How do we know what we know?

[DLJ]

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Then on the quantum level, we know that the act of observing particles is enough to change them.
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I'm not sure that 'change' is the correct word. 'Decide' might be a better way of looking at it.

State vector reduction (collapse of the wave function) would be a bit like a choice between two paths. Once you've decided, you've collapsed the future function.

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This then begs the question
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It doesn't. It raises it.

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objectively true
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Ugh! Will no one rid me of this turbulent word?

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What can we confidently say is objectively true and true independent of the human experience?
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"And"? So what is the difference between a) objectively and b) independent of the human experience?

True (or false) is a label applied to a proposition for a given epistemology. It's relational, by definition.

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How much can we confidently say is true and how much are we assuming is true for the sake of our collective sanity?

Think of all the social constructs we accept as normal unthinkingly (because they've been grandfathered) or rationally (because we recognise the social value)... 'money' being an obvious example of both.

Nothing is real.
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Except Strawberry Fields.