The Remains of John Corbet, Section 1
§ 1. Of Certainty in general.
I Begin the enquiry, by taking notice of the common diſtinction of objective and ſubjective Certainty. Objective Certainty, or Certainty in the object, is the immutable verity of the thing it ſelf. For that a thing is what it is, is unchangeably true. Subjective Certainty is the firmneſs of aſſent to a thing apprehended as it is. It is this later which I enquire into, and it preſuppoſeth the former.
It muſt be ſuppoſed that our faculties are true; that is, that in their ſound ſtate, and ſet in due circumſtances, they are adapted to diſcern things as they are indeed. Otherwiſe the queſtion of the nature of Certainty is out of dores, there being no ſuch thing in the world.
Certainty of Aſſent includes three things: 1. That it be firm, without ſtaggering. 2. That it be true, and not erroneous. 3. That it reſt upon firm and ſure grounds. The firſt is evidently neceſſary, becauſe it is the very notation of the word Certainty; the notion we mean thereby, is not to doubt or ſtagger in our apprehenſion of a thing. The ſecond is as evidently neceſſary; for Certainty is an affection of knowledg; but an erroneous apprehenſion is not knowledg, but ignorance; a confident miſtake cannot be certainty. The third alſo is clear; for if the grounds be either falſe or weak, the knowledg built thereon cannot be ſure, Tho the aſſent be true in reſpect of the object, yet it is not certain in this caſe, becauſe not judicious nor ſolid; yea, tho the apprehenſion be according to the thing, yet as far as it reſts upon a falſe or weak ground, it is not knowledg properly ſo called, but a caſual confidence or preſumption; and when the inſufficiency of the grounds ſhall appear, the apprehenſion fails, and vaniſheth away.
Meer probability is not Certainty ſtrictly ſo called; it is indeed an affection or mode both of knowledg, and of error, which is a kind of ignorance: for that which is only probable, may either be, or not be what it is apprehended to be; and ſo the apprehenſion thereof may be either true or falſe, either knowledg or error. Yet the apprehending of a probable thing only as probable, is always a right apprehenſion; for whether the thing be or not be, it is certainly true that it is probable.
The reaſon of probability lies in a ſufficient evidence that a thing not only may be, but is ſo indeed, rather than not ſo, as it is apprehended to be. The reaſon of Certainty lies in a ſufficient evidence, that a thing muſt needs be as it is apprehended: For if there be not ſuch evidence, then if we indeed conſider the matter, we preſently apprehend, that in regard the thing may be otherwiſe, it is ſo for ought we know, and that our apprehenſion or opinion about the thing is falſe for ought we know. That there is neceſſarily ſome kind of needs muſt be, in the object of a certain, that is, a firm aſſent, ſeems to me to have ſelf-evidence, and to need no proof.
An Object or Matter of Certainty being that which is in ſome reſpect neceſſary, or that cannot but be ſo, is to be underſtood not only of abſolutely, but hypothetically neceſſary; and of a thing neceſſary not only in regard of eſſence or abſtracted nature, but by neceſſity of exiſtence in this ſenſe, viz. Whatſoever is, whileſt it is, neceſſarily is; and that which hath been, neceſſarily hath been; and that which ſhall be, neceſſarily ſhall be, becauſe it is a contradiction to be and not to be.
The ſurer the grounds are, and the greater the evidence is in the kind of probability, the nearer it approacheth to certainty; and the weaker the grounds are, and the leſſer the evidence is, the farther it is from it: Therefore very high degrees of probability commonly borrow the name of certainties, and the minds of men do ordinarily reſt therein. The buſineſs of men as to this world generally proceeds upon no better aſſurance, than high degrees of probability.
Learned men ſpeak of a conjectural certainty or opinion that excludes doubting. I contend not about the name, provided the ambiguity be taken away: If by doubting they mean a fluctuation, or not fixing of aſſent; and by certainty, a fixed aſſent, I grant that in this ſence there is a conjectural certainty, when the mind ſaith undoubtedly the thing is ſo, and reaſon will not ſuffer me to judg otherwiſe: But I judg, that certainty properly ſo called, is an aſſent excluding not only fluctuation, or non fixation or ſuſpence, but alſo an apprehenſion that the thing may be otherwiſe; and it reſts upon no evidence inferior to that which is called demonſtrative; an aſſent whereby the mind ſaith not only, I believe that I am not herein deceived; but alſo I believe that I cannot herein be deceived: For if I believe only that I am not deceived, but not that I cannot be d…ceived herein, I am not ſure that I am not deceived herein; for it may be otherwiſe than I apprehend; and for ought I aſſuredly know, it is ſo; and here is no certainty properly ſo called. Note, that when I ſay I can be deceived, I do not mean in every thing, but only quoad hoc: For ſpeaking indefinitely, we may truly ſay ſuch a perſon may or can bedeceived; yet it may be true that in this or that determinate caſe, he cannot be deceived. The Apoſtles in their Apoſtolick Embaſſy could not be deceived, yet in common matters they might be deceived like other men.