contagion1In Definition 3 of Part III of the Ethics Spinoza writes, “By emotion (affectus) I mean the modifications of the body, whereby the active power of the said body is increased or diminished, aided or constrained, and also the ideas of such modifications. N.B. If we can be the adequate cause of any of these modifications, I then call the emotion an activity, otherwise I call it a passion, or state wherein the mind is passive.” This is an extraordinary and remarkable definition of emotion, that goes well beyond associations we might have between emotions and feelings.

From the outset it can be discerned that the definition has two parts. On the one hand, affectus refers to modifications of the body. Insofar as Spinoza references the active power of the body, we should not understand feelings, but rather the capacity of the body to act and be acted upon. bats1 Thus, for example, the affects of a bat consist, on the one hand, in its capacity to encounter the world in terms of sonar, but also in its ability to fly, grasp, tear with its teeth, etc. Likewise, my fingers pounding away on this keyboard constitute an affect or capacity of my body. Or rather, my body here enters into an assemblage of affects produced through the conjunction– the “and” –of my hands and the key board, the two acting upon one another and being acted upon by one another. Through this conjugation of affects the power of bodies, according to Spinoza, is either enhanced or diminished, checked or assisted.

For this reason, Spinoza will write, in a beautiful passage, that “…nobody as yet has determined the limits of the body’s capabilities: that is, nobody as yet has learned from experience what the body can and cannot do…” (Prop 2, Scholium, Part III). It is notable that Spinoza here uses the indefinite article, indicating that bodies aren’t to be restricted to human or living bodies, but to all bodies. If, then, no one knows what a body can do, this is because the assemblages into which bodies can enter are limitless. alice_krige-borg_002 And in entering into an assemblage or a network, the body’s about of acting is increased or diminished, assisted or checked. We can thus think of a body as being akin to a field of potentials, such that in entering into an assemblage with another body, potentials of the body are drawn forth or pulled forth from the body, manifesting themselves for the very first time. Already we can sense that Spinoza’s entire theory of the emotions is contained in this conception of the body as a power of acting and being acted upon. As Spinoza will say, emotions are also composed of the ideas that accompany these affects (thoughts, feelings). Those assemblages that enhance a body’s power of acting will be accompanied by joyous ideas of these affections, while those that diminish the body’s power of acting will be accompanied by sad ideas of these affections.

In a recent National Public Radio story it was reported that ideas of affects are themselves contagious between bodies:

A new study by researchers at Harvard University and the University of California, San Diego documents how happiness spreads through social networks.

They found that when a person becomes happy, a friend living close by has a 25 percent higher chance of becoming happy themselves. A spouse experiences an 8 percent increased chance and for next-door neighbors, it’s 34 percent.

“Everyday interactions we have with other people are definitely contagious, in terms of happiness,” says Nicholas Christakis, a professor at Harvard Medical School and an author of the study.

Perhaps more surprising, Christakis says, is that the effect extends beyond the people we come into contact with. When one person becomes happy, the social network effect can spread up to 3 degrees — reaching friends of friends.

It would thus appear that emotions, far from being internal, private affairs, but are the result of collective assemblages where my own happiness is dependent on the happiness of those about me. But what, we might ask, is going on at the level of affects, what is going on at the level of bodily assemblages, to produce these ideas of affections accompany these affections?