AN OUTLINE OF THE NECESSARY

LAWS OF THOUGHT;

A TREATISE ON PURE AND

APPLIED LOGIC.

BY WILLIAM THOMSON, M. A.

FELLOW AND TUTOR OF QUEEN'S COLLEGE OXFORD.

Καλὴ μὲν οὖν καὶ θεία, εὖ ἴσθι, ἡ ὁρμὴ, ἣν ὁρμᾶς ἐπὶ τοὺς λόγους· ἕλκυσον δὲ σαυτὸν καὶ γύμνασαι μᾶλλον διὰ τῆς δοκούσης ἀχρήστου εἶναι καὶ καλουμένης ὑπὸ τῶν πολ λῶν ἀδολεσχίας, ἕως ἔτι νέος εἶ· εἰ δὲ μὴ, σὲ διαφεύξεται ἡ ἀλήθεια. PLATO.

ΤΟ

SIR WILLIAM HAMILTON, BART.

PROFESSOR OF LOGIC AND METAPHYSICS IN THE

UNIVERSITY OF EDINBURGH,

ETC. ETC.

THIS ESSAY

IS BY HIS PERMISSION INSCRIBED.

OME account of the exact pofition which this work pretends to occupy amidst a crowd of valuable treatises on the fame fubject, may not be an unfitting introduction to its pages. The fyftem of Pure Logic or Analytic that has been univerfally accepted for centuries past, is very defective as an inftrument for the analysis of natural reasoning. Arguments that commend themselves to any untaught mind as valid and practically important, have no place in a fyftem that profeffedly includes all reasoning whatever: and an attempt to reduce to its technical forms the first few pages of any scientific work, has generally ended in failure and disguft. The confequence has been that the more popular writers on Logic have begun to treat its strictly technical parts with a certain coyness