<p>I basically agree with @amoeba's reasoning. The rest of this post is just elaboration.</p>

<p>As a matter of expedience, I think it makes sense to down-vote <strong>old</strong> questions (posted more than 12 months ago) which are off-topic, low-quality, or too broad to be answerable. It takes five people to vote to close a question, but just one person to move a question from 0 score to -1 score. As a matter of policy, SE deletes questions with negative score and no answers (or no answers with positive score) on approximately a weekly basis. On a less-frequent basis, 0-score questions are deleted under certain conditions. It's not a very efficient use of resources to have 5 people involved in closing a <em>years-old</em> question that asks for code, or "which test do I run?".</p>

<p>There's a reason that I advocate down-voting <strong>old</strong> questions specifically. The closure queues are primarily oriented around giving recently-active users useful feedback on how to improve a question. <strong>Recent</strong> questions which might be off-topic or otherwise unsuitable should absolutely be placed in the queue so that active users can receive that feedback and improve their questions. <strong>We want to encourage new users.</strong></p>

<p>In all cases, duplicate questions should be closed as duplicates, so that our canonical content is ranked highly by search engines &amp; are otherwise more visible to users.</p>

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<p>My overall philosophy regarding down-voting is that it should be <strong>rare</strong> and <strong>carefully considered</strong>. This is because down-voting is pretty strong negative feedback. </p>

<ul>
<li><p>Down-voting that is not accompanied by a considered request for clarification or other context is inscrutable to the person who received the down-vote.</p></li>
<li><p>Because <a href="https://stats.meta.stackexchange.com/questions/5325/we-have-a-very-large-widening-gap-between-questions-and-answers-how-do-we-fix">we need more answers, and therefore more answer-writers</a>, I am particularly cautious about down-voting of new users. Today's new user could be tomorrow's high-value contributor.</p></li>
</ul>
