Isaac Watts, Logic: Or the Right Use of Reason in the Inquiry after Truth

Reprint, Kessinger Publishing, nd; Edinburgh, Charles Elliot: 1781 

Summary: A basic undergraduate level introduction to traditional or formal logic by the pastor and hymn writer Isaac Watts (1674-1748). The book was used in colleges up until the mid to late 1800s. 

Logic is the movement of ideas from apprehension to the relationship of ideas as judgment to deductive inferences that are repeatable and testable by others. Formal deductive logic allows us to learn or confirm new truth from already established truths.

The formal system was developed by Aristotle and was the norm in the West until mid-1800s. The system remains a powerful tool for analysis. Watts offers a helpful introduction to logic by showing us how to move from simple apprehension to definitions or terms, from terms to judgments written as the four propositions (All S is P; Some S is P; No S is P; Some S is not P) to deductive inferences. 

I will at a later date attempt a more careful explanation of deductive logic, but for the purposes of this review I will highlight some of the theological/philosophical issues within Watts’ Logic.

The Thomistic (Catholic) and Augustinian (Reformed) branches of Christian theology came to different understandings on the relationship of nature and grace deep within their theological systems—very often at the level of unarticulated presuppositions (cf. articles on Catholic Catechism). Thomists tend to assume no intrinsic knowledge of God and the perfection of nature by grace. This requires that all knowledge come to humanity through senses, as taught by Aristotle, and a more positive outlook on the moral and intellectual faculties. Augustinian thought assumes some intrinsic knowledge, as taught by Plato, and a more negative view of the noetic capacities.  

Regardless of judgments made about human capacities and epistemology, Aristotelian or formal logic functions well. The issue is that the prior theological conclusions are often imbedded in the description not of logic but how information is gleaned and human capacities. 

Watts is clearly Reformed in his Logic:

. . . . judgment has something of the will in it, and does not merely consist in perception; since we sometimes judge, (though unhappily) without perceiving, and sometimes we perceive without immediate judging (136).

The move of attaching the faculty of the will to judgment allows people to be unconsciously disingenuous as described by the Apostle Paul in Romans 1:18-32. Watts then adds to this:

But among all the causes of false judgements which are within ourselves, I ought by no means to leave out that universal and original spring of error, which we are informed of by the word of God; and that is, the sin and defection of our first parents; whereby all our best and natural powers both of mind and body are impaired, and rendered very much inferior to what they were in a state of innocence. Our understanding is darkened, our memory contracted, our corrupt humors and passions are grown predominate, our reason enfeebled, and various disorders attend our constitution and animal nature, whereby the mind is strangely imposed upon in its judgment of things (198). 

And he reiterates the problem on the issue of the fear of man: 

Besides all this, there is a fashion in opinions, there is a fashion in writing and in printing, in style and language. . . This business of the fashion has the most powerful influence on our judgments; for it employs those two strong engines of fear and shame to operate upon our understanding with unhappy success. We are ashamed to believe or profess an unfashionable opinion in philosophy, and a cowardly soul dares not so much as indulge a thought contrary to the established or fashionable faith, nor act in opposition to custom, though it be according to the dictates of reason (203-204). 

He drops a form of the ontological argument as aside on the fact that “the mere possibility of a thing we cannot infer its actual existence; nor from the non-existence of it can we infer its impossibility” (234).

Note, The idea of God seems to claim an exemption from this general rule; for if he be possible, he certainly exists, because the idea includes eternity; and he cannot begin to be; If he exists not, he is impossible, for the very same reason. 

Benefits/Detriments: Watts is in many ways a good, clear, and wholesome teacher of logic, reasoning, and Reformed thought. 

I suspected logic seemed almost intuitive to him after appropriating the definitions; therefore, he is impatient and dismissive of providing mnemonic devices, schemas to assist analysis, or example problems. The book frames logic well, but it doesn’t provide the necessary case studies to fill in the details. It’s rather like an algebra book with very, very few example problems and no answer key. 

Recommended as an explanation of logic and as a corrective for more Thomistic books like Basic Logic by Raymond J. McCall and Martin Cothran’s homeschooling curriculum through Memoria Press. Could be assigned as a textbook by someone having mastered formal logic. Late high school or mid-college reading level. Avoid the Kessinger reprint because of orthography issues.