is simply the existential compatibility of a thing, and its conditions, with given circumstances, and is not at all confined to the compatibility of the production of a thing with given circumstances.

to reasoning

Reasoning in 3. We are now prepared to understand how the mind, in its possibility is pursuit of the cognition of fact, which alone is true and subservient complete cognition, - forms and uses its knowledge of the in necessity. possible. One is often unable to determine directly, from Five steps. his knowledge of the circumstances of a case, what the truth may be respecting some point of inquiry, that is, he is unable to discover any real antecedent which, as involving a logical condition, necessitates the reality of some object conceived of. Such antecedents may exist, but he knows not where to seek for them, or, at least, has not been able to find any. In these circumstances the direct search for truth is abandoned, and the inquiry, Is the thing supposed possible? takes the place of the question, Is it necessary?

This inquiry as to possibility may be prosecuted in various ways; but when fully developed it is twofold, referring, first, to hypothetical, and then to real, possibility.

For first, if need be, we ask as to the abstract possibility of the thing, that is, its possibility without reference either to any specific circumstances or to the actual existence or non-existence of any conditions. This inquiry is to determine the ideal compossibility of the conditions, internal and external, of the object with each other, and with the necessary elements and laws of being. If any conditions be found incompatible with each other, or with any radical law of existence, there is no need of further inquiry. No matter what existing circumstances may be, the thing is impossible, and does not exist.

But if the abstract supposition do not thus involve contradiction and absurdity, our next inquiry might concern the hypothetical possibility of the thing under the given circumstances. In other words, we might ask whether the necessary conditions of the thing be possible and supposable in the case presented. Here, also, if any condition should appear thus impossible, our quest for truth would terminate.

Otherwise we should immediately pass to the second leading inquiry concerning possibility, and should ask, Is the thing really possible? Do its conditions really exist? For we assume that an attentive study of the thing under consideration has brought distinctly to view its necessary parts and other conditions. Suppose now we find that some condition of the thing does not exist, is not contained in the given circumstances. This being the case, the thing is really impossible; for a thing cannot exist so long as any one of its conditions is nonexistent. Thus, again, the possible has been our guide to the real; it has led again to the really non-existent.

But suppose, further, that every condition concerning which we can inquire is found to be a reality. We now say that, so far as we can see, the thing is really possible, and cannot be denied to exist; we can inferentially deny only the impossible. In this case reasoning in possibility enables one to reject any unfounded disbelief, that is, any unfounded belief in the non-existence of the object, the mind for the proper consideration of evidence.

- and prepares

Moreover, logical conditions, or exact antecedents, being composed

of necessary conditions, inquiry after the latter puts us better in the way of meeting with the former, or with reasons containing them; and thus, searching within and over the field of necessary conditions, we are in the way of finding conclusive antecedents, if such are discoverable.

Finally, therefore, suppose that certain conditions are found to be real, which, taken together, can belong to but one object, and that the object whose reality is in question. The inference of possibility is now replaced by the inference of fact; our inquiry terminates in the assertion of positive reality. Thus, in several ways and degrees, reasoning in possibility subserves reasoning in necessity.

The ordinary inference of the possible is concerned, almost exclusively, with real possibility and real conditions. The abstract possibility of a thing is generally known before the commencement of inquiry; and that hypothetical possibility which is limited by the given circumstances serves only to direct our search after real conditions. Those who set out to rescue the Arctic explorers had no doubt that men could exist anywhere under certain conditions; nor had they any difficulty in imagining that their long-absent countrymen might still live under those conditions, even in the most frozen and inhospitable latitudes. But their hopes and their search were based on the belief that some of those conditions were, or had been, actual, and that others might be found to exist. They knew that the expedition had been sent out in strong and well-equipped vessels, with abundant provision of clothing, food, and fuel, and with the means of obtaining such supplies as those hyperborean regions afforded. These facts were the basis of a real possibility. Still the questions were unsettled whether the ships had proved of sufficient strength, whether provisions had not been exhausted, and whether the adventurers had succeeded in pro

curing additional supplies. Let us suppose, now, that the rescuing party, in their progress, should obtain, from natives or from deposited records, evidence as to one and another of these doubtful points. Plainly their hope would be confirmed, - the possibility of timely relief would become more real; it would be based on a greater number of real conditions. Finally, should they ascertain that the explorers had been lately seen, and that they had the necessary means of living for a certain time, they would press forward in the full confidence of finding them.

Inference of 4. The explanations above given describe only the inferthe possible ence of that which we ordinarily mean by the possible. Comnot to be. monly the possible means the possible to be, just as the impossible commonly signifies the impossible to be. Sometimes, however, we speak of the possible not to be, of that whose non-existence is or would be compatible with given circumstances; and our reasoning concerning this possible has a law of its own. A thing is inferred as possible to be when its conditions, so far as considered, exist or are possible; but it is inferred as possible not to be when its conditions, so far as found existent or possible, do not constitute a logical condition. This is the law of the possibility not to be, real and hypothetical.

We see, therefore, how reasoning in possibility (whether positive or negative possibility) is closely related to reasoning in necessity

(whether positive or negative). Both modes of inference are based on the radical principle that all things exist as conditioned. Both arise from the consideration of things as conditioned; both even have a reference to logical conditions. The necessary to be is inferred directly from the existence of such a condition. The impossible, or necessary not to be, is inferred from the non-existence of one or more of those necessary conditions out of which every logical condition is constituted. The possible to be is inferred from the existence of necessary conditions when we can at the same time suppose the existence of a logical condition containing them. And the possible not to be is inferred from the existence of necessary conditions when we can suppose the non-existence of the logical condition of which they would be parts. These remarks show how the possible to be leads towards the necessary, and how the possible not to be leads towards the impossible.

Intermedi

CHAPTER XXII.

CONTINGENCY AND PROBABILITY.

1. THE only definition of possibility which seems to ate possibil- cover every case is that which makes it the existential ity defined. compatibility of one thing with others. When the existence of a thing, so far as relates to any of its necessary conditions, is compatible with given circumstances, we have the possible to be; and when its non-existence, notwithstanding the existence of some conditions, is compatible with given circumstances, we have the possible not to be. When all the necessary conditions of a thing exist, it is both perfectly possible to be and necessary to be; and when any of these conditions do not exist, it is both perfectly possible not to be and impossible to be. But when some of the conditions exist, and we have no reason to believe the others existent or to believe them nonexistent, we say that the thing is possible either to be or not to be. This, too, is the possibility most frequently considered.

When possibility has this double character it may be called intermediate, as lying between those possibilities, positive and negative, which belong to facts, and which consist with necessity and impossibility. This intermediate possibility is of the same nature with that already described as partial, excepting only that it has a doubleness, and looks in two directions.

The above statements, for the sake of simplicity, directly refer only to real possibility, in which conditions are not merely supposed, but asserted to exist. Similar statements might be made in regard to hypothetical possibility; which, however, we need not specifically discuss. Intermediate possibility is the primary basis or ground Contingency for judgments of probability; and when it is thought of as such, it is styled contingency. For it could not be probable that there will be frost in Clinton on the 4th of March, were it not possible both that there should be and that there should not be frost

in Clinton on that day. Contingency, therefore, is an intermediate possibility, for it belongs to that which both may be and may not be.

Yet contingency, as we commonly think of it, does not include all possibility of this kind, but only such as may be used as a basis for a judgment of probability. For a thing contingent, although not therein also probable, yet is possible in such a mode as to render the inquiry reasonable whether it be probable or not. Contingency, as having this suggestive force, might be called a strong possibility.

Were a beautiful poem published anonymously, search would not be made among men in general for its author, but only among a certain class of men; and although, in an extreme and abstract sense, one might say that it is contingent to a man to write poetry, yet, for the purposes of inquiry, we would limit this contingency to persons poetically gifted. In this way two forms of possibility may be distinguished, both of which might indeed be termed contingency, but the latter of which specially deserves the name.

be strong or

antecedent

The antece- The origin of this distinction is to be found in the dent of pos- diverse character of the conditions on which the possibilisibility may ties depend. We have seen that a thing is possible with weak. The reference to any necessary condition of its existence when former is the that condition exists; therefore such a condition, as existing, may be termed an antecedent of possibility. But of such antecedents there are two kinds, one weak, and the other strong. These arise, respectively, according as the antecedent of possibility does or does not approximate to an antecedent of necessity, or rather to that logical condition which every antecedent of necessity involves.

of contingency.

We have seen that every logical condition is composed of necessary conditions. It is also clear that any condition which is complex is also composed of such conditions; for any condition in all its parts is necessary to that which it conditions. Now a condition which, though falling short of a logical condition, so resembles some such condition already known to us as immediately to suggest it to our minds, may be called a strong condition, because, in the absence of any conclusive information, it suggests the thought, "The whole logical condition may exist, and the consequent therefore may be a fact.” But a condition which does not thus resemble a logical condition may be called weak; for it suggests no necessitating condition, and affords no basis or starting-point for search.

If a criminal escaped from justice, it would not excite inquiry on the part of the proper officers to be told that there was a man in such or such a place. Although this would be a necessary condition of the location of any criminal, the possibility resting on it would not suggest any logical necessitant. But if they should learn that a person resembling the criminal somewhat had made his appearance in a certain city just after the time of the escape, they would say, " Possibly he is the man.' In this case there would be something more than abstract theoretical possibility; there would be a strong practical possibility, a contingency, attaching itself to the man heard from, that he may be the criminal in question. The mere existence of a

man somewhere is the antecedent of possibility; that of the man resembling the criminal is the antecedent of contingency. The latter, by the addition of only a few particulars, may become a logical necessitant; and the thought of such particulars is immediately suggested to the mind. ·

At the same time the antecedent of contingency does not of itself establish a probability, but only a strong or suggestive possibility, a mere indeterminate chance. The question whether the chances for the supposition be one in ten or one in ten thousand, or whether they can be found to have any definite ratio to the chances against the supposition, is to be resolved by further considerations.

Probable

two ways.

2. This indeterminate judgment of contingency, however, judgment passes into a judgment of probability when the antecedent originates in of contingency does not merely suggest the idea of a consequent as possible to be or not to be, but is also followed by an expectation, of greater or less strength, that a thing really is or is not; and this result may arise in one or other of two ways. Sometimes we immediately perceive the likelihood of a thing without using the conception of the chances, or individual possibilities, for and against the supposition; while at other times we employ the ratio of the chances as the basis of our judgment. Probability, when ascertained by the latter of these methods, might be called reasoned; and when determined by the former, unreasoned. Both probabilities, indeed, are asserted properly and in accordance with reason; but the unreasoned mode does not require that degree of mental strength and penetration which the estimation of chances does, and may be within the apprehension of the higher order of brutes.

And

So long as the officers knew only that a man resembled the escaped criminal in some general way, - for example, in being six feet high and having black hair, — this would not be a ground for expectation, but only for inquiry. Many men might answer that description. But if additional information came that the person heard from was like the criminal in having lost an eye or in being pock-marked, or in both particulars, they would say, "He is probably the man." their reason for so judging would not be that in a large majority of previous cases such an aggregate of marks had led to the right man, and that they could therefore consciously refer to a rule of probability, but simply that they found it easy to suppose that the marks reported would be so supplemented by others as to furnish a logical Condition, or positive proof, of the correctness of their conjecture. Because we often expect things in this way when we perceive a strong resemblance between some given antecedent of contingency and a conceived-of antecedent of necessity, probability is frequently called likelihood.

In unreasoned probability, from the consideration of one real or given antecedent of contingency, we may either assert only one consequent as probable, and its contradictory as improbable, or we may assert several alternatives of different degrees of probability. For example, a man looking at the clouds might say it is probable that there will be a shower within fifteen minutes, and improbable that there will not be one; or he might judge that either rain or snow or sleet will fall within that time, and assign different degrees of likeli