PrepTest 102, Section 2, Question 20
Physicist: Determinism is the view that every event(77 more words not shown)
The physicist's reasoning is most(10 more words not shown)
- AThat it is(32 more words not shown)
- BThat the complete(29 more words not shown)
- CThat it is(31 more words not shown)
- DThat it is(28 more words not shown)
- EThat the position(30 more words not shown)
Reading the argument
Not knowing exactly how the universe works doesn't mean the universe lacks an exact way of working.
The physicist defines determinism as each event having an earlier cause sufficient to bring it about. Given the previous state, the next events couldn't have turned out differently. That's a claim about how events are fixed by what comes before them.
The evidence against it concerns what can be known: we cannot measure a particle's position and velocity accurately together, so we cannot know the complete state at a given moment. Even accepting that limitation, why would it establish that events aren't determined? An unknown state could still exist and produce the next event in a fixed way.
Saying gravity isn't real because a fish can't explain it would make the same kind of mistake. A limit on a creature's knowledge doesn't by itself decide what exists outside that knowledge.
What we’re looking for
For the flaw question, I'd look for the jump from what can be known to what is true of reality. We don't need to resolve physics or prove determinism. We need to see why the measurement limit hasn't disproved it.
Working the answers
- A
Knowing one property of all particles would still fall short of knowing their complete states, which would require the missing information too. The argument doesn't need to claim that neither property can be known. More importantly, separating what can be measured doesn't address the jump from incomplete knowledge to determinism being false.
- B
This describes moving from ignorance of the whole universe to ignorance of its individual particles. The physicist proceeds in the other direction: a limitation on measuring individual particles is offered as a reason we can't know the complete universe. The decisive unsupported step comes after that, when the limit on knowledge is used to reject determinism.
- C
Measuring position or velocity separately is compatible with being unable to measure both accurately at one time. That possibility wouldn't give us the simultaneous complete information the physicist discusses. We can grant the claimed lack of complete knowledge and still make our objection: it doesn't settle how reality itself behaves.
- DCorrect
A complete state of the universe could exist even if nobody could know it completely. The physicist treats an obstacle to knowing that state as an obstacle to reality being determined by it. D separates those two ideas. It doesn't prove that the existing state determines every later event; it shows why the given inability to know it doesn't establish the contrary.
- E
The premise already says the measurement limitation applies to any given subatomic particle, so applying it across the particles doesn't identify the central jump. Even if complete measurement were impossible for all of them, the question would remain whether that ignorance tells us determinism is false. E stays within measurement scope and leaves that issue untouched.
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