Is it legal to download textbooks from academia.edu? There is a website called academia.edu. It seems like they have papers on various topics - but my question is about their textbooks. It is possible to download certain college textbooks for free through their site. This is a link to a calculus textbook you can download through the site.  

My question is: Is it legal to download textbooks from academia.edu (in the United States)?
Someone who downloaded a textbook from there could make the argument that they had good-faith belief that the content on the website is available for public use, and was not aware of any legislation barring them from such download.

Thus, even if somewhere in the world it is illegal (which I doubt), the person downloading the book is extremely unlikely to get prosecuted or sued, and were they to be prosecuted - extremely unlikely of being convicted.

This, as opposed to textbooks you somehow got (without being able to make any assumptions about the source of the file.