I haven’t read it yet, but this is a great idea for a book: Arguments for Liberty, edited by Aaron Ross Powell and Grant Babcock. Published by Cato in 2016, the volume collects nine essays by nine scholars, each arguing for liberty from a different philosophical perspective.
I expect that this volume is meant to be an internal-to-libertarianism instructional enterprise, targeting those already sympathetic to a free society but looking for professional presentations of the many different arguments — sometimes conflicting and sometimes compatible — that libertarians use to justify their approach.
The chapters are:
1. UTILITARIANISM by Christopher Freiman
2. NATURAL RIGHTS by Eric Mack
3. KANTIANISM by Jason Kuznicki
4. CONTRACTARIANISM by Jan Narveson
5. RAWLSIANISM by Kevin Vallier
6. VIRTUE ETHICS by Mark LeBar
7. OBJECTIVISM by Neera K. Badhwar
8. ETHICAL INTUITIONISM by Michael Huemer
9. MORAL PLURALISM by Jason Brennan
I know all of the authors to be serious thinkers, so I look forward to spending time with the collection.