An abridgment of Mr. Locke's Essay concerning humane [sic] understanding

CHAP. III. Of the Extent of Humane Knowledge.

FRom what has been said concerning Knowledge, it follows that, First, We can have no Knowledge farther than we have Ideas.

Secondly, That we have no Knowledge farther than we can have Perception of that Agreement or Disagreement of our Ideas, either by Intuition, Demonstration, or Sensation.

Thirdly, We cannot have an Intuitive Knowledge that shall extend it self to all our Ideas, and all that we would know about them; because we cannot examine and perceive all the Relations they have one to another, by Juxta-position, or an immediate Comparison one with another. Thus we cannot intuitively perceive the equality of two Extensions, the diffe∣rence of whose Figures makes their parts uncapable of an exact and immediate ap∣plication.

Fourthly, our rational Knowledge can not reach to the whole extent of our Ideas; because between two different Ideas we would examine, we cannot always find such proofs, as we can connect one to ano∣ther, with an Intuitive Knowledge in all the parts of the Deduction.

Fifthly, Sensitive Knowledge reaching no farther than the Existence of Things actually present to our Senses, is yet much narrower than either of the for∣mer.

Sixthly, From all which it is evident, that the extent of our Knowledge, comes not only short of the Reality of Things, but even of the extent of our own Ideas. We have the Ideas of a Square, a Circle and Equality, and yet perhaps shall never be able to find a Circle equal to a Square.

The Affirmations or Negations we make concerning the Ideas we have, be∣ing reduced to the four Sorts above-men∣tioned, viz. Identity, Co-existence, Relati∣on, and Real Existence; I shall examine how far our Knowledge extends in each of these.

First, As to Identity and Diversity, our Intuitive Knowledge is as far extended as our Ideas themselves; and there can

be no Idea in the Mind, which it does not presently by an Intuitive Knowledge, perceive to be what it is, and to be dif∣ferent from any other.

Secondly, As to the Agreement or Dis∣agreement of our Ideas in Co-existence: in this our Knowledge is very short, thô in this consists the greatest and most ma∣terial part of our Knowledge, concern∣ing Substances: for our Ideas of Substances being as I have shewed, nothing but cer∣tain Collections of Simple Ideas, co-existing in one Subject, (Our Idea of Flame for In∣stance, is a Body hot, Luminous and mo∣ving upward.) When we would know any thing farther concerning this or any other sort of Substance, What do we but en∣quire what other Qualities or Powers these Substances have or have not? which is nothing else but to know, what other Simple Ideas do, or do not Co-exist with those that make up that Complex Idea. The reason of this is, because the Simple Ideas which make up our Complex Ideas of Substances, have no visible neces∣sary Connexion or Inconsistence with o∣ther Simple Ideas, whose co-existence with them we would inform our selves about. These Ideas being likewise for the most

part Secundary Qualities, which depend up∣on the Primary Qualities of their minute or insensible Parts, or on something yet more remote from our Comprehension; it is impossible we should know which have a necessary Union, or Inconsistency one with another, since we know not the root from whence they spring, or the Size, Figure, and Texture of Parts on which they depend, and from which they result.

Besides this, there is no discoverable Connexion between any Secundary Qua∣litie, and those Primary Qualities that it depends on. We are so far from know∣ing what Figure, Size or Motion pro∣duces, (for Instance) A Yellow Colour, or Sweet Taste, or a Sharp Sound, that we can by no means conceive how any Size, Figure, or Motion can possibly produce in us the Idea of any Colour, Taste or Sound whatsoever; and there is no conceiva∣ble Connexion between the One and the Other.

Our Knowledge therefore of Co-ex∣istence reaches little farther than Expe∣rience. Some few indeed of the Primary Qualities have a necessary Dependance, and visible Connexion one with another:

As Figure necessarily supposes Extension: receiving or communicating Motion by Im∣pulse, supposes Solidity. But Qualities Co-existent in any Subject, without this Dependance and Connexion, cannot cer∣tainly be known to Co-exist any farther, than Experience by our Senses informs us. Thus, thô upon trial we find Gold Yellow, Weighty, Malleable, Fusible and Fixed, yet because none of these have any evident Dependance, or necessary Con∣nexion with the other; we cannot cer∣tainly know, that where any Four of these are, the Fifth will be there also, how highly probable soever it may be: But the highest degree of Probability, amounts not to Certainty; without which there can be no true Knowledge: For this Co-existence can be no farther known, then it is perceived; and it cannot be percei∣ved, but either in particular Subjects, by the observation of our Senses; or in ge∣neral, by the necessary Connexion of the Ideas themselves.

As to Incompatibility, or Repugnancy to Co-existence, we may know that any Sub∣ject can have of each sort of Primary Qualities, but One particular at once. One Extension, One Figure; and

so of sensible Ideas peculiar to each Sense: For whatever of each kind, is present in any Subject, excludes all other of that Sort; for Instance, One Subject cannot have Two Smells, or Two Colours at the same time.

As to Powers of Substances, which makes a great part of our Enquiries about them, and is no inconsiderable branch of our Knowledge: Our Knowledge as to these reaches little farther than Experience; be∣cause they consist in a Texture and Moti∣on of Parts, which we cannot by any means come to discover; and I doubt whether with those Faculties we have, we shall ever be able to carry our general Knowledge much farther in this part. Experience is that which in this part we must depend on; and it were to be wish∣ed that it were improved: we find the Advantages some Mens generous pains, have this way brought to the stock of Natural Knowledge. And if others, espe∣cially the Philosophers by Fire who pretend to it, had been so wary in their Obser∣vations, and sincere in their Reports, as those who call themselves Philosophers ought to have been: our acquaintance with the Bodies here about us, and our

insight into their Powers and Operations had been yet much greater.

As to the Third Sort the Agreement or Disagreement of our Ideas in any other Rela∣tion: This is the largest field of Know∣ledge, and it is hard to determine how far it may extend. This part depending on our Sagacity in finding intermediate Ideas, that may shew the Habitudes and Relations of Ideas; It is an hard matter to tell when we are at an end of such Discoveries. They that are ignorant of Algebra, cannot imagine the Wonders in this kind, are to be done by it: and what farther Improvements and Helps, advantageous to other parts of Know∣ledge, the Sagacious Mind of Man may yet find out, it is not easy to determine. This at least I believe that the Ideas of Quantity, are not those alone that are ca∣pable of Demonstration and Knowledge: and that other, and perhaps more useful parts of Contemplation, would afford us Certainty, if Vices, Passions, and domi∣neering Interests, did not oppose or me∣nace Endeavours of this kind.

The Idea of a Supream Being, Infinite in Power, Goodness, and Wisdom, whose Workmanship we are, and on whom we

depend; and the Idea of our Selves, as understanding rational Creatures, would I suppose, if duly considered, afford such Foundations of our Duty, and Rules of Action, as might place Morality among the Sciences capable of Demonstration: wherein I doubt not but from Principles as Incontestable as those of the Mathema∣ticks, by necessary Consequences, the measure of Right and Wrong might be made out, to any one that will apply himself with the same Indifferency and Attention to the One, as he does to the Other of these Sciences. The Relations of other Modes may certainly be percei∣ved as well as those of Number, and Ex∣tension. Where there is no Property, there is no Injustice, is a Proposition as certain as any Demonstration in Euclid: for the Idea of Property, being a right to any thing; and the Idea of Injustice, being the invasion or violation of that Right: it is evident that these Ideas being thus established, and these Names annexed to them, I can as certainly know this Pro∣position to be true, as that a Triangle has three Angles equal to Two right ones. Again, No Government allows absolute Liberty. The Idea of Government being the establish∣ment

of Society upon certain Rules or Laws, which require Conformity to them; and the Idea of Absolute Liberty, being for any one to do whatever he pleases, I am as capable of being certain of the Truth of this Proposition, as of any in Mathe∣maticks.

What has given the advantage to the Ideas of Quantity, and made them thought more capable of Certainty and Demon∣stration, is,

First, That they can be represented by sensible Marks, which have a nearer Correspondence with them, than any Words or Sounds. Diagrams drawn on Paper, are Copies of the Ideas, and not liable to the uncertainty that Words carry in their Signification. But we have no sensible Marks that resemble our Moral Ideas, and nothing but Words to express them by; which thô, when written, they remain the same; yet the Ideas they stand for, may change in the same Man; and it is very seldom that they are not diffe∣rent in different Persons.

Secondly, Moral Ideas are commonly more Complex than Figures: whence these two Inconveniencies follow: First, That their Names are of more uncertain

Signification; the precise collection of Simple Ideas they stand for, not being so easily agreed on, and so the sign that is used for them in Communication al∣ways, and in Thinking often, does not steadily carry with it the same Idea. Se∣condly, The Mind cannot easily retain those precise Combinations so exactly and perfectly as is necessary; in the examina∣tion of the Habitudes and Correspon∣dencies, Agreements or Disagreements of several of them one with another, espe∣cially where it is to be judged of by long Deductions, and the intervention of se∣veral other Complex Ideas, to shew the Agreement' or Disagreement of two re∣mote ones.

One part of these Disadvantages in Moral Ideas, which has made them be thought not capable of Demonstration, may in a good measure be remedied by Definitions, setting down that collection of Simple Ideas which every Term shall stand for, and then using the Terms stea∣dily and constantly for that precise Col∣lection.

As to the Fourth sort of Knowledge, viz. of the real actual existence of Things, we have an Intuitive Knowledge of our

own Existence: a Demonstrative Knowledge, of the Existence of God; and a Sensitive Knowledge of the Objects that present them∣selves to our Senses.

From what has been said we may dis∣cover the Causes of our Ignorance, which are chiefly these Three; First, want of Ideas; Secondly, Want of a discoverable Connexion between the Ideas we have. Thirdly, Want of tracing and examining our Ideas.

First, There are some things we are ignorant of for want of Ideas. All the Simple Ideas we have, are confined to the observation of our Senses, and the ope∣rations of our own Minds, that we are conscious of in our Selves. What other Ideas it is possible other Creatures may have, by the assistance of other Senses and Faculties more or perfecter than we have, or different from ours, it is not for us to determine; but to say or think, there are no such, because we conceive nothing of them, is no better an Argu∣ment, than if a blind Man should be po∣sitive in it, that there was no such thing as Sight and Colours, because he had no manner of Idea of any such thing. What Faculties therefore other species of

Creatures have to penetrate into the Na∣ture and inmost constitutions of Things, we know not. This we know, and cer∣tainly find, that we want other views of them, besides those we have to make dis∣coveries of them more perfect. The In∣tellectual and Sensible World are in this perfectly alike, that the parts which we see of either of them, hold no proporti∣on with that we see not, and whatsoever we can reach with our Eyes, or our Thoughts of either of them, is but a point, almost nothing, in comparison of the rest.

Another great cause of Ignorance, is the want of Ideas that we are capable of. This keeps us in ignorance of Things we conceive capable of being known. Bulk, Figure and Motion we have Ideas of: yet not knowing what is the particular Bulk, Motion and Figure of the greatest part of the Bodies of the Universe, we are ignorant of the several Powers, Effi∣cacies, and ways of Operation, where∣by the effects we daily see, are produced. These are hid from us in some things, by being too Remote, in others by being too Minute.

When we consider the vast distance of the known and visible parts of the World, and the reasons we have to think that what lies within our Ken, is but a small part of the immense Universe; we shall then discover an huge abyss of Ig∣norance. What are the particular Fa∣bricks of the great Masses of Matter, which make up the whole stupendous frame of corporeal Beings, how far they are extended, and what is their motion, and how continued, and what influence they have upon one another, are con∣templations that at first glimpse our Thoughts lose themselves in. If we confine our Thoughts to this little Can∣ton, I mean this System of our Sun, and the grosser Masses of Matter that visibly move about it; What several sorts of Vegetables, Animals, and Intellectual corporeal Beings, infinitely different from those of our little spot of Earth, may probably be in other Planets, to the know∣ledge of which, even of their outward Figures, and Parts, we can no way at∣tain, whilst we are confined to this Earth, there being no natural means, either by Sensation or Reflection, to convey their certain Ideas into our Minds?

There are other Bodies in the Universe, no less concealed from us by their Mi∣nuteness. These insensible Corpuscles be∣ing the active parts of Matter, and the great instruments of Nature, on which depend all their Secundary Qualities and Operations, our want of precise distinct Ideas, and their Primary Qualities, keeps us in incurable Ignorance of what we desire to know about them. Did we know the Mechanical Affections of Rhu∣barb or Opium, we might as easily ac∣count for their Operations of Purging and causing Sleep, as a Watch-maker can for the Motions of his Watch. The dissol∣ving of Silver in Aqua fortis, or Gold in Aqua Regia, and not Vice versâ, would be then perhaps no more difficult to know, than it is to a Smith, to under∣stand why the turning of one Key, will open a Lock, and not the turning of an∣other. But whilst we are destitute of Senses, acute enough to discover the minute Particles of Bodies, and to give us Ideas of their Mechanical Affections, we must be content to be ignorant of their Properties and Operations; nor can we be assured about them any far∣ther, than some few Trials we make, are

able to reach: but whether they will succeed again another time, we cannot be certain. This hinders our certain Knowledge of Universal Truths concern∣ing Natural Bodies: and our Reason car∣ries us herein very little beyond par∣ticular Matter of Fact. And therefore I am apt to doubt, that how far soever Humane Industry may advance useful and Experimental Philosophy in Physical Things, yet Scientifical will still be out of our reach; because we want perfect and adequate Ideas of those very Bodies which are nearest to us, and most under our Command.

This at first sight shews us how dis∣proportionate our Knowledge is to the whole extent, even of Material Beings: to which, if we add the Consideration of that infinite number of Spirits that may be, and probably are, which are yet more remote from our Knowledge, where∣of we have no cognizance: we shall find this cause of Ignorance, conceal from us in an impenetrable Obscurity, almost the whole Intellectual World: a greater Cer∣tainly, and more beautiful World than the material. For bating some very few Ideas of Spirit, we get from our own

Mind by Reflection, and from thence the best we can collect, of the Father of all Spirits, the Author of them, and us, and all Things: we have no certain In∣formation, so much as of the Existence of other Spirits but by Revelation: much less have we distinct Ideas of their diffe∣rent Natures, States, Powers, and seve∣ral Constitutions, wherein they agree or differ one from another, and from us. And therefore in what concerns their dif∣ferent Species, and Properties, we are under an absolute Ignorance.

The Second cause of Ignorance is the want of discoverable Connexion between those Ideas we have; where we want that, we are utterly incapable of Universal and Certain Knowledge; and are as in the for∣mer case, left only to Observation and Ex∣periment. Thus the Mechanical Affecti∣ons of Bodies, having no affinity at all with the Ideas they produce in us; we can have no distinct Knowledge of such operations beyond our Experience; and can reason no otherwise about them, than as the effects or appointment of an Infi∣nitly Wise Agent, which perfectly surpass our Comprehensions.

The operation of our Minds upon our Bodies, is as unconceivable. How any Thought should produce a Motion in Bo∣dy, is as remote from the nature of our Ideas, as how any Body should produce any Thought in the Mind. That it is so, if Experience did not convince us, the consideration of the Things themselves, would never be able in the least to dis∣cover to us.

In some of our Ideas, there are certain Relations, Habitudes, and Connexions, so visibly included in the nature of the Ideas themselves, that we cannot con∣ceive them separable from them by any Power whatsoever: In these only we are capable of Certain and Universal Knowledge. Thus the Ideas of a right lined Triangle, necessarily carries with it, an Equality of its Angles to two right ones. But the coherence and continuity of the Parts of Matter; the production of Sen∣sation in us, of Colours and Sounds, &c. by Impulse, and Motion, being such wherein we can discover no natural Con∣nexion with any Ideas we have, we can∣not but ascribe them to the arbitrary Will and good Pleasure of the wise Ar∣chitect.

The Things that we observe constant∣ly to proceed regularly, we may con∣clude do act by a Law set them; but yet by a Law that we know not; whereby, thô Causes work steadily, and effects con∣stantly flow from them; yet their Con∣nexions and Dependencies being not dis∣coverable in our Ideas, we can have but an experimental Knowledge of them. Several Effects come every day within the notice of our Senses, of which we have so far Sensitive Knowledge. But the Causes, Manner and Certainty of their Production, we must for the fore∣going reasons be content to be ignorant of. In these we can go no farther than particular Experience informs us of matter of Fact, and by Analogy, guess what Effects the like Bodies are upon other Tryals like to produce. But as to per∣fect Science of Natural Bodies (not to mention Spiritual Beings) we are, I think, so far from being capable of any such thing, that I conclude it lost labour to seek after it.

The Third cause of Ignorance is our Want of tracing those Ideas we have, or may have; and finding out those inter∣mediate Ideas which may shew us what

Habitude of Agreement or Disagreement, they may have one with another: and thus many are ignorant of Mathematical Truths, for want of application in enqui∣ring, examining, and by due ways com∣paring those Ideas.

Hitherto we have examined the Ex∣tent of our Knowledge, in respect of the several sorts of Beings that are. There is another Extent of it, in respect of Uni∣versality, which will also deserve to be considered; and in this regard our Knowledge follows the Nature of our Ideas. If the Ideas are Abstract, whose Agreement or Disagreement we perceive, our Knowledge is Universal. For what is known of such general Ideas, will be true of every particular thing in which that Essence, that is, that Abstract Idea is to be found: And what is once known of such Ideas, will be perpetually, and for ever true. So that as to all general Knowledge, we must search and find it only in our own Minds: and it is only the examining of our own Ideas, that furnishes us with the Truths belong∣ing to Essences of Things (that is, to Abstract Ideas) that are Eternal, and are to be found out by the Contempla∣tion

only of those Essences; as the Ex∣istence of Things is to be known only from Experience. But I shall say more of this in the following Chapters, where I shall speak of General, and Rèal Know∣ledge.