DEMONSTRATIVE REASONING AND DEDUCTIVE EVIDENCE Demonstration applicable to mere Concepts, not to Real Things Why Mathematical reasoning is demonstrative Mathematical evidence not a mere perception of identity Want of Universality in the Sumption fatal to strict Reasoning LOGIC. CHAPTER I. PSYCHOLOGICAL INTRODUCTION. Intuitions distinguished from Concepts. — Mental Characteristics of Brutes. Relations of Thought to Language. THE HE beginning of all knowledge is in single acts of the Perceptive or Acquisitive faculty, each of which relates immediately to an individual object or event. Such acts are called Intuitions or Presentations; the former is the more generally received appellation. Each Intuition gives us a knowledge of its object so far only as this object is. perceived now and here, and also as it is one, or undivided, though not necessarily indivisible. To recognize, or know over again, the object as similar to another thing perceived on a former occasion or in a different place, or to analyze it into its parts or attributes, or to refer it to a class of things previously known, and thereby to give it a common name, requires the aid of a different and higher power of the mind. In receiving Intuitions, the mind exerts no conscious activity whatever; it is passively receptive of any impressions that may be made upon it, and does not in any way consciously react upon or modify those impressions. It is like a mirror reflecting the objects that are held up before it, perhaps giving distorted or unfaithful images of them on account of the imperfections of its own surface, but hav ing no power to change or in any way affect them by its own will. The impression made upon my mind by the portrait of a friend which I am now looking at, as it hangs before me, or by the sounds to which I am listening as they are struck upon a violin; the image now present to my memory of the relative whom I have recently lost; the picture of a waterfall in a wood which my imagination at this instant forms; the consciousness which I have of the present state of my own mind; all these are Intuitions, as each one of them relates to a single object, and each is immediate, that is, it does not come through the intervention of any other state of mind. But what is denoted by the word man, sound, or waterfall, is not an Intuition, for it does not refer to one object only, but to many. Man, for instance, includes under it John, Thomas, William, and many others; and it does not convey a complete image of any one of these persons, but only a partial representation equally applicable to any of them. John, when considered simply as man, is not regarded as he really is, that is, as possessing all his individual attributes and peculiarities, but only as having those attributes which he possesses in common with all other men; he is not viewed immediately, but only through the medium of what is called a Concept, or a Thought of what is common to many. These words, therefore, man, sound, waterfall, and all other common names, do not denote Intuitions, but Thoughts. The Perceptive or Acquisitive faculty, through which we receive Intuitions, as it is a merely passive power, or a capacity of being affected in a certain way, constitutes what may be called the receptivity of the mind. The Thinking or Elaborative faculty, -i. e. the Understanding, as it has no Intuitions of its own, but voluntarily reacts upon and modifies those received from the Perceptive faculty, comparing them with each other, and thereby combining |