§32. Nominal Knowledge

That sense perception is mediated, that intermediaries of some kind stand between the distal cause of sense and our perception, is a robust idea in European thought. From the first Greek accounts, the senses involve travel, with departure, passage, and arrival.

Emissary theories passed into medieval European thought with the Arabic sources of the new Aristotle. In the thirteenth century, Grosseteste and Bacon speak of species, one usual Latin translation of Aristotle’s eidos (form). In the fourteenth century Peter Aureoli introduces “intentional apparent beings” to mediate the cognition of natural things. In Locke, the intermediaries are explicitly described as causes, meaning efficient causes of ideas. In Descartes, physical patterns in the pineal gland are directly inspected and used to infer external things. Ockham is the first anti-emissary in the theory of know­ledge, the first “anti-representationalist.” “All the things that the philosophers and saint doctors call phantasms, effigies, and pictures are the sensible things themselves, which have first been perceived and are then imagined, not spe­cies of sensible things. It is the same man I have previously seen I now im­agine, not a species of that man.”⁶⁵

If we require an intermediary to perceive an object, then we require an intermediary to perceive the intermediary, and sensory cognition becomes unintelligible.

The difference between Ockham and the Pragmatist is that while Ockham gives up cognitive intermediaries he does not give up certainty, whereas pragmatists advocate fallibilism and knowledge without foundations. Rorty scoffs at the “myth of the given,” the infallible certainty of sense-founded knowledge. Knowledge for this pragmatist is a conventional status conferred on propositions and their speakers by their language community (§91). Ockham instead makes the given absolute. The given is not a special seg­ment of knowledge, a foundational subclass; all knowledge is immediately given or it is not knowledge at all. Ockham’s name for this given is “intuitive cognition.”

He opposes any explanation of cognition on the model of the species theory in optics, the line of research initiated by Grosseteste, advanced by Bacon, and continued in Pecham and Witelo. Their work unites geometry, psychology, and logic in a theory of what they call the multiplication of spe­cies, “multiplication” meaning generation, as in “Go forth and multiply.” The idea is that a visible object generates a species (a sensible, qualitative form) of light and color in the adjacent transparent medium.

The streaming multiplication of species is not a mechanical transmission, not like a ripple in the Stoic pneuma; it is the successive activation of a poten­tial in the medium. Bacon does not think of species on the model of atomic eidola. Species are not bodies and do not move from place to place. “There is no change of place,” he writes, “but a generation multiplied through the different parts of the medium; nor is it a body which is generated there, but a corporeal form that does not have dimensions of itself... and it is not pro­duced by a flow from the luminous body but by a drawing forth out of the potentiality of the matters of the air.” Once species have been multiplied to the internal common sense around the heart they combine into synthetic images, which are multiplied again to a second internal sense, imagination, so named for the images it stores. The multiplication process continues to the intellect, perhaps by the abstraction of an intelligible species impressed in the intellectual faculty, though Bacon's account gets thin at this point.⁶⁷

The theory troubles Ockham because it seems an open door to skepticism. What assurance have we that the senses are adequate to discern the species of things? How can we verify that the concept resulting from sensory interac­tion is trustworthy and accords with the object? This phantasm supposedly derives from the sensible species, and neither the phantasm nor the sensible species includes the object's substantial form, yet by acting on the phantasm the intellect knows that substantial form—a mystery indeed! What makes these internal psychological operations on species a reliable source of truth about nature? How do we distinguish perceiving the species from remem­bering or imagining it? What is the difference between actual perception and imagination or memory when it is the same phantasms stored in im­agination and contemplated by intellect, whether perceiving, remembering, imagining, or for that matter asleep and dreaming? No one had answers to these questions.

Bacon’s ideas on the multiplication of species were reworked at Paris in the decade after the Opus majus, and the difficulties were well exposed. Duns Scotus focused on the threat to certitude posed by species in perception. It was at this time that the distinction emerges between intuitive and abstractive cognition, often (perhaps incorrectly) attributed to Scotus. Ockham rejects the species account and develops a theory based on the new distinction. By intuitive cognition the intellect evidently cognizes a thing’s existence and im­mediately judges it to exist. Evident knowledge of a proposition means, not grounds for inference, but rather causation. “The intuitive cognition of the thing and the thing cause the judgment that the thing exists.” There is no intermediary. “Intuitive cognition can occur by means of the intellect and the thing seen, without any species.” And it is never wrong. “By nature there cannot be intuitive knowledge without the existence of a thing which is truly the efficient cause of the intuitive knowledge,” and the intuition is invariably followed by correct judgment.⁶⁸

Intuitive cognition is the foundation of experiential knowledge (experimentalis notitia) and scientific knowledge (notitia scientifica). The judgment verified by intuitive cognition is defined as notitia evidens, evi­dent knowledge, and explained as “the cognition of some true proposition (complexum), the sufficient mediate or immediate cause of which is a non­complex cognition of its terms.” Such judgments require intuitive cognition because “in this life, contingent truths concerning sensible objects can only be known when they are before the senses (sub sensu)” The correctness of intuitive cognition is built in. By definition, it is impossible for it to issue in false judgment. That was also how Stoics explain their cognitive impression (§18). If the thing is not actually present, intuition does not happen.⁶⁹

Intuition leaves a trace, which is the corresponding abstractive cognition.

Ockham rediscovers an idea from Democritus that Gassendi will carry into modern empiricism. We have no natural intuitive cognition of corporeal substances. We enjoy such cognition only of sensible qualities and the acts and passions of the soul, but not mind-independent corporeal substances. For Democritus, “We know nothing accurately in reality, but only as it changes according to the bodily condition.” In Gassendi, “One cannot pene­trate to the level of the substance or the intimate nature of things” In Ockham, “No exterior corporeal substance can be cognized by us naturally in itself”; “We have no other experience of substances than through accidents” It is impossible to tell whether substances of the same or different kinds are asso­ciated with a given mosaic of qualities.⁷⁰

He understandably disallows certainty in the Academic sense, where the truth of a proposition would be certified by an infallible sign. Ockham was familiar with Academic skepticism but thought no reasonable person should accept their standard of certainty (Buridan will make the same reply to Nicholas Autrecourt). We enjoy knowledge that is free of error and doubt due to its causal origin in intuitive cognition. Ockham makes Aristotelianism more consistently empirical than it had ever been. Singulars can be known with due certainty, phenomena of observation explained experimentally, and the necessity of natural processes formulated without compromising divine omnipotence. What is not possible is the grand promise of demonstrative scientia. Natural knowledge can only be experimental.⁷¹