Thus perception, in this primary sense, is perception of the settled world in the past as constituted by its feeling-tones, and as efficacious by reason of those feeling- tones. Perception, in this sense of the term, will be called ‘perception in the mode of causal efficacity.’ Memory is an example of perception in this mode. For memory is perception relating to the data from some historic route of ultimate percipient subjects M,, M2, Ms, etc., leading up to M which is the memorizing percipient.
It is evident that ‘perception in the mode of causal
efficacy’ is not that sort of perception which has received
chief attention in the philosophical tradition. Philoso-
phers have disdained the information about the universe
obtained through their visceral feelings, and have con-
centrated on visual feelings.
What we ordinarily term our visual perceptions are
the result of the later stages in the concrescence of the
percipient occasion. When we register in consciousness
our visual perception of a grey stone, something more
than bare sight is meant. The ‘stone’ has a reference
Organisms and Environment 185
to its past, when it could be used as missile if small enough, or as a seat if large enough. A ‘stone’ has cer- tainly a history, and probably a future. It is one of the elements in the actual world which has got to be referred to as an actual reason and not as an abstract potentiality. But we all know that the mere sight involved, in the perception of the grey stone, is the sight of a grey shape contemporaneous with the percipient, and with certain spatial relations to the percipient, more or less vaguely defined. Thus the mere sight is confined to the illustra- tion of the geometrical perspective relatedness, of a cer- tain contemporary spatial region, to the percipient, the illustration being effected by the mediation of ‘grey.’ The sensum ‘grey’ rescues that region from its vague confusion with other regions.
Perception which merely, by means of a sensum, res-
cues from vagueness a contemporary spatial region, in
respect to its spatial shape and its spatial perspective
from the percipient, will be called ‘perception in the
mode of presentational immediacy.’
Perception in this mode has already been considered
in Part II, Chapter II. A more elaborate discussion of
it can now be undertaken.* The definition, which has
just been given, extends beyond the particular case of
sight. The unravelling of the complex interplay between
the two modes of perception—causal efficacy and presen-
tational immediacy is one main problem of the theory of
perception.© The ordinary philosophical discussion of
perception is almost wholly concerned with this interplay,
and ignores the two pure modes which are essential for
its proper explanation. The interplay between the two
modes will be termed ‘symbolic reference.’
“ Also of subsequent discussions in Parts III and IV.
5 Cf. my Barbour-Page lectures, Symbolism, Its Meaning and Impor- tance, delivered at the University of Virginia, April, 1927, Macmillan. Another discussion of this question is there undertaken, with other illustrations. Cf. also Professor Norman Kemp Smith’s Prolegomena to an Idealist Theory of Knowledge, Macmillan, 1924,
186 Process and Reality
Such symbolic reference is so habitual in human experi- ence that great care is required to distinguish the two modes. In order to find obvious examples of the pure mode of causal efficacy we must have recourse to the viscera and to memory; and to find examples of the pure mode of presentational immediacy we must have recourse to so-called ‘delusive’ perceptions. For example, the image of a grey stone as seen in a mirror illustrates the space behind the mirror; the visual delusions arising from some delirium, or some imaginative excitement, illustrate surrounding spatial regions; analogously for the double-vision due to maladjustment of the eyes; the sight at night, of the stars and nebulae and Milky Way, illustrates vague regions of the contemporary sky; the feelings in amputated limbs illustrate spaces beyond the actual body; a bodily pain, referred to some part not the cause of the disorder, illustrates the painful region though not the pain-giving region. All these are per- fectly good examples of the pure mode of presentational immediacy.
The epithet ‘delusive,’ which fits many, if not all, of
these examples of presentational immediacy, is evidence
that the mediating eternal object is not to be ascribed
to the donation of the perceived region. It must have
acquired its ingression in this mode from one of the
originative phases of the percipient occasion. To this
extent, the philosophy of organism is in agreement with
the seventeenth-century doctrine of primary and second-
ary qualities, the mediating eternal object being, in this
mode of ingression, a secondary quality. But in the
philosophy of organism the doctrine does not have
the consequences which follow in the earlier philoso-
phies.
The account of perception in the pure mode of pre-
sentational immediacy, which has just been given, agrees
absolutely with Descartes’ doctrine of perception in gen-
eral, so far as can be Judged from his arguments which
presuppose perception, and putting aside a few detached
Organisms and Environment 187
passages wherein he comes near to the doctrine of ‘objectification’ and near to Locke’s second doctrine of ‘ideas determined to particular existents.’ Anyhow, his conclusion immediately follows that, in perception, thus described, all that is perceived is that the object has extension and is implicated in a complex of extensive relatedness with the animal body of the percipient. Part of the difficulties of Cartesian philosophy, and of any philosophy which accepts this account as a complete account of perception, is to explain how we know more than this meagre fact about the world although our only avenue of direct knowledge limits us to this barren residium. Also, if this be all that we perceive about the physical world, we have no basis for ascribing the origi- nation of the mediating sensa to any functioning of the human body. We are thus driven to the Cartesian dual- ity of substances, bodies and minds. Perception is to be ascribed to mental functioning in respect to the barren extensive universe. We have already done violence to our immediate conviction by thus thrusting the human body out of the story; for, as Hume himself declares, we know that we see by our eyes, and taste by our palates. But when we have gone so far, it is inevitable to take a further step, and to discard our other conviction that we are perceiving a world of actual things within which we find ourselves. For a barren, extensive world is not really what we mean. We thus reduce perceptions to consciousness of impressions on the mind, consisting of sensa with ‘manners’ of relatedness. We then come to Hume, and to Kant. Kant’s philosophy is an endeavour to retrieve some meaning for the two convictions which we have successively ‘discarded. We have noted that Locke wavers in his account of perception, so that in the earlier portion of his Essay he agrees with Hume, and in the later portion with the philosophy of organism. We have also noted that Hume is inconsistent to the extent of arguing from a conviction which is discarded in his philosophy.
188 Process and Reality
Presentational immediacy illustrates the contemporary world in respect to its potentiality for extensive subdivi- sion into atomic actualities and in respect to the scheme of perspective relationships which thereby eventuates. But it gives no information as to the actual atomization of this contemporary ‘real potentiality.’ By its limita- tions it exemplifies the doctrine, already stated above, that the contemporary world happens independently of the actual occasion with which it is contemporary. This is in fact the definition of contemporaneousness (cf. Part II, Ch. II, Sect. I); namely, that actual occasions, A and B, are mutually contemporary, when A does not contribute to the datum for B, and B does not contribute to the datum for A, except that both A and B are atomic regions in the potential scheme of spatio-temporal ex- tensiveness which is a datum for both A and B.
Hume’s polemic respecting causation is, in fact, one prolonged, convincing argument that pure presentational immediacy does not disclose any causal influence, either whereby one actual entity is constitutive of the percipient actual entity, or whereby one perceived actual entity is constitutive of another perceived actual entity. The conclusion is that, in so far as concerns their disclosure by presentational immediacy, actual entities in the con- temporary universe are causally independent of each other.
The two pure modes of perception in this way disclose a variety of loci defined by reference to the percipient occasion M. For example, there are the actual occasions of the settled world which provide the datum for M; these lie in M’s causal past. Again, there are the poten- tial occasions for which M decides its own potentialities of contribution to their data; these lie in M’s causal future. There are also those actual occasions which lie neither in M’s causal past, nor in M’s causal future. Such actual occasions are called M’s ‘contemporaries.’ These
Organisms and Environment 189
three loci are defined solely by reference to the pure mode of causal efficacy.
We now turn to the pure mode of presentational immediacy. One great difference from the previous ways of obtaining loci at once comes into view. In con- sidering the causal mode, the past and the future were defined positively, and the contemporaries of M were defined negatively as lying neither in M’s past nor in M’s future. In dealing with presentational immediacy the opposite way must be taken. For presentational immediacy gives positive information only about the immediate present as defined by itself. Presentational immediacy illustrates, by means of sensa, potential sub- divisions within a cross-section of the world, which is in this way objectified for M. This cross-section is M’s immediate present. What is in this way illustrated is the potentiality for subdivision into actual atomic occa- sions; we can also recognize potentialities for subdivision of regions whose subdivisions remain unillustrated by any contrast of sensa. There are well-known limitations to such direct perceptions of unillustrated potentiality, a perception outrunning the real illustration of division by contrasted sensa. Such limitations constitute the minima sensibilia.
Hume’s polemic respecting causation constitutes a
proof that M’s ‘immediate present’ lies within the locus
of M’s contemporaries. The presentation to M of this
locus, forming its immediate present, contributes to M’s
datum two facts about the universe: one fact is that
there is a ‘unison of becoming,’ constituting a positive
relation of all the occasions in this community to any
one of them. The members of this community share in a
common immediacy; they are in ‘unison’ as to their
becoming: that is to say, any pair of occasions in the
locus are contemporaries. The other fact is the subjec-
tive illustration of the potential extensive subdivision
with complete vagueness respecting the actual atomiza-
tion. For example, the stone, which in the immediate
190 Process and Reality
present is a group of many actual occasions, is illustrated as one grey spatial region. But, to go back to the former fact, the many actual entities of the present stone and the percipient are connected together in the ‘unison of imme- diate becoming.’ This community of concrescent occa- sions, forming M’s immediate present, thus establishes a principle of common relatedness, a principle realized as an element in M’s datum. This is the principle of mutual relatedness in the ‘unison of becoming.’ But this mutual relatedness is independent of the illustration by those sensa, through which presentational immediacy for M is effected. Also the illustration by these sensa has unequal relevance for M, throughout the locus. In its spatially remote parts it becomes vaguer and vaguer, fainter and fainter; and yet the principle of ‘unison of becoming’ still holds, in despite of the fading importance of the sensa. We thus find that the locus—namely, M’s immediate present—is determined by the condition of ‘mutual unison’ independently of variations of relevant importance in M’s illustrative sensa, and extends to their utmost bounds of faintness, and is equally determinate beyond such bounds. We thus gain the conception of a locus in which any two atomic actualities are in ‘con- crescent unison,’ and which is particularized by the fact that M belongs to it, and so do all actual occasions belong- ing to extensive regions which lie in M’s immediate present as illustrated by importantly relevant sensa. This complete region is the prolongation of M’s imme- diate present beyond M’s direct perception, the prolon- gation being effected by the principle of ‘concrescent unison.’
A complete region, satisfying the principle of ‘concres- cent unison,’ will be called a ‘duration.’ A duration is a cross-section of the universe; it is the immediate present condition of the world at some epoch, according to the old ‘classical’ theory of time—a theory never doubted until within the last few years. It will have been seen that the philosophy of organism accepts and defines this
Organisms and Environment 191
notion. Some measure of acceptance is imposed upon
metaphysics. If the notion be wholly rejected no appeal
to universal obviousness of conviction can have any
weight; since there can be no stronger instance of this
force of obviousness.
The ‘classical’ theory of time tacitly assumed that a
duration included the directly perceived immediate
present of each one of its members. The converse propo-
sition certainly follows from the account given above,
that the immediate present of each actual occasion lies
in a duration. An actual occasion will be said’* to be
‘congredient with’ or ‘stationary in’ the duration includ-
ing its directly perceived immediate present. The actual
occasion is included in its own immediate present; so
that each actual occasion through its percipience in the
pure mode of presentational immediacy—if such percipi-
ence has important relevance—defines one duration in
which it is included. The percipient occasion is
‘stationary’ in this duration.