Word for theories that cannot be disproven ?

Is there any word for something which cannot be disproven. E.g. I want to say: "Vedas were written around 10000 BC". This has some proof but not certain, but it cannot be disproven. What should be the one word for this?

Solution 1:

"word for something which cannot be disproven"

One might describe such an idea as being unfalsifiable, although for a non-scientific usage the layman's definition of theory that the OED gives could even be used.

If the idea has not yet been tested it could be a speculation, though you may want something that suggests a little more thought has gone into the idea if it has "has some proof but not certain".

Dictionary.com says a hypothesis is

"a proposition [...] accepted as highly probable in the light of established facts"

which might fit your example quite well.

Or: Conjecture.