The Idea of Identity is Caused by the Resemblance of Perceptions

by David Hume

Our idea of the personal identity which produces thought or imagination can be explained by our idea on the personal identity of plants and animals.

There is a great analogy between:

• the personal identity of plants and animals which produces thought or imagination, and
• the personal identity of a person.

We have a distinct idea of an object that remains unchanged through time.

We call this idea ‘identity’ or ‘sameness’.

We also have a distinct idea of several related objects existing in succession.

This gives us a perfect a notion of ‘diversity’, as if those objects were not related.

These two ideas of ‘sameness’ and ‘diversity’ are perfectly distinct and even contrary.

Yet in our common way of thinking, they are confounded with each other.

The action of the mind that comes up with the idea of sameness and the idea of diversity feels almost the same.

The effort required in both is the same. But the similarity of the successive objects in our idea of diversity makes us consider it as one continued object. This resemblance is the cause of the confusion and mistake.

It makes us replace the diversity of objects with the notion of identity. We might properly think of the object as different for a split second.

But in the next moment, we always assign an identity to that object. Our propensity to this mistake is so great.

We fall into it before we are aware. We incessantly correct ourselves by reflection return to a more accurate method of thinking. Yet we cannot sustain our philosophy for long, or take off this bias from the imagination. Our last resource is to yield to it.

We boldly assert that these diverse but related objects are the same. In order to justify this absurdity to ourselves, we often feign some new and unintelligible principle that: connects the objects together, and prevents their interruption or variation.

Thus, we feign the continued existence of the perceptions of our senses, to remove the interruption.

We run into the notion of a soul, self, and substance to disguise the variation. If we did not do so, our propension to confound identity with relation would be so great. We would imagine [Footnote 10] something unknown and mysterious, connecting the parts, beside their relation. This is the case with the identity that we ascribe to plants. Even when this does not take place, we still feel a propensity to confound these ideas, even if we: are not able fully to satisfy ourselves in that, nor can we find anything invariable and uninterrupted to justify our notion of identity. Footnote 10:

If the reader wants to see how a great genius may be influenced by these seemingly trivial and vulgar principles of the imagination, let him read my Lord Shaftsbury’s reasonings on: the universe’s uniting principle, and the identity of plants and animals (See his Moralists, or Philosophical Rhapsody). Thus the controversy on identity is not merely a dispute of words.

When we improperly ascribe ‘identity’ to diverse objects, our mistake is not confined to the idea of identity.

It is commonly attended with a fiction of something:

• invariable and uninterrupted, or
• mysterious and inexplicable, or
• at least with a propensity to such fictions.

This hypothesis is proven by showing from daily experience that diverse objects which continue the same, are only those that have parts successively connected by resemblance, contiguity, or causation.

When our minds perceive such a succession in objects, we assign it a notion of diversity. We only ascribe identity to it by mistake. The relation of the parts of the object which leads us into this mistake, is merely a quality which makes our minds easily easy transition from one to another. The error arises only because of the resemblance which this act of the mind on thinking about a noncontinuous object bears to the act of the mind thinking about a continuous object. Our chief business then is to prove that all objects that we think as having an identity, are objects that have a succession of related objects, without observing their lack of change and lack of continuity. We Assign a Change in Identity Based on Our Perception of the Change Relative to the Whole A mass of matter with contiguous and connected parts, is placed before us.

We attribute a perfect identity to this mass, provided all the parts are unchanged. But if some very small part were added to or subtracted from the mass, it would absolutely destroy the whole’s identity, strictly speaking. Yet we seldom think so accurately. We say the mass is the same despite this trivial change. The thought passes so smoothly and easily from the object before the change to the object after it. We do not perceive the transition. We imagine that it is just a continued survey of the same object. A very remarkable circumstance attends this experiment.

The change of any considerable part in a mass of matter destroys the whole identity. But we must measure the greatness of the part by its proportion to the whole, and not absolutely. The addition or reduction of a mountain would not be enough to produce a diversity in a planet, but the change of a very few inches can destroy the identity of some bodies. This means that objects break or interrupt the continuity of the mind’s actions not according to the size of the objects, but according to their proportion to each other. This interruption makes an object cease to appear the same. The uninterrupted progress of the thought which constitutes the imperfect identity. This may be confirmed by another phenomenon.

A change in any considerable part of a body destroys its identity. But it is remarkable that where the change is produced gradually and insensibly, we are less apt to ascribe to it the same effect. The only reason is that when the mind follows the successive changes of the body: it feels an easy passage from surveying its condition in one moment to the view it in another, and it perceives no interruption in its actions. From this continued perception, it ascribes a continued existence and identity to the object. We might use precautions in: introducing the changes gradually, and making them proportional to the whole. We make a scruple of ascribing identity to such different objects, when the changes finally become considerable.

We may induce the imagination to advance a step further by producing a: reference of the parts to each other, and combination to some common end or purpose. A ship, with a big part changed by frequent repairs, is still the same ship. The difference of the materials does not hinder us from ascribing an identity to it. The common end, in which the parts conspire: is the same under all their variations, and affords an easy transition of the imagination from one bodily situation to another. But this is still more remarkable when we:

add a sympathy of parts to their common end, and suppose that they bear to each other the reciprocal relation of cause and effect in all their operations. This is the case with all plants and animals.

Their several parts have a: reference to some general purpose, and mutual dependence on, and connection with each other. Tree

After a few years, both plants and animals undergo a total change.

Yet we still ascribe identity to them, while their form, size, and substance are entirely altered. This is the effect of so strong a relation. An oak that grows from a small plant to a large tree is still the same oak. Though none of its parts are the same. A baby becomes a man. He is sometimes fat or lean without any change in his identity.