Despair utilizes logos in his argument in favor of suicide in a deeply ironic scene. Redcross rushes into Despair’s cave in order to defeat the monster who has successfully convinced a number of knights to kill themselves. However, Redcross soon finds himself falling for the logical, but ultimately malevolent, argument offered by Despair, who states:
The lenger life, I wote the greater sin,
The greater sin, the greater punishment:
All those great battels, which thou boasts to win,
Through strife, and bloud-shed, and auengement,
Now praysd, hereafter deare thou shalt repent:
For life must life, and bloud must bloud repay.
Is not enough thy euill life forespent?
For he, that once hath missed the right way,
The further he doth goe, the further he doth stray.
Despair frames his argument in the manner of a logician or philosopher. The longer a person lives, he reasons, the more opportunities they have to commit sin. If “greater sin” leads to “greater punishment,” he argues, then a shorter life is more desirable than a longer one. Redcross is deeply affected by Despair’s argument that he will one day repent for the “great battels” and “bloud-shed” that characterize the life of a knight. If “bloud must bloud repay,” Despair claims, then Redcross adds to his spiritual debt with every new adventure.
Despair’s argument showcases the ways in which logos can be manipulated and misused. In some ways, his argument is logically sound, but it is nevertheless in clear violation of traditional Christian values, which strongly prohibit suicide. The great irony of the scene is that Despair is able to use Christian arguments to reach what Spenser considers to be a deeply unchristian conclusion. For Spenser, obedience to Christian principles is far more important than following human logic. Redcross, then, has made a critical error in even entering into a debate with Despair.
The monstrous demigod Mammon, who represents wealth and greed, uses logos in his debate with Guyon about the value of wealth. When Guyon insists that he isn’t interested in gaining riches as he believes that a true knight needs nothing but a sword and shield, Mammon recognizes a weak spot in his argument, stating:
Vaine glorious Elfe (said he) doest not thou weet,
That money can thy wantes at will supply?
Sheilds, steeds, and armes, & all things for thee meet
It can puruay in twinckling of an eye;
And crownes and kingdomes to thee multiply.
Do not I kings create, throw the crowne
Sometimes to him, that low in dust doth ly?
And him that raignd, into his rowme thrust downe,
And whom I lust, do heape with glory and renowne?
Though Guyon isn’t tempted by Mammon’s piles of gold, he is nevertheless unable to turn down a debate. Guyon’s characteristic desire to prove himself serves Mammon's purpose just as well, and he lays a rhetorical trap for the young knight: the equipment of a knight—“Sheilds, steeds, and armes”—are also economic goods, Mammon argues. Even a Knight, then, can make no claim to be entirely independent of the monetary system, as their “wantes” are ultimately supplied by money.
Mammon continues to adapt his tactics, pointing out that “crownes and kingdomes” are similarly founded on money, as a king who lacks money is “thrust downe” into “dust,” but a wealthy king gains “glory and renowne.” Mammon’s logic is sharp here, highlighting the naivete of Guyon’s position. As with Redcross in the cave of Despair, Guyon has erred in entering into a debate at all with a demonic figure such as Mammon.