Positive synonym for "skepticism"?

Hello to anyone who sees this!

I'm looking for a word similar to "skepticism", but more positive. (Here, I define skepticism as the belief that we can never have certain knowledge.) Sorry if this format is weird, trying to follow the rules of single word requests:

• Usage: "There was still much ___, but it had to be done."
  • Might be unclear, this noun describes a view/feeling, not a person.
• I've searched for synonyms for skepticism, doubt, dubiety, etc. Not on any specific websites, just looking the words up on Google and clicking any results that looked useful.
• I've got some pretty specific needs for this.
  • I'd prefer:
    • a short word, as in less characters and as many or less syllables as "skepticism"
    • a word that means something similar to being willing to question and give up beliefs
  • I need:
    • an English word specifically, even if it's a lesser-known one
    • a noun
• Words I've tried are all too negative, or they switch too easily.
  • "Skepticism" - it's a very interesting, but still too strong, view in philosophy.
  • "Doubt" - this is mostly used in a negative way, as in "but still, they doubted him".
  • "Uncertainty" - this sounds less like questioning your beliefs, more like general confusion.
  • "Hesitancy" - this is questioning, but it's seen more as a weakness than a strength.
  • "Incertitude" - less a question, more a feeling that you don't actually know something.
• I'm okay with closed compound words, but no hyphens.

Thank you in advance for any help, and if I need to change anything in the question, please let me know. This question is probably unnecessary, and I probably missed something when looking around.

Perhaps debate suits your purpose: it's shorter and has less syllables than skepticism while meaning the same in a less negative manner (debates can be and usually are healthy).

"There was still much debate, but it had to be done."

or perhaps

"It was the subject of much debate, but had to be done."

Macmillan:

debate NOUN

1 [COUNTABLE/UNCOUNTABLE] a discussion in which people or groups state different opinions about a subject

be the subject of much/some debate: Her books have been the subject of much debate.

What about simply

open? I would have to slightly change your sample sentence:

Much was still open, but it had to be done.

• Confirmation is still needed.

Or

• I'm reserving judgment for now.

How about "much questioning"?

(You used "willing to question" among the characteristics you seek)