While there are other things that can fill in the above mentioned blank, I think that you both are being to quick to pass judgement on abductive reasoning. Although it may not be as rigorous as other forms of logic I think that it is viable and should not be tossed aside.

In the question of whether or not God exists I think that we have a real issue, namely that atheism (god does not exist) is nearly unfalsifiable. Pretty much any set of data can fit into the atheistic theory (again, that god does not exist) no matter how improbable. That leaves us with tools like abductive reasoning to come to a conclusion even if it is not a solid as a conclusion that you would get from deductive reasoning.

I don't maintain any claims I made re how atheists arrive at their conclusions. You are right there.

As far as my own beleifs it is difficult to say how much of what I believe is axiomatic (in relation to Bunny's query) /a priori and how much is what I conclude.

Is this not equally true for Theism? I can't help but think back to a thread you started where you asked what a person would expect to find in a universe where God exists (I think thats it, correct me if I'm wrong.)

What ended up happening, as I remember, is the atheist invariably thought the universe as is was evidence for no-god while the theist thought the universe as is was evidence for god.

It seems to me that we can use what we see in the universe to justify whichever viewpoint we hold.

"Reason for God" is a good book. It is worth the read for sure. My only frustration is he really glosses over many topics. He doesn't dig deeply into evolution or the problem of evil or why God permits slavery etc. He touches an all the hot topics while not really digging into any of them.

Regardless still a good read and he makes some good points. He quotes Alvin Plantinga and other Christian thinkers/teachers which makes me rather want to read the work of those guys instead. Keller is a pastor so his goal I think is just to allay some of the fears the average person has, he is not aspiring to be WLC.

I guess for me to listen to debates with WLC and Plantinga and then read Keller his work seems shallow. Keller is still an amazing guy who I have a ton of respect for. Also as you mentioned he is very empathetic and a good speaker

Without getting into the issues that I had with that thread, I would agree that theism can equally fit into most sets of data.

Which is exactly why we need to turn to tools like abductive reasoning to come to some sort of conclusion. When looking at the evidence holistically what explanation best fits. When one does this I think that theism is the clear winner, but of course that's why I am a theist

I wasnt quick to dismiss it at all. Granted it was fifteen years ago, but I did actually study logic at university, remember. It has something meaningful to say, but not anything particularly useful when it comes to testing beliefs (which is what I was speaking about).

Furthermore, we can claim it is the result of "abductive reasoning" rather than bias.

The claims are only empirically relevant if there is some distinguishing experiment we could perform.

You've got that backwards.

So bear with me here, I am unfamiliar with abductive reasoning and had to look it up.

The sample wiki gives is this:

The Lawn is wet
If it rained last night
Then it is unsurprising the lawn is wet

Would this form of reasoning (for you) put into the context of coming to the conclusion that god exists, look like this?:

The universe exists
If there is a God
Then it is unsurprising the universe exists

If so, I go back to my previous post, just replace "If there is a god" with "If there is no god."

Am I off base here?

Yeah, been there too - it's quite troubling to come to the realisation that you are one of those stupid people. :/
When I claim to be a strong atheist, people generally take that to mean a rejection of an infinite number of unspecified potential Gods. Personally, I take a similar stance to yours here. I think atheism is defined with respect to theistic claims - by stating that no gods exist, I mean that nothing a theist is actually meaning by the word "God" exists.

Not really.

Abductive reasoning is poorly named, in my view. It gives the impression that it's a way to proceed from premises to conclusions in a similar way that we do with inductive or deductive reasoning (ie the good kinds).

It's really a place to start. We look around, think of some potential explanations for the data we collect and then pick what seems to be the best explanation - that's the abductive reasoning part. After that, the real work of justifying a belief begins - we go and test it empirically. It has been characterised (somewhat unfairly, I suppose) as "just having a guess". It's an important first step in the scientific method (since otherwise we cant get started as we have no way to select which theories/propositions to test).

One way to see its problems as a standalone process, is to realise that it is logically equivalent to the fallacy of affirming the consequent. The deductive (invalid) form would be:

If there was no God we would expect to see a world with suffering
We see suffering
Therefore there is no God

The "abductive" argument is essentially

We see suffering
One explanation is that there is no God
that seems most reasonable to me

That' pretty much the way it seemed to me, but I thought there may have been more to it than that... I'd be interested to here why Jib believes this to be a path to theism.

I'm not the most polite about abductive reasoning (that and a fad for "hidden premises" used to really bug me back when I read about this stuff).

I think it's a whole bunch of dodgy nonsense, personally - a mildly interesting comment on the scientific process blown out of all proportion. I believe it has some applications in AI research - but it's not about finding truth, it's about giving an algorithm a way to choose a starting point (I know far less about this, of course, but I feel obligated to point out that abductive reasoning does actually have some uses).

So would Occam's Razor be an example of abductive reasoning?

No, that would be a heuristic principle, guiding our abductive reasoning:

I think that we the best way to look at this is by an example of something that you would both agree with the theory. The theory of common decent is not much more than abductive reasoning and shows how useful abductive reasoning can be. The evidence for common decent can very well fit into other theories and you cannot directly test the theory moving forward as it is about what happened. You cannot use deductive reasoning or anything else more rigorous on the theory.

I will start there and see why you believe that common decent is not a product of abductive reasoning.

It's (potentially) involved in how one may choose to prioritise the various competing explanations in order to select "the best", yes.

I've also seen it described as inductive - I daresay there are arguments either way.

Some kind of "leap of faith" is required to do or think almost anything in the real world. Finite creatures can never fill in all the gaps left by their observation and reasoning powers. That is very different from a "blind leap of faith". The Bible never advocates a blind leap.

Well, but common descent has a scientific basis. Things like the similarity of our DNA, the chromosome 2 discovery etc have all given us confidence that common descent is the best explanation to how humans began.

What does the existence of God solidly have behind it from an empirical perspective?

We do think alike about some things. This is exactly my problem - not abduction per se, but calling it "reasoning". It's very seductive because it can lead one to think some kind of logical certainty has been achieved when all you've really done is state a kind of "guess".

Reasoning is a process - deduction has rules that when followed achieve certainty. Induction has rules (the scientific method, for instance) that when followed achieve knowledge about the natural world. Abduction isn't a process and has no rules. Why is something "an inference to the best explanation?" To explain that you have to use the other methods. Christianity is the best explanation of reality because ... and here fill in with the theistic arguments.

I think abduction is fine, even essential, in the knowledge process, but it is not, in itself, a reasoning process.

“One finds in this subject a kind of demonstration which does not carry with it so high a degree of certainty as that employed in geometry; and which differs distinctly from the method employed by geometers in that they prove their propositions by well-established and incontrovertible principles, while here principles are tested by the inferences which are derivable from them. The nature of the subject permits no other treatment. It is possible, however, in this way to establish a probability which is little short of certainty. This is the case when the consequences of the assumed principles are in perfect accord with the observed phenomena, and especially when these verifications are very numerous; but above all when one employs the hypothesis to predict new phenomena and finds his expectations realized."
-Christoper Huygens "Treatise on Light"

More here: http://faculty.arts.ubc.ca/rjohns/ibe.pdf

But what you are doing is taking data and saying "based on this it is reasonable that common decent occurred." The data could in fact be interpreted differently as is seen in the creationist vs evolutionist "debate".

You're misunderstanding my objection. I do think it was a product of abductive reasoning. After that - we went out and tested it via clever experimental design. I wouldnt accept it if some guy said "Hey, I've come up with this! I cant think of anything better, so let's go with it."

As Sommerset points out, the compelling case for accepting it comes afterwards. There is DNA evidence, there is broad explanatory power. We wouldnt know what to look for without starting somewhere - but the fact we can come up with a starting point (and name it something impressive like "abductive" and strengthen it's appeal with the word "reasoning") is no reason to deem the explanation a good one.

No, I accept that. (I didnt actually find the notion of trusting God to be impossible - just unpalatable).

Crucially, the abductive reasoning happened before DNA was known about. That's why the discovery was so compelling.

Going back after the fact and 'back-filling' some hypotheses 'abductively' isnt valuable at all. Data used to formulate a theory cant be used to test it.