The Intelligent Troglodyte’s Guide to Plato’s Republic, 2016a

42 Parts of the Soul -- Appetitive and Rational
See 434d-439e. They have determined to their satisfaction what it is for a city to
be just. Now they want to know if this definition can be applied to the soul. Since
their definition of justice requires that the city have parts, it cannot be applied to
the soul unless the soul also has parts. So Socrates is going to try to prove that the
soul has parts, that they are three in number, and that their work in the soul
corresponds to the work of the three parts of the city – “the rational part” of the
soul corresponding to the rulers of the city, “the appetitive part” of the soul
corresponding to the city’s laborers and craftsmen, and “the spirited part” of the
soul corresponding to the auxiliaries. The key idea in his argument is stated at
436b-c: “the same thing cannot do or undergo opposite things . . . in the same
respect, in relation to the same thing, at the same time.” He has in mind
something like this: You are overweight and your doctor has put you on a lowcalorie
diet for health reasons. One night, the waitress rolls out the dessert tray,
and you are face to face with Chocolate Sin Cake. You must have this cake. But
clearly, this would be to break your diet and take a step closer to bad health, and
you care about improving your health. You find yourself pulled in opposite
directions (to eat and not to eat) with respect to the same thing (the cake) at the
same time. Therefore, Socrates would say, your soul must have at least two
distinct sources of motivation, an “appetitive” part to desire the cake and a
“rational” part to desire health. The example Socrates gives in the present passage
is of people who are thirsty, but – for some reason left unspecified – don’t want to
drink. The concern in opposition to thirst could be any number of things: health
again (the water might be dirty), or courtesy (your friend hasn’t finished giving the
toast), or piety (the period of fasting has not ended), or group survival (you and the
others in the lifeboat are down to your last pint of water). Socrates offers this
example as proof that the soul has a rational as well as an appetitive part. How
does he understand the difference between these two parts of the soul? He tells us
that the appetitive part desires “the pleasures of food, sex, and those closely akin
to them,” and that, of the appetites, the clearest examples are hunger and thirst. It
appears then, at first glance, that the appetitive part is concerned with pains and