Donald Trump constantly contradicts himself and therefore cannot be trusted
No politician can be trusted that is a simple truth of politics.
Time travel is impossible.
A time traveler coming back now could very well cause a paradox. They could know that no time travelers came back to now and if they did that would cause a paradox. Or some government may steal the time machine and use it to their own purposes which would cause a bootstrap paradox.
There was never a universal language.
There can be a Universal language but there will be different dialects and that is an arbitrary line to draw. Because in old English "world" looked like* In modern English it is worlds singular and worlds plural. So is that considered 2 languages or 1 with different dialects.
Marijuana usage is harmful
There is harm if the smoker does not have a fully developed brain which occurs at about the age of 25.
It is dangerous to be looking for aliens
It is dangerous to have physical contact because there will be diseases on other planets but finding aliens is good the species of both our worlds can leave each other alone. So we do not wipe each other out with diseases.
There is no justification for war
There is always justification for a nation defending its sovereignty from an invading force. And for invading there is a chance that the country needs a particular resource and invading is the best way to gain access to that resource.
The chicken came before the egg
Eggs were a form of breeding a long time before chickens. So a better way to phrase this question is "What came first the chicken or the chicken egg" if that is what the question intendeds to convey.
The copyright length should be reduced from 70 years after the creators death to 20 years after the creation is publicly available
I do agree that it should be reduced to a maximum of the life of the copyright holder. The creator should be able to choose the length of copyright and should have a lot more freedom with how the copyright works. Example: so if John writes a book he can make the copyright 50 years or until death.
Nuclear armed countries are immune to total destruction by war.
It all depends on the country. If we are talking about a small (area) country such as the ones on the European Peninsula or Africa. Then they can be defeated but nuclear weapons may be sent before the other weapons hit. But If it is a large country then it would be a lot harder to defeat it.
You can't measure how good a programming language is.
A programming language could be measured by the efficiency of the language. Or the cross-platform nature of it. So a language can be good in some circumstances but not as good in others.