. One can never know with certainty that anything outside of one's self certainly exists and thus one would not be justified in believing so. Written in syllogistic form, the reasoning goes as follows:

P1: One is only justified in believing that which can be known with complete certainty.

P2: One's self (mind) is the only thing which can be known to exist with complete certainty.

C: One is not justified in believing in anything except for one's mind.

Defense of Premise 1

I suppose the initial bar with which the solipsist sets that which can be known is what is most controversial about the position. After all, most people think that when their eyes see something, it's justified to believe so. However, one must realize that the certainty one derives from what one's eyes register (a posteriori propositions) is wholly inferior to the certainty one derives from logical necessity or reasoning (a priori propositions) as far as certainty is concerned. It is possible that one is not registering correctly what one is looking at and thus one can possibly have unjustified belief. This does not hold for a priori reasoning. If one's logical reasoning is correct, it is not possible to hold unjustified belief. The rationalistic method of acquiring knowledge is clearly more justified and more apt to yield correct results and certainty than the empiricist method.

Defense of Premise 2

Upon initial reflection, nothing can be found to necessarily exist with complete certainty other than the mind itself. Even the concept of one arguing that their mind does not exist sounds like rubbish on it's face. In order to refute this premise, my opponent would need to show why something other than the mind can be shown to exist with complete certainty, certainty wherein the concept of denying it's existence is self-contradictory.

Defense of the Conclusion, Validity

The argument itself is clearly valid. Premise 1 asserted a theory of what qualifies as justified belief, Premise 2 argued what stood up to those qualifications, and so the conclusion is necessitated if the premises both hold to be true.
Defense of Rationalistic Perspective.[2]

“I think therefore I am” stated the French philosopher René Descartes. Descartes had doubts that he existed. He concluded that if one doubted their existence then that proved thought had occurred, and thought confirmed existence of self, hence the statement “I think therefore I am.” The only thing that Descartes could be sure of using his method was his existence. Descartes’ mind and his rational thought were used to arrive at his conclusion since empirical knowledge cannot validate existence. Empirical knowledge cannot be used to conclude existence because sensory experience alone is not enough to raise doubt of one’s existence. Doubt of existence implies logic and reason. Such doubt requires a venue for occurrence, that venue of occurrence is the existent individual using their abilities to reason.

Seeing is not believing. Sensory experience alone can not be trusted because it can and will deceive you. Take for example a dream. Within a dream we are almost certain we are experiencing reality, but once awakened we know this is not the case. We think that a dream is reality because our senses are still intact as we experience the dream world created by our thought. We experience the dream world that is created by our mind through our senses but a dream is not real and we cannot gain knowledge or truth from it. If our senses are capable of deceit in a dream then it is reasonable to expect them to do so in reality as well. For example, say I look into the distance and see two kids playing. My sense of sight is providing me with this information. I soon realize that these children are not playing, but in reality they are fighting. My senses deceived me and lead me to believe that the kids were playing; however it was through my logic and reasoning of the sensory information provided that I was able to conclude that I was watching a fight. Truth cannot be provided without proper reasoning and logic which provides the senses with judgment.
Note on A Priori Knowledge.[3]

We seem to know some things a priori, or at least to be justified in believing them. Standard examples of propositions known a priori include: a bachelor is an unmarried male; 2 + 3 = 5; if you know something, then what you believe is true; if A is greater than B, and B is greater than C, then A is greater than C; no object can be red and green all over at the same time; the shortest distance between two points is a straight line; no object can be wholly in two different places at the same time; it is wrong to torture infants to death just for the fun of it; and it is unjust to punish an innocent person.

For the sake of argument, assume that we know that all of the following claims are true: some bachelors are unhappy; there are five apples in the bag; I have hands; my middle finger is longer than my ring finger, and it is longer than my little finger; the tomato I'm holding is red all over; the shortest route by car from Detroit to Chicago is along I-94; I was in California in mid-March, not Detroit; torture produces unreliable testimony; and people who are punished unjustly become resentful. The basis of the knowledge of these claims is different from the basis for knowing that bachelors are unmarried males, 2 + 3 = 5, etc. The basis for knowing that bachelors are unmarried, etc., is also different from the basis for knowing that I now have a pain in my left knee, that I ate cereal for breakfast this morning, and that there was a massacre at Virginia Tech on April 16, 2007. The basis of a priori knowledge is not perception, introspection, memory, or testimony (cf. Casullo 2003, 29-30; BonJour, 1998, 7). If there were such things as telepathy and clairvoyance, they also would not be the basis of a priori knowledge (Casullo 2003, 149; BonJour 1998, 7-8). A priori knowledge and justification seem to be based on reason alone, or are based solely on understanding the proposition being considered.

Knowing all this there can be no other vote but a negative today. Vote Con.

Debate Round No. 1


First of all my thanks to Con for accepting and engaging with this debate :)

Con said:

"The BOP is on PRO. Therefore I simply must thrust my arguments in and my opponent must still prove his point. I could simply refute his claims and the debate would be lost him but that is ok. So my opponent makes the argument put very simply that outside mathematics we need experience."

I am not 100% sure what this means since it is not phrased very clearly. I have presented my argument very clearly and Con's involvement demonstrates that he has understood it and is now trying to refute it. I would also like to point out that Con's refutations are self contradictory as he first argues in favor of solipsism, and then in favor of a priori knowledge! The one view is talking about not being certain about anything and the other one about being certain without knowing why. I will assume that Con is just playing devil's advocate ("thrusting his arguments").

Let us examine the individual arguments.

Con's argument [1]

Con said:

“For the record the reason I bring up solipsism is because if a solipsist position is correct then no empirical evidence can be used in logic because only reason can be the guide. It is the only reliable evidence.”

To come back to my original point can Con give me an example of reason operating without experience/experimentation outside pure mathematics?

The solipsist view is an extreme view. The key phrase is "if a solipsist position is correct". Such a view denies everything that we are. The first and foremost argument against it is that our whole operation is based on our ability to interact with the world. Even Con I am sure will admit that his operation in the world is not based on pure reason and that the results, if not perfect, are quite reliable. I have a sense of where my kitchen is and where the fridge is (yes I am thinking of food :)). Well yes I assume, but the evidence towards my assumption are overwhelming. I have done that again and again and I can be confident that the outcome will be the same. Tell you what. I will check ...

... I was right! The kitchen was there and the fridge was there as well. Believe me I really did it! I have been doing this experiment for the last year that I've been living here and the evidence is pretty conclusive.

NOTE: Could it be a dream? No, cause I checked (more about that later).


Yes our sense are imperfect and not totally reliable. Yes our 'certainty' could be described as being statistically reached. But from that does not follow that everything we perceive is unreliable (see fridge example). Sorry to repeat my self but can Con give an example of something outside mathematics that can "be known with complete certainty" in general, and without being based on experience or experimentation(!!). I think that what Con is talking about is just inconceivable. A play of words.


Again the key here is how we define certainty. In a philosophical discussion it is really confusing but using common sense it quite evident. The easiest way to think about it is that we have statistical evidence regarding our experience of the world. We could say that there are different degrees of confidence but even if we are talking about absolute certainty that does not have anything to do with my point.

I stated that "Logic can not reach certainty without experience/experimentation" and all Con is trying to prove is that logic can not reach anything at all since nothing is certain.

The whole solipsism argument contradicts everything we are and everything we have achieved. It has been already philosophically refuted by Moore[1] and Wittgenstein[2]. I hope you will appreciate that I can not give an overview of their arguments because these complex writings have to be considered as a whole and cause my space is limited.

Con's argument [2]

There is only an overview, the dream argument and the kids argument. There are many ways that we can realize that we are dreaming while we are are dreaming. This is called lucid dreaming (LaBerge[3]). Dreaming as a different state of consciousness has its own characteristics. If Con is confusing dreams for reality (I assume and hope that he is not doing it the other way around) then he should refine his perception. Many things are different, ranging from objects and people constantly transforming to expectations manifesting as reality and there are also reality check techniques. Concerning the kids argument can Con demonstrate how exactly the mind concluded there is a fight using logic that is not based on experience?

Con's argument [3]

This is an overview and not an argument. I will just refute one of Con’s a priori' knowledge examples to keep things going. "A bachelor is an unmarried male" can only be understood based on experiential facts. This should be self evident but I will expand. The word bachelor is a complex concept that presupposes that we know what is “unmarried” and what is “male”. How did Con learned the concept of male. Did he used reason? No. He learned the concept probably by his parents pointing towards him and his father, after he asked the question himself or something along this lines. The main point is did he learned the concept without experience? Again, this is inconceivable and I challenge Con to tell me where and how exactly did he reason out the word male and unmarried in order to use it to define the word bachelor. Again, I invite Con to look at Moore[1] and Wittgenstein[2] to clarify his thinking on these matters.


Con chose to put forward as rebuttals a selection of existing philosophies. I would like to bring to attention the fact that I am writing my own propositions and rebuttals and that I have limited space in which I can not in detail refute three major schools of thought.

Even under these circumstances I have provided enough evidence to render the rebuttals unsuccessful. A summary of my points:

  • Con is supporting viewpoints that he does not follow in real life. Before you charge me with some kind of variation of 'ad hominem'! I am just using this to point that his solipsist argument is purely theoretical and contradicts both mine and his experience of the world. He is talking about the solipsist view but he is living according to the view I presented in my opening statement.
  • Even if we take the solipsist argument as true (which we shouldn't as I have indicated), that does not disprove my point. It merely states that Logic can not achieve certainty and that is it. The only way out of that is for Con to provide an example in which certainty arrives from pure reason that does not need any experience or experimentation. Just to demonstrate further the impossibility of that task, I would like to point that even language is learned through experience.
  • Descartes doubt has the same bearing on my argument as the solipsist one. It just takes it to an impractical extreme. Regarding specific rebuttal, as Con is providing overviews of other peoples philosophies, I will point him to my own references (as provided) where he can be informed. The only argument that he provided was the dream one which I refuted pointing to research on “Lucid Dreaming”. Again remember that even if we can only be sure of our own existence that is not a rebuttal of my resolution but an extension of it to an extreme level.
  • Finally regarding a priori assumptions this is again just a reiteration of a particular philosophical argument without any actual argumentation. Nevertheless, I provided a rebuttal to keep things going. Con should choose one of his a priori statements and argue in its favor.

Con said:

“Knowing all this there can be no other vote but a negative today. Vote Con.”

I would say:

Judging from all that’s been written, there can be no other vote but a positive today. Vote Pro.”




[3] LaBerge, S. & Rheingold, H., 1990. Exploring the world of lucid dreaming. New York



AshleysTrueLove forfeited this round.
Debate Round No. 2


My opponent forfeited the round so there is nothing to argue. Furthermore, examining his previous post I was sad to realise that it was assembled in its totality by copy and pasting from his sources. This is extremely annoying as I actually spend my time rebutting his copy paste points. I understand that Con is really young but I would still expect an apology for his conduct and the reassurance that, if he is going to stay a member of DDO, he will from now on be aware of the rules regarding plagiarism and commit to a debate once he has started.

Needless to say, vote Pro.


AshleysTrueLove forfeited this round.
Debate Round No. 3
4 comments have been posted on this debate. Showing 1 through 4 records.
Posted by AshleysTrueLove 4 years ago
To Nur ab sal I went there.
Posted by AshleysTrueLove 4 years ago
I honestly thought he violated terms.. LOL i feel dumb
Posted by Nur-Ab-Sal 4 years ago
This is an interesting topic. I want to see what arguments Con makes.
Posted by THEBOMB 4 years ago
"Sissi is a cat
All cats have a tail
therefore Sissi has a tail"

What about the cat that got its tail cut off :P
2 votes have been placed for this debate. Showing 1 through 2 records.
Vote Placed by 16kadams 4 years ago
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Total points awarded:40 
Reasons for voting decision: FF
Vote Placed by 1dustpelt 4 years ago
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Reasons for voting decision: ff