بالقياس على

You place this phrase right before the thing you are comparing against. It usually starts a sentence or connects two clauses. You follow it with a noun or a noun phrase. For example, بالقياس على العام الماضي means "By analogy with last year." It sounds very smart and structured. Use it when you want to sound convincing in an argument.

Use it in professional meetings to predict future trends. It is great for academic writing or legal discussions. You can use it when debating with friends about movies or sports. It works well when you are explaining a complex idea. If you are justifying a decision, this phrase is your best friend. It shows you have a clear, logical basis for your thoughts.

Do not use this for simple, physical comparisons. If you just want to say someone looks like their brother, use مثل. Avoid it in very casual, slang-heavy conversations with teenagers. It might sound a bit too 'professor-like' at a loud party. Do not use it if the two things are not actually comparable. Logic fails if the foundation is weak, and so does this phrase.

This phrase has deep roots in Islamic jurisprudence, known as Qiyas. Scholars used it for centuries to derive new rulings from old ones. It is a cornerstone of classical Arabic logic and philosophy. Because of this, it carries a weight of authority and intellect. When you use it, you are tapping into a long history of reasoning. It makes you sound like a deep thinker.

You might hear people say قياساً على which is slightly shorter. Another variation is على غرار, though that means "in the style of." In very formal settings, you might see من باب القياس. Stick to بالقياس على for the most versatile and common usage. It is the gold standard for making a logical point clearly.