But what if there really is a spirit world? If there is (and I believe there is) it would be perfectly rational to say "a ghost did it". What defines a rational or irrational explanation depends on the person's perspective.
Interesting! Just before I get into this, i just want to say I am quite interested in this as a debate, but if at any time you feel I am overstepping a line or being too insistent please PM and I will apolgise and drop the subject. i realise that people's personal beliefs are important and sacred, and I am replying to share mine, and not attack those of anyone else. That said...
It would be perfectly rational if there was indeed a spirit world. I happen to believe there is not, but if it can be proven that there is, that would change my belief. I think things rest on 'reasonable proof'.
For example, if I expose a material, say copper, to flame, the copper will increase in temperature. The molecular structure will expand as it is heated. It will always happen if you use the same copper and the same temperature flame. We can infer that flames give off heat, that the copper is absorbing that heat, the heat expands the material... and we have sufficient 'reasonable proof' to say we 'know' these things.
Now, I avoid and reject all philosophical rebuffs on this in terms of "Ah but what if we are all brains in jars" and other such stuff. If we are, we have more to worry about.
So 'reasonable proof' to me is the result of a repeatable experiment which yeilds the same results, and a hypothesis (preferably more than one) which we can then test to see which is most likely.
What defines rational is that this model, this approach, has served us very well in obtaining knowledge. I wouldn't state that there is such a thing as a gravity particle, because we have no evidence that it exists. Sure, people may have assumptions that it does, there may be some evidence, but nothing like reasonable proof.
Similarly if I say "that happened because of the magical powers of the Invisible Pink unicorn!" people won't assume I am rational. Even if it fits *my* perspective and makes sense, where is my proof? My worldview must be supported by evidence. let me move to a more practical example:
A man sincerely believes he is being hunted by the CIA, because he knows about the experiments they carry out on people, and about the aliens that have been visiting the earth. Every phonecall is a potential spy tring to track him down, every news story a coded message. That's his belief.
Society would deem this man irrational (probably paranoid, maybe suffering a mental illness) unless he could show us documented evidence of these claims.
That same man would be deemed rational if he could point out real CIA agents following him around, show us un-faked photographs of aliens, and show consistent cyphers that explain the coded messages and tie these messages to real world events.
In my opinion, rationality it is not quite perspective, but evidence which causes the majority of people to agree on the same perspective.