Word for someone who focuses on the smaller details of a bigger problem

I'm not sure if the title correctly describes what I'm looking for.

For example, there is a debate about the existence of something, and one party focuses on the small unexplained details in their opponents' argument and do not address the gaping holes in theirs.

For a single word, I suggest myopic:

Myopic is an adjective meaning shortsighted in every sense. Whether you need glasses or a new attitude, if you can't see the forest for the trees, you're myopic.
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However, for the example you provided, I would describe the person as a lawyer.

It's not a single word, but the expression can't see the wood for the trees refers to exactly this situation (reference).

When the problem consists of something no-one wants to acknowledge or talk about, it is very often referred to as 'the elephant in the room'.

In passing, it's worth noting that you generally can't get many elephants into a room, but there's usually quite a lot of room inside an elephant.