I would like to suggest that when two (or more) men (or women) come together to express their thoughts, that there are (perhaps unspoken) rules for this attempted communication. One is that they both speak the same language. Imagine an Ethiopian speaking with an Inuit: they may exchange sounds but they exchange no meaning. Whatever meaning they will exchange will come from body language, a "language" they both (imagine they) understand. But I will not belabor the point, if you're not with me this far, there's no point in your reading further. Second, they must both speak the same language in another sense: that is, they must have a shared understanding of the meaning of the words they use to convey their meaning. If they don't, they will agree where they have differences and they will argue over commonly-held beliefs. And in the end they will imagine they understand their fellow whereas they do not. And unless a specific source for words' meanings is agreed upon beforehand, they must use words in their dictionary senses.
The other night, after a lecture about Einstein in Berlin, an audience member suggested that scientists ought to take moral responsibility for their actions and that if they did, there would be no weapons of mass destruction. The response was that they do make moral decisions: when a German scientist during WWII agreed to work for his government, he believed he was working for the good side. When an Iraqi scientist helped Saddam, he thought he was helping the good guys. Of course, it is possible for there to have been strong elements of coercion. But the point the man was making was that scientists do not typically consider morality (good and evil) in their decision-making. The response was that they do, it is just that their standards of good and evil are local, not universal. This aspect of the disagreement between the two was that they had differing thoughts about the objectivity or subjectivity of good and evil. Another point raised by the first gentleman was that rational people perforce make good (not evil) decisions. That is, if these scientists had only thought rationally (or scientifically) they would not have made the decisions they made. In this case, the man was collapsing reason with ethics; he was suggesting that the rational human was an ethical human. While it is pleasant to imagine that all reasonable men are men of good will, and they may be, but they will not necessarily side with the same national forces: indeed they are likely to side with the nation of their birth.