From a legal standpoint: Copying even a substantial part of a book for purely academic, educational, and/or personal use *could *easily fall under the “fair use” doctrine (meaning it would not be a violation of copyright). In the U.S., the limited monopoly that copyright grants is for purely economic purposes (to “promote the sciences and the useful arts”). We do not consider it a “moral right,” and so otherwise productive uses that don’t cause market harm are not considered to be in the scope of the monopoly.
From a moral standpoint: “Stealing” is taking something that, legally, belongs to another, so it seems the legal distinction makes a moral difference. “Intellectual property” is not really the same as personal property and real estate. By nature, its more expansive because it attaches to the intangible material and not the medium. It seems that we should not have a monopoly or “ownership” over ALL of our intellectual inventions (e.g., “ideas” are not copyrightable), but just enough that gives us incentive to create and invent in the first place. Because this is the guiding principle for the legal scope, should this make the difference for the moral scope as well?