Yeah, I think a good question to distinguish the different philosophies here is: if we had a perfect lie detector, would you support defendants being compelled to use it, with adverse assumptions for refusing?

Only if we could restrict the questions to the facts of the case, but my phone has a lot of unrelated personal stuff on it and so does my brain.

So like, if you wrote a journal detailing a bunch of crimes and/or criminal motives, you don't think that journal should be admissable as evidence in a criminal proceeding? Nor do you think that a warrant should be capable of granting access to that journal for the purposes of a criminal investigation?

Within the narrow context that a journal is a mental device rather than "literally any document", yeah, I would prefer that be inadmissible.

They can take the journal. They can't compel me to provide a key to unencrypt the contents.

That part that's literally (and legally, AFAIK) part of your mind is the code you use to unlock your phone. You can't be compelled to hand that over. I believe the same logic would apply to gorgoiler's scenario if you had a keypad lock on the door (the cops might be allowed to physically break it, but they couldn't compel you to share the code). I'm no lawyer/expert, though.