Words and attributes
Words are classified in various ways -- nouns, adjectives, verbs, etc. In an analogous manner, semantic concepts may also be classified, but not necessarily along the same lines that the grammarians are using. Let us examine various attributes for describing a person. Some of them concern permanent physical properties: male, female, tall, short, brown-eyed, etc. Others characterise long-term behaviour patterns: keen on sports, couch potato, cinema freak, cheerful, pessimistic, etc.
However, there are also a number of transitory states that a person may be in – running, crying, happy, sad, drunk. Transitory states may also be described with semantic attributes. Note that their semantic function -- describing the transitory state of a person -- remains the same, whether they are expressed as verbs, nouns or adjectives.
Commandable and non-commandable
A useful classification of transitory states is to group them according to whether or not this particular state of the person can be changed by commands from the outside (if they are "commandable" or "non-commandable"). For example, if Tom is in the transitory state of "running", then we can make him stop by saying: "Stop running!" Tom may be stubborn and refuse, but it is still easy to see that the transitory state "running" belongs to the commandable category, because in principle a person can be commanded to run (or to stop running).
The transitory state of being "feverish" is on the other hand not commandable. No matter how persuasively I plead: "Please stop having a fever!", your fever still persists. Nor will you get a fever by my mere urging: "Now, please have a fever!" Short of medical intervention, the transitory state “feverish” is non-commandable.
Hate now, love later (or vice versa)!
"Hate" is also a transitory state. Is it a commandable or non-commandable one? It's quite clear that it is impossible to make you hate Betty by merely commanding: "Hate Betty!". Hate is an emotion that springs forth from within, involuntarily.
On the other hand, it is possible to incite hate -– there are even laws against it. But inciting hate involves a measure of deviousness and deception, in this case perhaps telling things about Betty that you are sure to hate, e.g. that Betty betrays her friends, that she uses people and that she is a member of the KKK. But even if the hateful things about Betty are true and lead you to hate Betty, then your hate is not really "your own". Rather, it’s indirectly elicited via your hate of the bad things, not of Betty herself. So hate is in principle non-commandable. In certain situations it can be incited from the outside by devious schemes, making it appear commandable. But if the schemes are exposed (by e.g. proving that Betty is actively anti-KKK, etc.), then incited hate evaporates -- easy come, easy go.
Always be polite and kind
"Politeness" and "kindness" are again transitory states that are obviously commandable. Politeness is not a physiological autonomous reaction, but a pattern of controllable behaviour (saying 'hello, nice to meet you', opening doors, helping ladies with their coats, offering seats, making light conversation). We have all been trained to follow the politeness scheme of our particular culture. If we don’t, then we are easily brought back to civilised territory by the exhortation: "Be polite!" Politeness is a commandable transitory state. Kindness, which is a generalised, more subtle and much more profound version of politeness, is also commandable, for the same reason.
Christian love
As most of us have experienced, "love" is a most enjoyable transitory state. It would be expedient to be able to start loving by commanding yourself: "Now I must love Betty". But love, like hate, is deep down an involuntary process. You can not love by command, not by your own command, nor by anybody else’s. Nor are there any useful deceptions for inciting love (except in rather far-fetched cases, e.g. when you tell a pop-crazy groupie that Bob used to be a drummer in the XYZ-band). You can of course fake or act loving, but this isn’t what we mean by the concept. Love is clearly non-commandable.
Hence the well-meaning exhortations to "love your fellow men", often heard from preachers and professional do-gooders, are useless. Or more to the point -- they are built on a misunderstanding of the meaning of the concept. You could also maintain that the exhortation "Thou shalt love thy neighbour as thyself ", which is sometimes said to be the very foundation of Christianity, is built on a mere semantic misunderstanding.
It’s no coincidence that the philosopher Immanuel Kant, himself a religious man, rephrased the main idea of Christian ethics by omitting the annoyingly misplaced word "love" -- Act only according to that maxim whereby you can at the same time will that it should become a universal law. (In a simplified version: Don't act differently from how you would like others always to act).
Reference:
Immanuel Kant: Grundlegung zur Metaphysik der Sitten (Foundations for the Metaphysics of Morals)(1785)
A HateQuest 2006 contribution