To me you either 1) have the many years of specialized education required to understand (for real) how vaccines works, or 2) trust the national and international institutions that vouches the work of estimeed scientists, or 3) do your research and perhaps watch your children die of fucking measles.
Trying to convince someone that chose no.3? Your only hope is to make them understand that they cannot understand, a very very hard task.
That is precisely the reason why you are not "free to add new features without having to battle over philosophies".