No; this is absolutely wrong. There's no such thing as "adopting rationalism"; it's in our nature to attend to evidence and logical coherence and everyone is approximately rational. The question is whether we do this consistently and with discipline, not whether to do it at all.

It's like saying that there's some sort of extra-food possibility in everyone's past, and some people choose to eat and others don't. We can eat well or badly, but we can't just opt in or out of eating.

If "adopting rationalism" is an intentional action, then occurs against the background of approximate rationality; if it doesn't, then it isn't an action.