I tried to look for where the halakhic decisors write that there is an obligation to clarify, but I did not find it. Can you point me to sources?

For some reason I can’t paste links here.

https://daf-yomi.com/DYItemDetails.aspx?itemId=9699

I just found a WikiYeshiva entry on “a doubt that can be clarified”
https://www.yeshiva.org.il/wiki/index.php/%D7%A1%D7%A4%D7%A7_%D7%A9%D7%90%D7%A4%D7%A9%D7%A8_%D7%9C%D7%91%D7%A8%D7%A8%D7%95

But it seems that both this link and the link you brought are talking about factual doubt, not doubt in Jewish law. The question is whether doubt in Jewish law can be treated like factual doubt.

No. Because with doubt in the law there is no way to clarify it.

Sorry, I shouldn’t have used the term “doubt in the law.” My question is: if I am unsure about the Jewish law and it can be clarified by consulting a rabbi or looking in books, is that considered like factual doubt for the purpose of a doubt that can be clarified?

So in other words, the question is whether one has to study rabbinic laws. Obviously yes. By simple logic this is even clearer than the obligation to clarify the facts.

The link says this:

A doubt that can easily be checked and clarified is treated stringently in several cases (mentioned in tractate Pesachim 4a).

For example, if someone rents a house from his fellow on the fourteenth of Nisan, even though there is a presumption that the homeowner checked for leavened food, if the homeowner is in town one must ask him whether he checked (Tosafot on Pesachim 4a, s.v. “lav”).

My question is whether, when it comes to Jewish law that can indeed be clarified but not easily—for example, on the Sabbath, a person wants to do something and does not know the Jewish law, and clarifying it would require him to invest a few hours—can he rely on the laws of doubt as one does in a factual doubt that is difficult to clarify, or is there a distinction here between the two?

Many halakhic decisors wrote that if it is difficult to clarify, then one is not obligated to do so (because that is not called “it can be clarified”). The line of what counts as difficult is not defined. Common sense. For example, one is not required to put an apple through an X-ray in order to know whether it has worms in it (an example brought in Minchat Shlomo). But regarding a halakhic doubt, in my opinion the line is much higher, if it exists at all. The Jewish law has to be clarified as part of knowing the Jewish law in general. There is no obligation to know the facts. That is only a necessity because I happened to end up in this situation. But there is an obligation to know the Jewish law.

You wrote above, “There is an obligation to know the Jewish law.”

I can understand that the obligation to know God’s will and Torah-level laws comes from the obligation to study Torah. But does the obligation to study Torah also include the rabbinic laws of the Torah? And if not, what is the source for the obligation to study rabbinic laws?

I don’t understand. How will you fulfill them if you don’t know what to fulfill?

I assume that if someone does not know certain rabbinic laws, he will not observe them out of ignorance. I am sure there are quite a few rabbinic laws that people do not observe because they are ignorant of them. But my question is more focused on a situation where there is a specific act in front of me. For example, on the Sabbath I want to move something, and I am unsure whether it is muktzeh or not. I know this is a rabbinic law. Is it permissible to be lenient and move the item because I am in doubt whether it is muktzeh or not, since in a rabbinic-level doubt one may be lenient? Or is there an obligation on me to clarify the Jewish law regarding this object—whether it is muktzeh or not? And if there is such an obligation, where is it learned from?

There is certainly an obligation, by simple logic. Rabbinic laws were instituted so that we would observe them. According to your approach, there would be no need to observe anything. Just don’t study and don’t observe.