Are downvotes via reasoning from analogy really justified?
I don't think so, that it just shows laziness, if not ignorance.
e.g. this question seems to be being downvoted on the grounds that it is like asking if "guns kills people"
We can't really know why people downvote unless they communicate their reasons in a comment. In a broader sense, we don't even know who votes; we just have an aggregate score. Only those with the privilege can see a breakdown by vote type. It might be that some people vote randomly and other people vote based on careful reasoning. We can't really tell the difference because we can't directly examine thought process behind each vote.
However, we have seen across many different topics that voting on questions generally does match the guidance we provide in the tooltip for downvoting:
This question does not show any research effort; it is unclear or not useful
On a site for philosophy, I'd expect questions to grapple with the thinkers that have gone before us. If a question doesn't reference a noted philosopher or school of philosophy, I'd tend to put in the category of "does not show any research effort".
Although this question is a duplicate of this one, this one and this one. It clearly has been and continues to be an issue for some people. The most recent question on Meta is also about downvotes. Obviously we cannot do anything about the SE system itself, but I do think that there should be more in the FAQ, or encouragement here on Meta for people to leave polite and constructive comments explaining downvotes.
If the intention of voting is to raise the best answers and lower the worst ones, then given the somewhat 'fickle' nature of humanity (especially it seems when they are granted the anonymity of the internet), I'm not convinced how useful it is being able to just register "I don't like that" with one click. It rather plays into the less rational side of community democracy which is exactly the opposite of good philosophy.
If we genuinely want the best questions and answers raised by voting (best in philosophical terms) then there needs to be some rational analysis of those competing questions/answers, otherwise we just have the 'most popular' raised to the top, which is not quite the same thing.