After some time your students will be justified in believing...

After some time your students will be justified in believing that either you do not have the intention to clean your office at all (that you have been lying, or confused as to what it is to have an intention), or that, if you do have the intention, then you are somehow irrational. If, in contrast, you had merely wished or desired to tidy up your office, then your inaction would be evidence neither of irrationality nor of dissimulation or confusion.

This is not to say that there are no constraints on what we can desire. Your desire that a fairy godmother should materialize and tidy up your office would properly be counted as a sign of irrationality, just as would the corresponding cognitive state of believing that a fairy godmother is on her way to do the job. Such constraints are, however, more stringent in the case of intentions than in the case of other mental states.

What does this tight connection between intentions and rationality tell us about normativity? We note, first, that acting goes hand in hand with the possibility of blame. Acting intendedly means acting in such a way that one is committed to acting in precisely the way one acts. If, therefore, what one does intendedly is a bad thing, then one is clearly at least not less blameworthy for doing it than if one had done it unintendedly.

This normative principle, namely that intended wrongdoing ought to be blamed more severely than unintended wrongdoing, is rooted in the intrinsic nature of the phenomenon of intending, and not related to conventional constitutive rules. The same reasoning explains why doing bad things on the basis of a commitment to those bad things is evaluated differently from doing those same bad things in the absence of such commitment.

Regardless of whatever general character traits one possesses, being committed to a bad thing makes one, ceteris paribus , no less blameworthy than if one does this bad thing without being so committed. This normative principle follows, again, from the intrinsic nature of intentions, and it is quite unlike those normative claims that follow from conventional constitutive rules.