Friendly Atheism

[John 6IX Breezy]

No, I would not say it is rational to believe vaccines work because scientists believe they work.  I would say that it is rational to believe that vaccines work because vaccines work.  But you have the proposition exactly backwards.  Would you believe someone is rational because they believe vaccines DON'T work?

Irrationality (as far as regards the topic at hand) seems to mean either believing a proposition to be true when there is no good reason for supposing it is, or believing a proposition to be false in the face of overwhelming evidence that it is true. 

Let's take the virgin birth of Jesus as an example from religion.  Parthenogenesis never occurs naturally in mammals - it isn't physically possible.  However, it can be induced in mammals with some very complex procedures, such as gene splicing and fiddling about with stem cells.  It is therefore non-rational to believe that Jesus was the result of a virgin birth (a much more likely explanation is that Mary told a fib or two).  It doesn't matter how may people believe that it happened, or how sincerely this belief is.  Since it flies in the face of the observed facts, it is not a rational belief.

Boru

I think most people believe vaccines work, or don't work, on authority. The average person has neither the time, interest, or ability to read published research on vaccines, and simply trust that scientists have it figuired out. I'm scientifically trained, and I still struggle to understand research published in other fields. I think most people build and defend their positions using news articles that interpret and report the original research, giving it a narrative. Vaccine debates tend to also be partisan precisely because news outlets are partisan. But from what I've seen, anti-vaxers have their reasons, such as a distrust of authority (particularly governments, or fraud in the scientific community), that makes their position rational.

I think your virgin birth example is interesting. You seem to imply that it's possible, just not natural, it requires intervention. Isn't that what Christians say? The story isn't that the virgin birth happened naturally, but that God intervened. The virgin birth is rational if God exists; it isn't inherently irrational.