One common characteristic of science denialists/cranks/conspiracy theorists like antivaxxers and #COVID19 deniers is black-and-white, all-or-nothing thinking when it comes to medical tests or interventions. I'll tell you what I mean, using antivaxxers as a first example. 1/

I've seen it time and time again. Antivaxxers have an attitude that if a vaccine is not 100% safe and 100% effective, it's worthless, rather like that Mike Myers sketch. 2/

So, basically, to antivaxxers, if a vaccine isn't perfectly effective and safe, it's crap, not worth using and to be despised. The concept of balancing large benefits vs. tiny risks never even occurs to them. 3/

As an aside, antivaxxers give the game away when they vastly exaggerate the risks of vaccines and downplay their benefits. It's as though they know that there is such a thing as a risk-benefit analysis, but they want to distort the analysis to fit their preconceived beliefs. 4/

You'll see the same thing with #COVID19 cranks, such as antimaskers. (There's one on my blog right now.) To them, if masks aren't 100% effective in protecting you from coronavirus, then they are worthless. 5/

Of note, they don't care much if masks keep you from spreading your virus-laden respiratory droplets to other people. They only care if masks protect THEM. They do, but not anywhere near perfectly, which to antivaxxers is basically the same as not protecting at all. 6/

It's little wonder how fast antivaxxers became #COVID19 conspiracy theorists and vice versa, sadly. 7/7