What the argument does is imply or entail a conclusion. It doesn't infer it. In addition to arguments implying things, sometimes we talk about people implying things. In this usage, implying is an activity, but it's a different activity than inferring. And inferring is something people do.
People infer by looking at the evidence and deciding what hypothesis that evidence best supports.
When you imagine some possibility, you are not committing yourself to the claim that that possibility actually obtains or is likely to obtain. It's capable of being true or false. It's expressed in language by a complete sentence. A concept is usually expressed in language by a noun phrase, not by a sentence. The Charles River and my idea of the Charles River are two very different things.