I recently became aware that there is a new development in emotion classification. Previously, as far as I knew, emotions were thought to be human universals, give or take some variation (such as the emotion “metagu” among the Ifaluk islanders, see Linquist 2007) and researchers like Paul Ekman, who works as a human ethologist of the emotions, has devised a scheme in which there are six “basic” emotions: anger, disgust, fear, happiness, sadness, and surprise. Evolutionary psychologists like Cosmides and Tooby have extended this further, arguing that guilt, fear, jealousy, etc., are adaptive responses that increase fitness in our ancestral state.
Recently, though, there has been a move to classify emotions in a more simplified manner: by valence and arousal (Russell 1980). Basically these are independent variables: a response can be positive or negative valence, and weak or strong arousal. So you end up with a 2-dimensional scheme (sometimes offered as a polar plot, but topologically it’s the same thing). A revised version of this adds a dimension for dominance (one emotion may override another), but according to the Wikipedia article, dominance is not required or supported by later research. A version of the 2D model is a 3D map of emotions in terms of neurotransmitter levels, called the Lövheim cube of emotion, but this doesn’t map onto the valency aspect cleanly.
Whatever the final account is, it is worth noting that this makes emotions grade into each other. They are not distinct and unique qualitative features of the human psyche. Fear and frustration are just coordinate locations in that space. Ekman’s universals may or may not be so universal.
One “universal” emotion that is missing from these taxonomies is love, and yet love is widely and consistently regarded as a basic human emotion in popular and philosophical discussions. Often in psychology it seems this is tied to sexual desire or attraction, and yet the philosophical tradition, going back to at least Aristotle if not earlier, distinguishes various kinds of love: erotic, personal, and fondness (eros, agapê, and philia). But if the 2D model is correct, then love is not a basic emotion, arousal and valence are, and what we call “love” is basically just a social name for a variety of states.
This is not my field so I am probably going to miss or mess up something here, but I’d like to make a couple of suggestions. First of all, sex and love are in my mind quite distinct. One is about bodily pleasure and social grooming (yes, just like bonobos, but also like most other apes if not all of them). The other is about a positive regard for another person. I think the distinctions made in the philosophical and theological literature are based on social functional categories that tie sex and love in one case (eros), supposedly unconditional positive regard in another (agapê, a Christian theological term), and personal pleasure from others in the third (philia). If sex and the value we take from others is separate from the positive regard we have for others, then to my mind, there’s just love. Love for partners, family members (particularly children), and friends is all of a muchness, and the differences are just socially constructed.
What is the practical implication of this, if correct? Well, it means one ought not to expect there is some magic threshold of positive regard beyond which one can say one is “in love”, or has found “true love” (perhaps Miracle Max had it right, and true love is a bluff), there is just love. So one might say one loves a lover, a friend or a child in the same way. However, the social context will differ, and, for example, sex will be something one engages in with socially appropriate individuals (with or without love being a part of that engagement), while one will expect a strong degree of love for children and partners that is not expected from friends (although it need not be absent in that case either) because that is the social norm for friendship.
The emotional constitution of human beings is, like everything else, an evolved derivation of biological aspects of our shared groups (apes, primates, mammals, vertebrates, etc.), and the 2D account (and if successful the Lövheim cube also) classifies these aspects of our engagement with the external world. These need not be adaptive, contrary to the evolutionary psychological approach. They merely need to be outputs of our shared and derived psychological mechanisms. What is adaptive here might be the socially constructed functional categories that play a role in folk psychology: honour and shame, for example, would be adaptations to the sociocultural environment, not the ecological environment, and be transmitted socially rather than biologically (as Linquist argues in the citation above). This is a “dual inheritance” model of emotions, although I think there is no clear boundary between biological and social evolution.
We are at the point in our researches where the neurological aspects of psychology and the behavioural and socially functional aspects are joining up, slowly. The ethical implications, however, seem not to be considered as much as I expected they would be. If love is just a second order outcome of these biological aspects of humans (or turn out to be physically interpretable, although a simple focus on neurotransmitters is obviously going to be insufficient to biologise emotions), then we can think of these categories of emotion, like honour, shame, love, disgust, etc., as things that can be modulated or even abandoned when they are no longer socially adaptive. We can now say, I believe, that we love our same-sex friends without it having any sexual connotation at all. We can choose to have relationships that are of varying strength of commitment without needing to meet the expectations of popular psychology or sociology. We might even be able to adopt a plural relationship of sexual partners or a mix of sexual and nonsexual partners in life without prejudicing those relationships by constructed categories derived from past institutions like marriage that rely upon the ideologies of class, religion or economics.