David Hume’s Treatise of Human Nature is a tour de force philosophically. It has been one of the most influential pieces of philosophy ever. Although incredibly influential, it is not without its problems. Hume’s theory of mind and ideas ran into various complications when confronted with the notion of abstract ideas. Hume’s response to this issue isn’t all too convincing and seems as if he knows he is wrong but bites the bullet anyway for the sake of philosophical consistency. Baruch Spinoza, in part two The Ethics, states in proposition 40: “Whatever ideas follow in the mind from ideas which are adequate in the mind are also adequate”. Hume would disagree with Spinoza twofold: (1) Hume doesn’t know where ideas come from -because they derive from simple impressions, which arise from unknown sources. (2) Hume does not think any of our ideas can be adequate. Hume, however, would partially agree with Spinoza, in regards to universal ideas and their likening to Hume’s “magical faculty of the soul”, though he cannot be in full alignment with Spinoza here, as Spinoza’s doctrine has no “custom” to get us out of the messiness of universals.
1.1.7 of the Treatise is where the complication of abstract ideas arises for Hume. This problem arises because Hume doesn’t think ideas can be universal/abstract. Hume asserts vehemently that ideas are only particular. Hume’s reason for believing that all ideas are particular, is because all of our ideas -at least simple ones- derive from impressions, which are perceptions -which is all that anything is in Hume’s philosophy- of particulars. Most people, however, do not think that we can only have particular ideas. It is conventional wisdom to assume that there are 3 kinds of ideas: (1) particular ideas (2) universal ideas (3) abstract ideas -though the latter two are difficult to distinguish. It is often, in fact that we think of things as universals (ex: Amazon sells particular books; Amazon doesn’t sell “book” (i.e. the universal).
Hume dismisses this as mere linguistic nonsense. He recognizes that we speak and think of things/ideas as if they’re universals but he rejects the idea that they actually are universals. Abstract ideas to Hume do not exist, though he realizes that it is a quite difficult notion to flat out deny when it is so commonplace to assume that abstract ideas exist. He attempts to refute abstract ideas by observing that when we attempt to express abstract ideas (ex: all apples) there isn’t any one idea of an apple that expresses the idea of all apples. None of the ideas of generality can be formed without the ideas of peculiarity according to Hume. An example would be the computer I am currently typing on: let’s say I never encountered a computer before and me using it and learning how to use is only occurring right now; without some particular impression and thus particular idea, it would be impossible for me to even begin to conceive of any abstract notion of computers plural. The mind simply does not have the prerequisite infinite capacity to abstract things with which it never had a particular impression -therefore idea- of.
Hume, although he dismisses ideas that are deemed to be abstract but which are really particular, cannot deny the fact that our discourse on ideas involves the notion of abstract ideas. This is a complication for Hume, as it is seemingly paradoxical: how could a multitude of individuals speak in terms of ideas which are in no way as they seem? Hume’s way out of this, is to conclude that abstract ideas are no doubt actually particular ideas -because all ideas are particular ideas- but when such ideas are represented though our reasoning faculties, they are discussed as if they are actually general ideas.
Hume’s cop-out of the generalization of ideas, which are no doubt actually particular ideas, is when we name something which is associated with many particular ideas. An example could be books: hearing the word “book” brings forth many particular ideas of books which are all united under the flag of the initial utterance. All such ideas have a resemblance with the basic idea of “book” and with hearing what calls forth the many resembling particular ideas, is what Hume called a “custom”. A custom to Hume is essentially the hearing of one idea, brings about many other similar ideas, and conceiving them as associated in the imagination. Ideas in nature -as they exist in the mind- are particular and only are general by custom. The effect that custom has on us, is that it provides counter examples to universals, which nullifies the entire edifice of a universal. An example of this could be: “all cats are spotted black and white” but the custom of the mind negates this universal assertion by providing counter-examples such as particular calico cats or siamese cats amongst many.
The way abstract ideas come about, is just as unsatisfying as explaining how they are simply an illusion of many similar particular ideas. Where abstract ideas are derived from -almost like simple ideas, although Hume is more bleak with regard to simple ideas- is unknown to us. Hume -who is known to have an entire doctrine dismissing the idea of miracles as being extremely unlikely- describes the phenomena of abstract ideas as deriving from “the magical faculty of the soul”, which is the imagination’s power of association of particular ideas. Hume cannot say anything about this faculty -especially considering he didn’t see the soul as a Platonic/Christian separation from physicality- other than that it is incomprehensible to us mortals. The magical faculty of the soul, entails complex ideas which are never thought of in their entirety -that is, we do not unfold all of the specific simple ideas which compose the complex idea in order to grasp it- yet are spoken about in a manner of full comprehension; A good example of this is economics or morality: there are facts to be known in these fields, many of which we do not, and many of which we do, but are often not always at the forefront of our dialogue with regard to these fields; yet, we speak in ways to avoid nonsense in these fields (example: in economics, we know that burning all of the world’s money is a bad idea) and perceive repugnance toward bad ideas in these fields (example: we do not consult Jeffrey Dahmer for moral philosophy).
Although again, it is incomprehensible to grasp where it derives, Hume provides proofs of the soul’s magical faculties’ existence -one (complex ideas spoken about in a manner of full-comprehension of all simple ideas which compose it) being displayed in the previous paragraph. The second explanation for this phenomenon is the existence of habits that are triggered by the utterance of certain words or a word. This is synonymous with the subjective component of his theory of knowledge/causation (ex: I commonly see objects A&B together; when I see object A, it causes me to perceive the idea of object B); in this case, however a single word which is a associate with a string of other words, automatically brings forth in the mind the expected continued utterance of the past experienced stringing of words (example: someone can say the beginning of the verse of a song and abruptly stop, while the continuation of the song occurs in my mind due to hearing it began though someone else’s utterance).
Baruch Spinoza in proposition 40 of the second part of The Ethics asserts that“Whatever ideas follow in the mind from ideas which are adequate in the mind are also adequate”. This is a very dense proposition which states what type of ideas are adequate and which are not. These types of ideas, in fact are the basis of our reason -which he calls “common”, according to Spinoza and that such ideas derive from God’s essence as a human mind. Schol. 1 states the idea of transcendental things, which are images that the human mind produces to with a certain limited number, which if exceeded has diminishing returns in the form of confusion in our perception of said images. Such images are of bodies, and when the images become confused from too high a quantity of them, the mind will have a confused perception -on top of the already confused individual perceptions- of the bodies and comprehend them all under one attribute -that which Spinoza called a “universal”. Universals are notions of a large quantity of images, which is so large in fact, that the particular images can no longer be distinguished from one another. The only imaginable truth to be derived from universals is what the particulars that it consists of agree in (ex: many different breeds of cats under the universal of Cat, all agree on the kingdom Animalia or genus Felis but individually differ by a significant margin). Ideas of extension and thought are also forms of universals, but they are true because they are modes of God’s attributes of thought and extension, and it is an axiom that any idea which derives from God is true.
Conceptions of universals under Spinoza are relative from person to person. Differences among different individuals on this front, derive from different minds having been affected differently -in terms of frequency of affectedness- and what the mind recollects the most easily. An example here could be the notion of human to person A could be mostly associated with rationality and person B barbarism; these are two entirely different aspects of the same thing but these associations block out all other characteristics of humans; the word human to person A dosen’t signal barbarism and the same for person B with regard to rationality. This is also definitely the case with the universal notions of thought and extension because everyone’s thoughts are not aligned and that is the same with everyone’s perception of extended things (ex: person A is thinking of God and person B is thinking of chicken (thought), while simultaneously person A see’s chicken and person B see’s a church (extension).
Hume and Spinoza are not exactly parallel on this particular front. On the one hand Hume would reject all of Spinoza’s pantheism as fantasy and thus wouldn’t accept his premise of adequate ideas deriving from God’s essence as a human mind. Hume would not reject that adequate ideas are followed by adequate ideas, by itself -that is, supposing that adequate ideas can even be had. Hume’s philosophy leaves no room for adequate ideas, because Hume doesn’t think there is anything to be learned from experience and observation. This is to the extent that Hume didn’t even think philosophy was worth pursuing. Reasoning to Hume is nothing other than another form of perception that we cannot know with rational knowledge exists outside of the field of perception -in fact, to Hume all that exists is perception and rational knowledge isn’t something that actually exists. Therefore, Hume would not have agreed with Spinoza on this account; the closest thing to an adequate idea Hume would have got behind is an idea which is stronger than a subordinate one, but this by no means includes its actual adequacy and truth value. Therefore, the title description of P40 is not something Hume could possibly agree with because he doesn’t believe adequate ideas are even possible; demonstrable reason is a fallacy and probable reason denigrates into nothing (1.4.1) -the latter of which is the basis for all of our knowledge, which in 1.4.1 has been reduced to either nothing or willful blindness of such reduction which is equated to “belief”.
With Spinoza’s account of universals, it is possible that Hume and Spinoza can find middle ground. This middleground is directly related to what Hume described as “the magical faculty of the soul”. Although Spinoza and Hume would not agree on where such a faculty derives from, they may agree on what it constitutes. What is most similar between Hume’s idea of abstract ideas and Spinoza’s account of universals, is that they both consider particular ideas to be of most importance but differently; Hume takes it to be no ideas are actually abstract, but only seem to be so when represented -i.e. All ideas are actually particular ideas- and Spinoza takes universals to be composed of too many particular ideas, which results in distorted perception of the many particular ideas.. Hume’s “magical faculty of the soul” leave out what Spinoza adds: that such complex ideas (or to Spinoza “Universals”) are distortions; Hume doesn’t make the same move as Spinoza here: all he says is that this faculty allows us to speak of complex/abstract ideas as if we fully comprehend the composition of them -which is made up of many particular ideas. Also, Spinoza dosen’t make the same move as Hume in that he assures that custom can provide counterexamples to get us out of the messiness of speaking in universals; Spinoza makes it as if the number of images that compose a universal can become so large that distortion of becomes irredeemable by any counterexamples.
Hume’s theory of abstract ideas also cannot agree with P40SH.2. Hume and Spinoza would agree on the 1st kind of knowledge being false but the succeeding two Hume wouldn’t accept as true; the 2nd kind of knowledge implies adequate ideas which Hume denies as being fully available to us and also the fact that knowledge is all a matter of probability to Hume -which ends up being scrutinized under a sceptial lense anyway-, and the idea of “common notions/common adequate ideas” which Spinoza accepts wouldn’t be adequate for Hume, insofar as he states in the objective component of his theory of knowledge/causation: that things which are consistently conjoined implies no necessary connection between them; it is a mere habit of association, which doesn’t supply adequate knowledge; the 3rd kind of knowledge is intuitive knowledge which seems to spring from nowhere -which is almost like “custom” for Hume- and produces adequate ideas, which again, Hume doesn’t think we can have with any certainty. These kinds of knowledge to Hume, would have influence on the mind but would have nothing to say -in terms of power or connection between the objects- of the objects in which these ideas are concerned. Oddly, the 2nd & 3rd kinds of knowledge are universals, so even by Spinoza they should be deemed at the very least confused.
Hume’s problem with abstract ideas is resolved by stating that all they are, are multiple particular ideas which are being represented. It is plausible to assert that our abstract ideas are actually as such and we need them to maintain sanity (picture when thinking “economics” you must also think about all of the simple ideas which compose it; what a miracle that we don’t!). Where all ideas are derived from is still today an unresolved territory for science/philosophy and Hume is right to say the source is unknown. Spinoza and Hume both have universals under a similar scope of understanding but Hume saves it by reverting to the “custom” consciousness, which unlike Spinoza’s notion of universals, has self-evident pragmatic use -even if in the end we should be skeptical of it like Hume is of all knowledge.