It’s an alternative source of evidence towards philosophical theses. - It’s not always meant to undermine traditional (armchair / mathematical) philosophy.
Philosphers use “our intuitions” as evidence for a compatibilist view
Among all our externally determined actions, they need to identify a subset of them as “free” - meaning things for which people can be credited/praised/blamed for.
Our concept of “freedom” is compatible with our concept of “externally caused”
To demonstrate this, they use a thought experiment, but empirically we find that the result of that experiment by varying trivial details - calls into doubt whether the thought experiment was only convincing to a biased group of people.
We tend to believe people can be held accountable when the stakes are higher (the thought experiment example action is trivial => people conclude determinism, the action is something heinous => people conclude compatibilism)