# Deductive or Abductive?



## a mere housewife (Sep 28, 2006)

I had a question about 'deductive' and 'abductive' logic. A Nichiren Buddhist I have been having a sort of discussion with, claims that “Logic can, of course, lead to Christianity, given two presuppositions: that you’re using abductive, rather than deductive, reasoning (seeking explanation for an accepted/observed truth, rather than seeking truth through a series of observations)”. 

In reply, I said: "If you want to start seeking truth without accepting your experience than you will never prove that you even exist. Not only do we accept experience but we accept certain a priori logical principles by which we organize it. You do the same."

And he replied: "But I DO accept my experience. I only accept it as incomplete. That’s a pretty significant difference you seek to erase with your semantic gamesmanship.
Agreed. And my a priori logical principles have served cultures other than ours rather well, and have begun to serve ours where our own systems have failed (per my previous example re: alternative medicine). Yours, conversely, have given us Western civilization. I see no victor (barring revelation by the Holy Spirit, of course)."

I am not sure why he thinks that we believe our experience is 'complete'? Would he have gotten that idea by somehow twisting from Plantinga because I have said no such thing? -- I think one article by Plantinga may be all he has read of presuppositional apologetics, & he thinks him a 'lame dog philosopher'. Which makes me laugh.
He denies non-contradiction, and wants to say that denying it is basically another way of doing logic. Which makes me laugh, of course.

Besides the question about our experience being complete, I was wondering what exactly is the difference between 'abductive' and 'deductive' logic-- isn't he misunderstanding, at least if he thinks deduction does not lead to Christianity? And how best should I phrase an answer to him about this?

[Edited on 9-29-2006 by a mere housewife]


----------



## Civbert (Sep 28, 2006)

> _Originally posted by a mere housewife_
> I had a question about 'deductive' and 'abductive' logic. A Nichiren Buddhist I have been having a sort of discussion with, claims that “Logic can, of course, lead to Christianity, given two presuppositions: that you’re using abductive, rather than deductive, reasoning (seeking explanation for an accepted/observed truth, rather than seeking truth through a series of observations)”.



I'm not sure of your definition of deduction. Also, abductive logic is ultimately going to be inductive or deductive in form. It does not matter what direction you seek to go (premises to conclusions, or start with a conclusion and determine premises) - it will have to be either deductive (conclusions follow necessarily) or inductive (conclusions possible follow).



> _Originally posted by a mere housewife_
> 
> He denies non-contradiction, and wants to say that denying it is basically another way of doing logic. Which makes me laugh, of course.



Hopeless. If he denies the law of non-contradiction then there is not reasoning with him. He can always fall back on irrationalism. 



> _Originally posted by a mere housewife_
> 
> Besides the question about our experience being complete, I was wondering what exactly is the difference between 'abductive' and 'deductive' logic-- isn't he misunderstanding, at least if he thinks deduction does not lead to Christianity? And how best should I phrase an answer to him about this?



Deduction itself can not lead to Christianity or any other conclusion. You have to presume something to conclude Christianity is true. So it starts with whatever axioms that are chosen. Whether it's call abduction or deduction or induction does not matter.


----------



## Civbert (Sep 28, 2006)

Some might say abduction is the reverse of deduction. That's fine. It's still Aristotelian logic. The process of taking a conclusion and determining the premises that prove the conclusion was exactly how Aristotle described the proper function of logic.


----------



## a mere housewife (Sep 28, 2006)

Thanks Anthony.

The first definitions quoted were his-- basically I understand you to be saying that deduction (or at least 'properly functioning logic') is the process of conclusions that follow necessarily, whether you start at one end or the other; so the 'you can't be using deduction because your using abduction' statement is a false alternative, at least as far as it tries to present that the conclusions of abduction are more suspect?

Would you say that accepting our experience as it comes to us and our a priori methods of understanding it -such as non-contradiction- for the premises, and deducing from that in a _consistent_ manner would lead to the conclusion that only Christianity is rational? For instance it's impossible to explain our experience and understanding of relationship consistently without being Trinitarian? -because I do think that last, but I am trying to reconcile it with the fact that no one does accept their experience neutrally: our experience comes to us in a framework of presuppositions.

[Edited on 9-29-2006 by a mere housewife]


----------



## MW (Sep 28, 2006)

Deduction requires a consistent system; else variables will be produced from the premises. I also think deduction requires predication and predication requires the verb to be, which implies existence. For universal predication to be possible a universal existence is required. One cannot arrive at an infinite, eternal and unchangeable truth without an infinite, eternal and unchangeable Mind which can validate that truth in all places, at all times, and under all conditions.

[Edited on 9-29-2006 by armourbearer]


----------



## a mere housewife (Sep 29, 2006)

Mr. Winzer, thank you. I think the consistent system part would definitely go against what he wants to say (that logic and reason, as well as morality, are changeable and do often change) -- but trying to anticipate his response to 'universal existence' I think he might say that is the 'Tao' or whatever he calls his conscious matter. I don't really understand his position (and this is where I originally asked him about contradictions) because he wants to say that all is a great nothing, that this great nothing is 'god', in which the highest form of 'existence' is simply to go out: the universal consciousness which I share with a drop of water is a divide from this void. (It reminded me of a Father Brown story where they ask a Hindoo in a mere politeness what he wants, and he says 'Nothing' three times. Father Brown says, as they are walking away- "If he were a Christian, he would have wanted _something_.") Obviously it would be contradictory for him to claim universal existence when all is nothing- the terms of that phrase are a contradiction, and there can be not even the delusion of existence if one were to to try to be consistent with it; but he claims immunity from contradictions -- while at the same time arguing internal consistency for his beliefs?

[Edited on 9-29-2006 by a mere housewife]


----------



## Civbert (Sep 29, 2006)

> _Originally posted by a mere housewife_
> Thanks Anthony.
> 
> The first definitions quoted were his-- basically I understand you to be saying that deduction (or at least 'properly functioning logic') is the process of conclusions that follow necessarily, whether you start at one end or the other; so the 'you can't be using deduction because your using abduction' statement is a false alternative, at least as far as it tries to present that the conclusions of abduction are more suspect?


Yes. It's a matter of definition, but as I thought about it later, I'm not sure abduction would always be deductive in form. I suppose it could be inductive also. It sounds a lot like the scientific method (which is essentially inductive). Natural science takes observations and then through hypothesis testing, tries to determine the cause. So I suppose abduction could be either inductive or deductive in form - where deduction and induction do not specify what you start with (the conclusion or the premise, the cause or the effect) - the difference is in the relationship between the conclusion and the premises. Wherein abduction is specifically a matter of starting with the effect or conclusion, and tries to determine the necessary or most probable cause or premises. 



> _Originally posted by a mere housewife_
> 
> Would you say that accepting our experience as it comes to us and our a priori methods of understanding it -such as non-contradiction- for the premises, and deducing from that in a _consistent_ manner would lead to the conclusion that only Christianity is rational? For instance it's impossible to explain our experience and understanding of relationship consistently without being Trinitarian?


 No. I don't think our experiences can only be explained by Trinitarian Christianity. I think it is the best explanation. I know of none better. It's definitely a "very good" inductive argument, but it is a formally invalid deductive argument. There's still the small possibility that the argument is false because the premises are unprovable. 



> _Originally posted by a mere housewife_
> 
> ... -because I do think that last, but I am trying to reconcile it with the fact that no one does accept their experience neutrally: our experience comes to us in a framework of presuppositions.
> 
> [Edited on 9-29-2006 by a mere housewife]



Yes. It is the presuppositions that frame or experiences, but they also determine our understanding of experience. If one does not presuppose the law of non-contradiction - one can not possible justify any univocal meaning of language or possible knowledge. 

And maybe a Buddhist would simply uncertainly deny there is any univocal meaning or knowledge. He might say that as far as he can tell, there is no knowing anything. As long as he realizes that he may not be able to justify that as an assertion - he can still do believe it. We can not deny him that presupposition. 

We can point out that he is caught in a never ending but self-referential consistent feedback loop of meaninglessness. He can say it may be true that it may be true ... (insert countless "it may be true")... that it may be true that he may not know anything. He can never truly exit the loop. Inductively and presupposition-ally, he will have a 99.99...% true statement as long as he never claims it is 100% true. From our presuppositional position, this is absurd. But from his perspective, who knows? Maybe it is, maybe it's not, maybe. It would not be valid to even put it in the form of a proposition. It would be meaningless - but only to those who assume there is meaning. 

It is a tautology to say there is meaning. We can not get away from our presuppositions, and our presuppositions determine what is valid and true. Ergo, for us to be correct about Christianity is only by the grace of God (another self-referentially but valid tautology).


----------



## Civbert (Sep 29, 2006)

> _Originally posted by a mere housewife_
> ... because he wants to say that all is a great nothing, that this great nothing is 'god', in which the highest form of 'existence' is simply to go out: the universal consciousness which I share with a drop of water is a divide from this void. ...


 This he can not assert - he can speak it and wonder if it is true. 



> _Originally posted by a mere housewife_
> 
> ... Obviously it would be contradictory for him to claim universal existence when all is nothing- the terms of that phrase are a contradiction, and there can be not even the delusion of existence if one were to to try to be consistent with it; but he claims immunity from contradictions -- while at the same time arguing internal consistency for his beliefs?



How ironic! His system does not allow for any claims since he denies the law of non-contradiction - even the claim of consistency would be inconsistent - and yet he could never know that from within his system because his system can never justify knowing any proposition. Externally, from a presupposition that includes the law of contradiction, we can see his system is incoherent but he can never justify knowing this.


----------



## JohnV (Sep 29, 2006)

Heidi:

I have a couple of questions for you. Are you challenging him, or is he challenging you? Who is engaging who? 

If you are engaging him, then I would like to ask, Why? Are you trying to convince him? Or does he have a particular problem that you are trying to help him with? Or do you feel burdened somehow to evangelize to this particular person?

If he is engaging you, is he asking you these questions out of an opportunity for converstation? Or is he burdened to evangelize you? Or is he just trying to rub you nose in your belief? 

By the things that you have said so far, he has taken on an "unassailable" position in order to engage you in discussion. That is, he can say whatever he likes without the burden of accountability for it, since he denies any tie to reasonableness by denying the law of contradiction. Without this law of thought, one cannot reason truly. The answer to this kind of 'reasoning' is generally to know and use the unassailability of the Christian position with great care. It's the ol' Ravi Zacharias trap, if you will, forcing him into the contradictions, the unreasonablenesses, of his own views. 

If you get caught in the trap of putting everything into the categories of presuppositions, then I think you will always be susceptible to his ploys. It depends on what your focus is. If you are the kind that is satisfied with, "I guess I showed him" type of argumentation, then go ahead and use it. But it won't interest me how you made out. But if your attitude is how much, if at all, he was open to the Spirit's urgings, whether for the present or for the future of his own life, then you need to draw a clear distinction between your belief as a Christian and Christianity proper. Your belief, however good it may be, is not Christianity itself, and is not deep enough to answer all his questions. And you need to beware that your own failings and inconsistencies in faith in no way nullifies the truth of Christianity. It cannot hang on you or your personal presuppositions; it must hang on the Bible. 

In your conversations you may well come across arguments or tenets that you yourself have been weak in, or that you did not hold to according to the degree that you have propounded it to another. So you need to be aware that you are talking to and convincing yourself as well at times. I know this sounds strange, but the Spirit does work this way in the hearts of people who are sensitive to the difference between the weakness of their own presuppositions, knowledge and faith and the strength and totality of the Word and Spirit. Do not compare "my presuppositions" with "your presuppositions", because the Spirit is interested in leading both of you into truth, which neither of your presuppositions are adequate for on their own. You are doing the Spirit's work, not your own; and it is He that convinces, not you. You are an agent, a means which He uses for Christ's kingdom. 

More to the point of your question, see if you can get him to define what abductive reasoning is. Make yourself well versed in the difference between inductive and deductive reasoning, and force him to one or the other. Then when he has begun to make a commitment to one or the other, then ask him how, in his belief system, he can make a commitment to it without the law of contradiction. The trick to this is to recognize his use of the law of contradiction to assert his own system of abductive reasoning, (which does not really exist at all as a defined system, but is quite a rampant system nonetheless, utilized even by Christians at times. Its a new name to me, but is still the same old pantheistic trick.) 



This post puts me at 2600. For some reason it bothered me to be at 2599. So I wanted to be careful where and to whom I posted. I have changed since last summer when my appeal came before the 73rd General Assembly. I thought I would be posting as much, but more pointedly, but instead I find I am posting hardly at all. So, since it was you, Heidi, I thought this was good time to get this one post in. 

By the way, this summer has been a good summer, in that I have been doing more again, and getting involved in family things again. I still tire (get exhausted, actually) a lot, but seem to have more energy for at a few hours. I played guitar for the church picnic, for whoever came around to listen. There seemed to be a parade of people all afternoon, of every age group. I dropped from exhaustion by the time I got home, but I haven't had so much fun for a long time, talking to people about their favourite music. I still get bad days, but I seem to have more good days lately. Is it progress? I don't know, but I'll take it.

[Edited on 9-29-2006 by JohnV]


----------



## a mere housewife (Sep 29, 2006)

JohnV, I'm so glad you're doing better this summer: that is very happy news- and thanks for your comments.

Actually he challenged me first, on a friend's site, when I was replying to something an atheist had said. I promised to clarify something he wanted to know about in my comments and wound up just posting a quote and a link to an article by Plantinga (thus his contact with Plantinga). We went back and forth about that a little: though really the whole point of it had not been so much to argue with him, as to clarify a point in my argument against the atheist. This time I fear it was my own fault: he hangs out on my blog and I addressed some things he had said elsewhere, linking to our previous conversation.

I have actually bowed out of that discussion this morning, because I am not trying to simply argue him down: I don't expect to be able to do that. I tried again to point out to him the unreasonableness of denying non-contradiction, which he has to do because his views about the nothing/something are so contradictory-- but he won't see it, though claiming to be very logical and deductive. If you want to read through it (or engage him-- he is perfectly ready to be engage, or to himself engage others-- he doesn't like our 'narrowness' and I can only guess that he is either very bothered by the claims of Christianity and finds it necessary to attack them, or is trying to convert people-- I vote for the first) you can link to my web page below and go into the 'apologetical' section-- he is the top two posts there.

I hope you stay well. Happy 2,600th.


----------



## JohnV (Sep 29, 2006)

No thanks, Heidi. If he's interested in or challenged by Christianity, as I am, then that's another story. But if all he's after is some feathers in his cap, I really don't care how many feathers he has: they don't amount to any value in the end. 

If someone shows that the Spirit is working him towards faith, then I'm all ears. I want to listen in order to know how he thinks and why he thinks that way. That's my own self-examination process also. After that we may both be challenged by what the Word of God says to us, and how we are to comply with revealed truth in order to understand truth ourselves. I'm interested in conversations and interactions that benefit each of us toward sanctification and holiness, perhaps justification for the other. I'm not interested in my own views, as it is my hope to cast them off in favour of embracing only truth; so I'm hardly going to parry and thrust with mere words and points of view. 

I never got into this blogging thing. I wanted to for while, so that I could speak out to whoever wanted to hear about the ordeal I went through and what these things have to do with Presbyterianism as a whole. I've have in my possession an almost endless cache of evidences, statements made, direct references, actual live examples, and on and on, that I think everyone needs to know about. But I decided that I should let it rest. If I am allowed to leave the Presbyterian church on the terms I've laid out, then I'm just going to leave them and not say a word about it anymore, to the degree that my responsibility allows. That means that my interest in blogging, as well as public discussion boards, has decreased greatly. 

So I'm hardly going to get involved in a discussion on the internet with some internet theologian. You may notice that there's very little accountability in such venues. The only real accountability is that previous posts are on record, and may be compared for consistency. But otherwise, there is no one to answer to for personal views; anyone can believe anything he wants, and call it whatever he wants. Someone may claim even to be Reformed, and to adhere to the Reformed standards, and yet say all kinds of things that are completely at odds with it, setting up new "necessary doctrines", which are not expressly stated in Scripture as our Reformed standards insist should be the case. I'm sticking to discussions with real people at real meetings in a real church, as much as I can. This place is a good place to interact, to ask questions, to seek information, to pick each other's brain, and so on, but it is quite clear that true accountability can only be set in actual and full communal settings. What you did by cutting off discussion, when it was clear that the end in view was not honourable, would be just what I would have done in a similar situation.

[Edited on 9-29-2006 by JohnV]


----------

