Does inductive reasoning lead to knowledge?
in [Logic]
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From: dorayme on 14 Dec 2009 20:02 In article <daniel_t-DEB827.19410614122009(a)earthlink.us.supernews.com>, "Daniel T." <daniel_t(a)earthlink.net> wrote: > dorayme <doraymeRidThis(a)optusnet.com.au> wrote: > > "Daniel T." <daniel_t(a)earthlink.net> wrote: > > > dorayme <doraymeRidThis(a)optusnet.com.au> wrote: > > > > "Daniel T." <daniel_t(a)earthlink.net> wrote: > > > > > > > > > .... all deductive arguments rely on either arbitrary > > > > > definitions or inductive arguments. > > > > > > > > > > > > > How so? > > > > > > Every sound deductive argument requires true premises. > > > > Soundness in the sense of validity of argument has nothing to do > > with the truth per se of the premises or the conclusions. > > Soundness and validity have two different meanings. A "sound" argument > requires true premises, a "valid" argument does not. OK, that is fair enough. I am never sure who knows what i this usenet group or how quite they are using words. This leaves your claim that all deductive arguments rely on arbitrary definitions or inductive arguments. Be interested to see how you establish this. -- dorayme
From: Daniel T. on 14 Dec 2009 20:23 dorayme <doraymeRidThis(a)optusnet.com.au> wrote: > "Daniel T." <daniel_t(a)earthlink.net> wrote: > > > My basic point is that for all sound deductive arguments, there must be > > a set of true premises. These premises are eather deductivly true (which > > leads to a circle,) true by definition (as in your example,) or > > inductivly true. > > I doubt if a reasonable belief in a proposition has to fall into one of > these three categories. > > It can be reasonable to believe something because there is nothing else > one can think of that explains as much. This is not obviously something > that can be squeezed into these straight jackets. The way you know that what you are thinking of explains so much is through inductive reasoning. It has always explained things in the past. Maybe if you give an example? > Not only is it not the case that it looks forced to think of explanation > as induction from cases but there is the question of statements which > are not "true by definition" (using your terms) but which are impossible > to deny, such as first person statements about how things *seem* to the > person. How things seem tells us nothing about how things are, the best we can do is wrap them up in inductive arguments. "That crow seems black" is not an argument of any sort. "I've asked 5 people who saw the crow, and they all have said that it seemed black." is an inductive argument. Again, maybe if you gave an example? I'm certainly willing to modify my position. Can you present an argument (i.e., syllogism) that doesn't fit the assertion I made?
From: Daniel T. on 14 Dec 2009 20:27 dorayme <doraymeRidThis(a)optusnet.com.au> wrote: > Patricia Aldoraz <patricia.aldoraz(a)gmail.com> wrote: > > On Dec 14, 12:39 pm, John Stafford <n...(a)droffats.ten> wrote: > > > > > > In deductive reasoning, arguments that depend upon how things "seem" is > > > immediately weak so the argument is not sound. Discard it. That's how it > > > works. > > > > That is how *what* works exactly? > > There are various types of weaknesses in arguments, one being the > premises do not support the conclusion, the other being the conclusion > is too obviously contained in the premises, another would be the > premises are false. None of these are sound arguments though. My statement was regarding sound arguments. > Arguments that depend on how things seem are not immediately weak in the > sense that they *must* have false premises. They are not necessarily > weak in the sense that they *must* lack the entailment relationship. > > A patient tells his doctor: > > "I seem to see a fog when I first open my eyes in the mornings. > > "There is never any fog at this time of the year. > > "Therefore, there is something wrong with me" The second premise relies on inductive reasoning (So far no fog has been around at this time of year.) The above is an argument that depends on inductive reasoning. > There are even trivial but perfectly valid ones like: > > "I seem to always think Mr. X is a bachelor! > > Therefore I always seem to think Mr. X is an unmarried man." "A bachelor is an unmarried man," is true by definition. So this argument too fits my claim.
From: Daniel T. on 14 Dec 2009 20:31 Patricia Aldoraz <patricia.aldoraz(a)gmail.com> wrote: > On Dec 14, 3:32�pm, M Purcell <sacsca...(a)aol.com> wrote: > > On Dec 13, 4:56�pm, dorayme <doraymeRidT...(a)optusnet.com.au> wrote: > > > In article <daniel_t-D773AE.18584313122...(a)earthlink.us.supernews.com>, > > > �"Daniel T." <danie...(a)earthlink.net> wrote: > > > > > > My basic point is that for all sound deductive arguments, > > > > there must be a set of true premises. These premises are > > > > eather deductivly true (which leads to a circle,) true by > > > > definition (as in your example,) or inductivly true. > > > > > I doubt if a reasonable belief in a proposition has to fall into > > > one of these three categories. > > > > > It can be reasonable to believe something because there is > > > nothing else one can think of that explains as much. This is not > > > obviously something that can be squeezed into these straight > > > jackets. > > > > > Not only is it not the case that it looks forced to think of > > > explanation as induction from cases but there is the question of > > > statements which are not "true by definition" (using your terms) > > > but which are impossible to deny, such as first person > > > statements about how things *seem* to the person. > > > > Yes, a proposition must be imagined first. And since there may be > > an unimagined proposition that contradicts the known, I suppose > > the certainty of an assumption is limited by our imagination. > > I think there is a misunderstanding. The point is not about how a > proposition seems but rather that how some things seem to humans has > traditionally been argued to be incorrigible, not able to be > doubted, not able to be imagined wrong. > > It has been argued that my seeming to see a red patch before my eyes > is something that needs no argument to establish, there is no > evidence beyond the act of it seeming so to me that could count as > being evidence for it. That rules out inductive reasoning being the > justification. And there is surely no deductive argument that brings > us to the proposition. > > If such statements about my experience are neither deductively > arrived at nor inductively arived at, it does not augur well for the > idea that there is some circularity in a deductive argument that > contains such premises. Maybe if you presented such an argument I could asses it. "I seem to see a red patch" is not an argument. It may be that I have to include qualia as well as induction and definition.
From: dorayme on 14 Dec 2009 20:43
In article <daniel_t-3D392A.20275414122009(a)earthlink.us.supernews.com>, "Daniel T." <daniel_t(a)earthlink.net> wrote: > > Arguments that depend on how things seem are not immediately weak in the > > sense that they *must* have false premises. They are not necessarily > > weak in the sense that they *must* lack the entailment relationship. > > > > A patient tells his doctor: > > > > "I seem to see a fog when I first open my eyes in the mornings. > > > > "There is never any fog at this time of the year. > > > > "Therefore, there is something wrong with me" > > The second premise relies on inductive reasoning (So far no fog has been > around at this time of year.) The above is an argument that depends on > inductive reasoning. You are concentrating on the possibly "inductive" premise whereas I thought you were meaning that all the premises must be either inductively or deductively arrived at in their turn. I was disputing this. You did say that you thought that everything we know about reality is ultimately inductive and I was pointing out that it is not obviously so. It may be under some definition of inductive I am unaware of? I *really* do not know what you have in mind, unless it is the reasonably well defined and what rather looks to me like non-reasoning that goes "x has happened n number of times therefore it is likely to happen again". I am completely with Hume on this. Though, unlike him, I don't think this is how we really reason. -- dorayme |