474 LOGIC: oE, THE RIGHT USE OP REASON. the Author of nature doth not vary but upon very important oc- casions. 2. Where antecedents, concomitants, and consequents, causes, and effects, signs and things signified, subjects and ad- juncts, are necessarily connected with each other, we may infer the causes from the effects, and effects from causes, the antece- dents from the consequents, as well as consequents from antece- dents, &c. and thereby be prettycertain of many things both past, present, and to come. It is by this principle that astronomers can tell what day and hour the sun and moon were eclipsed five hundred years ago, and predict all future eclipses as long as the world shall stand. They can tell precisely at what minute the snn irises or sets this day at Pequin in China, or what altitudes the dog-star had at mid -night or mid 'noon in Rome, on the day when Julius Caesar was slain. Gardeners upon the same prin- ciple can foretel the months when every plant will be in bloom, and the ploughman knows the weeks of harvest : we are sure, if there be a chicken, there was an egg : if there be a rainbow, we are certain it rains not far off: if we behold a tree growing on the earth, we know it has naturally a root under ground. 3. Where there is a necessary connection between causes and effects, antecedents and consequents, signs and things sig- nified, we know also that like causes will have like effects, and proportionable causes will have proportionable effects, contrary causes will have contrary effects and observing men may form many judgments by the rules of similitude and proportion, where the causes, effects, &c. are not entirely the same. 4. Where there is but a probable and uncertain connection between antecedents, concomitants, and consequents, we can give but a conjecture, or a probable determination. If the clouds gather, or the weather -glass sinks, we suppose it will rain: if a man spit blood frequently with coughing, we suppose his lungs are hurt : if very dangerous symptoms appear, we expect his death. 5. Where causes operate freely, with a liberty of indifference to this or the contrary, there we cannot certainly know what the effects will be : for it seems to be contingent, and the certain knowledge of it belongs only to God. This is the case in the greatest part of human actions. 6. Yet wise men, by a just observation of human nature, will give very probable conjectures in this matter, also concern- ing things past, or things future, because human nature in all ages and nations has such a conformity to itself. By a knowledge of the tempers of men, and their present circumstances, we may be able to give a happy guess what their conduct will be, and what will be the event by an observation of the like cases in
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