Can the phrase 'certain level' imply 'not so much in quantity'?

Question

I'm a high school student learning English in South Korea. In my exams, there was a question asking to choose the phrase that best fitted the following blank.

This is evident in the changing approaches towards expert knowledge, from full trust in the skills of the expert to a reserved trust, which ____________.
(See the full passage below)

There were two choices I was having a hard time choosing between. One of them was "makes people need a certain level of trust with experts" and the other was "puts too much a burden of judgment on the individuals".

I chose "makes people need a certain level of trust with experts", believing that the word 'certain' implied 'not so much in quantity and the phrase itself could be used to emphasize the change from full to reserved trust. Also, I thought it was illogical to say "too much", given there were no further mentions about the individuals.

But the answer was not the one I chose and my teacher told me that the word 'certain' should just be interpreted as 'some specific quantity. I am not really satisfied with his reasoning and was wondering if anyone can tell me how my understanding of the phrase is not appropriate.

Full passage:

As scientific knowledge has substantially expanded, our approach to knowledge may have changed: the earlier naive beliefs in undeniable truths have given way to the contextualization of knowledge, dramatically expressed as the end of grand narratives. This is evident in the changing approaches towards expert knowledge, from full trust in the skills of the expert to a reserved trust, which ___________. A major shift from ‘science’ to ‘research’ is identified in the production of scientific knowledge. Scientific knowledge allows us to develop new technologies, solve practical problems, and make informed decisions — both individually and collectively. According to this shift, knowledge becomes less final and more open to change. Science was associated with ‘certainty, coldness, aloofness, objectivity, distance, and necessity’, but research was, in contrast, ‘uncertain; open-ended; immersed in many lowly problems of money, instruments, and know-how’.

Answer 1

In the context of your quote, "certain" carries the sense of an indeterminate amount.

certain adjective 2 attributive Specific but not explicitly named or stated. 2.1 Used when mentioning the name of someone not known to the reader or hearer. ‘a certain General Percy captured the town’ -Lexico

If we go strictly by the definitions above, your teacher is correct. However, in your context, it is the "not known" sense that dominates, not the "specific quantity" sense.

Since it is trust that is being discussed (or perhaps quantified), you might ask what the units are, or what the quantum might be. Can you halve or double it in any quantifiable sense? If you can't, there can be no "specific quantity" contemplated.

In this sense, you are correct in saying that "certain" is qualitative rather than quantitative in this context.

Looking more broadly, though, the question is asking for a phrase that is communicates a 'reduction in trust'. It isn't that some level of trust is needed, it is that trust is eroded.

Now, if you are able to trust some experts, some portion of an expert's skills, or perhaps even just an incomplete sense of confidence in a specific expert's specific skill, you can argue that the individual now has the burden of judgment in relation to which expert or which skill etc to trust. This makes the second option a viable answer when the only alternative is the first option.

Nevertheless, I'd consider even the second option to be in some kind of qualitative consistency with the first part of your quoted sentence, rather than being a restatement or necessary implication.