Logic and Empiricism

It depends what we seek to answer.
What other reliable methods do we have of determining what is real and what is not? What is fact and what is fantasy?Faith, feelings etc. are so totally subjective and can be so totally sucsceptible to personal delusion that they cannot be treated as evidence for anything other than the conviction of the individual in question.The only reliable methods we have of evaluating an objecive reality are empirical and all the empirical evidence points to a naturalistic basis for life, the universe and all of it's workings including those same feelings of faith that cause some to believe that there must be more to it all than forces, matter and energy.Logical conclusions can be made from any premise, whether faith based or empirical, but when dealing with reality the conclusions made will only be as accurate as the premise is true.
For that reason conclusions based on, and backed up by, empirical evidence will always be superior to those based in faith.

When we use reason to deduce conclusions that have not yet been empirically detected we call these predictions.
However without the ability to then empirically test these predictions against nature I don't see how we can possibly establish them as facts.
This is, in my opinion, the key difference between true science and all the various forms of pseudo science that exist out there including creationism in it's various guises.Edited by Straggler, : No reason given.Edited by Straggler, : No reason given.

It all depends exactly how string theory were validated through experimentation and exactly how fundamental to the workings of the theory the whole multiverse idea really is.To take a better known example - Quantum theory and the collapse of the wave function - There are many that would say that this is strong evidence for the many worlds theory in some guise or other. The mathematics implies it. Wave particle duality and interference patterns can be explained in terms of it etc. etc. However even with this relatively (as compared to that for string theory ideas) strong evidence I would suggest that calling the many worlds interpretation of quantum theory as an indisputable 'fact' rather than a realistic interpretation would be stretching things for all but it's most ardent advocates.Predictions that require a particular interpretation to be true and then verification of these predictions are needed before the word 'fact' can be bandied around.Even then there will be those that dispute the interpretation so a body of evidence based on verification, prediction and corroboration with other established theories will be required before it can be held up as a theory to match evolution, big bang theory etc. etc. as effectively established facts.Such is the way of science.Edited by Straggler, : No reason given.

On that basis I don't think the argument as to the validity of the 2 possible conclusions could be definitively claimed either way.However should another theory (hypothetical - I have no such theory in mind), completely seperate to string theory, but equally reliant on branes to justify it's mathematics come along and be empirically verified independently of string theory - then the reality of branes as more than a mathematical construct would be independently corroborated and effectievly verified in it's own right.But I do think it would take something like that to settle the argument one way or the other.Without it the existence of branes cannot be considered scientific 'fact'

I am still not sure what your point is?In the case of either black holes or branes the mathematical interpretation used to predict their existence is exactly that - a mathematical interpretation on which predictions can be made.Only when empirical evidence is found can they become established scientific facts. Empirical evidence can, and often does, include detailed predictions of unknown phenomemnon that are based on the logical consequences of the theory in question i.e. branes in this case.
Branes themselves do not have to be detected directly for empirical evidence to be used to verify or refute their existence.
We did not have to witness the BB first hand to establish it as a scientific fact. Detailed predictions of CMB eventually nailed that one.This was true of black holes, for which direct empirical evidence does now exist, as you have already stated and it remains true of branes.If it really is the case that these branes are totally undetectable and that no predictive experiment can be done to indirectly verify or refute their existence then they will remain useful mathematical constructs that may or may not be describing a something prfound about the nature of reality.You seem to want a definite yes or no to a question to which the only viable scientific answer is that 'without more empirical evidence we cannot say either way for certain'.So what is your point regards branes and the OP regarding logic and faith etc???

Predictions based on branes are exactly what I was missing from my last post to Griz so thanks for pointing me in the direction of those.
I am not sure where exactly he is going with the branes argument specifically but there may be an interesting point in all of this.Lets take a hypothetical situation. Lets imagine that a ToE has been found. Quantum gravity explained, fundamental particles predicted and experimentally verified as a result of the new ToE. Holy grail in place and all is well with the world.
Lets imagine that the mathematics of our ToE suggests the existence of numerous empirically undetectable universes. This same mathematics is used for all sorts of practical applications and accurate predictive results in our own universe which establish it truly as a theory of everything.Fundamental to this mathematics is the existence of universes that have no practical effect on our universe.As you say In this sceanrioDo we trust the math and it's empirical results in our limited sphere of experience to conclude that the other universes must exist?Or do we deny their existence as fact on the grounds of lack of empirical evidence?I think this is what Griz is getting at with the Branes argument.

I too am a physics/maths undergrad who got happily sidetracked by the philosophy of science courses (all seems a very long time ago alas).
I agree that questioning the nature of reality beyond the 'that which works' mentality is interesting and worthwhile even if often frustrating and fruitless.So given that Nator has answered the question to some degree as to how far he would take reason alone in the search for truth - how would you relate all of this back to the OP?It seems that most of those with a scientific bent, including myself, see the deductions of reason alone as useful and potentially fruitful areas for prediction and further enquiry but are broadly sceptical of calling anything that is not ultimately backed up by empirical evidence of some sort, scientific 'fact'.

Well broadly I agree. Yes we do need input from someone coming from a faith based position in order to continue.
How far will those coming from a faith based position be willing to draw conclsuions on reason and logic alone without empirical evidence? How exactly does this differ from the empirically based and highly sceptical scientific viewpoints expressed above? Does logic and reason add anything to the faith based view? Do logic and reason stand in the way of faith at all?Any faith based takers?