Adam's Answer
1. If it could be proven a collective conscious exists i.e. if all thought and vibrational information in the universe was somehow connected via a single source, then a truth would be objective and undeniable as it would be true to everything via the single source.
2. If a collective conscious does not exist and everything is not connected then an individual truth would be true to only the individual, as its personal truth could only come through its own experiences and no individual experience could be shared. Hence an individual truth is only how it is seen by the individual. Therefore no objectivity due to individual understanding of any given object or event. Makes sense?
Would an alien specie born of completey different circumstances agree?. I don't know because we have nothing to compare our human truths with. Hence the dilemma of a truely definate answer.