Essays on the active powers of the human mind Book

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER II. OF HYPOTHESES. I. Proneness of Philosophers to build on Hypotheses.] Every branch of human knowledge has its proper principles, its proper foundation and method of reasoning ; and if we endeavour to build it upon any other foundation, it will never stand firm and stable. Thus the historian builds upon testimony, and rarely indulges conjecture. The antiquarian mixes conjecture with testimony ; and the former often makes the larger ingredient. The mathematician pays not the least regard either to testimony or conjecture, but deduces every thing, by demonstrative reasoning, from his definitions and axioms. Indeed, whatever is built upon conjecture is improperly called science ; for conjecture may beget opinion, but cannot produce knowledge. Natural philosophy must be built upon the phenomena of the material system, discovered by observation and experiment. When men first began to philosophize, that is, to carry their thoughts beyond the objects of sense, and to inquire into the causes of things, and the secret operations of nature, it was very natural for them to indulge conjecture ; nor was it to be expected that, in many ages, they should discover the proper and scientific way of proceeding in philosophical disquisitions. Accordingly, we find that the most ancient systems in every branch of philosophy were nothing but the conjectures of men famous for their wisdom, whose fame gave authority to their opinions. Thus, in early ages, wise men conjectured that this earth is a vast plain, surrounded on all hands by a boundless ocean ; that from this ocean the sun, moon, and stars emerge at their rising, and plunge into it again at their setting. With regard to the mind, men in their rudest state are apt to conjecture, that the principle of life in a man is his...