Lectures on mental disease.
- Sankey, W. H. O. (William Henry Octavius), 1813-1889.
- Date:
- 1884
Licence: Public Domain Mark
Credit: Lectures on mental disease. Source: Wellcome Collection.
Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.
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![lines, than in that very act wo make present the imiiosBibility of their meeting, and only as the imago becomes obscure does the idea of meeting become possible. That this is a fact therefore gained from experience is clear. (Lewes, loc, cit.) But in fact the attribute of not meeting is the distinguishing property of parallel lines; they are named from this attribute, and so soon as they lose it, they would no longer answer to the definition, on this depends the necessity and the certainty of the cognition. Again to take another example, if all necessary truths are a priori judgments, then that three and two make five must be an a priori judgment, because by no effort, or freak of thought can we imagine three and two to make seven. If they are d ]}riori they cannot be a posteriori, or in other words the outcome of experience. Certainly by no freak of thought, says Mr. Lewes, can Dr. Whewell believe that two and three are seven. This is quite true, and that it makes five, is to him a necessary truth, but that is evidently a matter of pure experience and slowly acquired knowledge too. One might easily believe that 472 and 274 made 646 or that 365 and 365 made 720, Yet when one had made an accurate calculation, he would find that the first two numbers made 746 and not 646, and the latter 730 and not 720 ; and having once obtained the correct result, the correct figures would be necessary truths, which by no power could we believe to be incorrect, but the result was a labori- ously acquired knowledge. Not only therefore are these, and many similar judgments which might be quoted, not a priori, though they have all the character of necessity. This character of necessity is therefore not due to what is attributed to some independent and innate faculty of the mind. To what then can we trace it ? It will be seen that it depends upon the precision of the terms used in expressing the judgment; these necessary truths consist of abstractions, and the terms used to note them are free from ambiguity. The truth depends, as Lewes says, on the exactness of the terms. All A is A is true and necessary, but vary the terms as some A is some B, and there is no longer any necessity. The more ab- stract the term used the less does it include; therefore the higher the abstraction the greater generally is there the quahty of neces- £2](https://iiif.wellcomecollection.org/image/b2120844x_0075.jp2/full/800%2C/0/default.jpg)
