I don’t know what kind of fallacy this is, but it drives me absolutely insane. It’s that kind of ‘patchwork’ reasoning, where somebody states a premise like,

“It’s bad for small children to be in daycare because the undivided attention of their mother is better for their developing brains than the rowdy company of other children.”

Then, you start looking at that claim in other contexts like extended families, large families, community care of children. Then they switch to:

“It’s bad for small children to be in daycare because you don’t know all the adults personally & paedophiles are drawn to working with small children. Communities and extended families are fine and large families are excellent.”

OK, but this is an entirely different claim. We were looking at whether children’s brains develop better with one-on-one adult attention or with a significant amount of time spent playing with other children. You’re now in the realm of being able to vet all adults personality. Do you want to abandon the first argument and switch to looking at whether children are more likely to be abused in a daycare or by a family member? Because we can do all of those things and should to consider pros and cons of daycare but they need to be separated out.

It’s like some people’s brains work on building blocks where they’ll separate out distinct issues like child development, safety, financial considerations etc. and form an opinion on what is better on each of these and then stack them up to make a final decision. Meanwhile other people’s brains work like a patchwork. They know what conclusion they want to get to and then they’ll take bits and pieces of various elements and just sew them all together to make the case they want to make.