Essentially, not without permission from the copyright holder (which might be, and might not be, the blog owner) — although you can generally use *snippets* of the text for purposes of discussion (but not the whole text, or most of it).
You could look up the domain name at a domain registrar to find out who the owner is.
— I am not a lawyer, etc. 🙂
You could try commenting on the post you want to use – that might get the attention of the owner.