Complex sentence: In this second volume, Piper also developed a conception of human agency, based on a foundation of logical consistency as literal self-preservation, which explains how reason can be motivationally effective in the absence of desire, and why it so rarely is in practice.
Split into simpler sentences: In this second volume, Piper also developed a conception of human agency, based on a foundation of logical consistency as literal self-preservation. She argues that this overriding disposition explains how reason can be motivationally effective in the absence of desire, and why it so rarely is in practice.