Contrary Events

A contrariety of past events might make us hesitate by producing an imperfect transition from the present impression to the related idea.

When the conjunction of 2 objects is frequent but not constant, the mind passes from one object to the other.

But when the union is uninterrupted and all the instances that we have experienced are uniform and of a piece, this transition becomes habitual.

In our life, we find that our constant perseverance creates a strong tendency to continue, even if there are inferior habits proportional to the inferior uniformity of our conduct.

This principle sometimes takes place to produce those inferences we draw from contrary phenomena.

But ths principle does not commonly influence the mind in this species of reasoning.

When we only follow the mind’s habitual determination, we make the transition instantly without any reflection.

This habit does not depend on any deliberation.

It operates immediately without allowing any time for reflection.

But we have few instances of this method in our probable reasonings.

We have even fewer than in those derived from the uninterrupted conjunction of objects.

In this method of reasoning, we knowingly take into consideration the contrariety of past events.

We compare the different sides of the contrariety.

We carefully weigh the experiments we have on each side.

We may conclude that our reasonings of this kind do not arise directly from the habit.

It arises instead in an oblique way which we must now explain.

When an object is attended with contrary effects, we:

• judge of them only by our past experience, and
• always consider its subsequent effects as possible.

Past experience regulates our judgment on the possibility and probability of these effects.

We always esteem the effect which has been the most common, as the most likely.

We consider:

1. The reasons which determine us to make the past a standard for the future, and
2. How we extract a single judgment from a contrariety of past events.

The supposition that the future resembles the past, is not founded on arguments.

• It is derived entirely from habit.*

Habit makes us expect the same train of objects, which we have been accustomed to, for the future.

Consequently, the first impulse of the imagination in this species of reasoning is endowed with the same qualities.

When we consider past experiments and find them of a contrary nature, this determination, though full and perfect in itself, presents us with no steady object.

It offers us a number of disagreeing images in a certain order and proportion.

The first impulse, therefore:

• is broken into pieces, and
• diffuses itself over all those images which has an equal share of that force and vivacity derived from the impulse.

Any of these past events may again happen.

We judge that, when they do happen, they will be mixed in the same proportion as in the past.

If our intention, therefore, is to consider the proportions of contrary events in many instances, the images presented by our past experience must:

• remain in their first form, and
• preserve their first proportions.

Suppose through time, I find that only 19 ships return out of 20 that go to sea.

I see at present 20 ships that leave the port.

I transfer my past experience to the future.

I expect 19 of these ships as returning safely with one perishing.

We frequently run over past events to create a judgment on a single event which appears uncertain.

This consideration must:

• change the first form of our ideas, and
• draw together the divided images presented by experience, since we refer the outcome of that event to the imagination.

A superior number are supposed to concur on one side.

These agreeing images:

• unite together, and
• render the idea more strong and lively than: a mere fiction of the imagination, and any idea supported by fewer experiments.

Each new experiment is a new stroke of the pencil.

Each stroke bestows an additional vivacity on the colours without multiplying or enlarging the figure.

This operation of the mind has been explained in the section on the probability of chance.

Every past experiment is a kind of chance.

We are uncertain whether the object will exist conformable to one experiment or another.

This is why everything that has been said on the one subject is applicable to both.

Thus on the whole, contrary experiments produce an imperfect belief by:

• weakening the habit, or
• dividing and afterwards joining that perfect habit.

That habit makes us conclude that instances we have no experience of, must resemble the instances which we have experience of.