On the Fourfold Root of the Principle of Sufficient Reason, and On the Will in Nature: Two Essays (revised edition)

The first essay offers an analytic account of the principle that every fact requires a sufficient reason, distinguishing four distinct forms of that principle corresponding to different domains of explanation — grounding causation, the conditions of perception and spatial/mathematical relations, logical inference, and practical motivation — and showing how these forms delimit what can be known. The second essay treats natural phenomena as manifestations of a blind, striving will immanent in organisms and physical processes, arguing that teleology appears only as an expression of underlying will and exploring implications for biology, psychology, and the philosophy of nature.