A/N: not mine.

Overview: This "story" is going to be a series of one-shots, consisting of lectures from "Hogwarts School of Espionage". Here, Hogwarts (and Drumstang, and ...) are elite magical universities that teach skills useful for espionage and other special interest (*cough* criminal *cough*) groups.

Originally, I was trying to wrap a story around these lectures, but I got stuck on the plot, and character development, etc. Anyways, since my interest was always in the details of magic, not the story, I decided to just post the lectures. I'll use HP characters, but I don't expect to have any sort of story-line.

I will miss my idea of Longbottom being Snape's favorite student due to Neville's ability to make any potion explode.


"Good morning class. Please take your seats. I am Headmaster of this auspicious school. I suspect you all know my name, but I prefer to keep with the formalities. My name is Albus Percival Wolfric Brian Dumbledore. It is my great pleasure to teach this class. In this class we will cover a variety of topics, many of which will not be covered by another class. Any questions? No, then I shall continue.

"Today's lesson is about magical oaths. Magical oaths are used by many people to prove the truth of a statement. These oaths use one's own magic to evaluate the truth of a statement. One's magic will flare slightly at the end of making such an oath, proving a small light show.

"Unfortunately magical oaths are of dubious value. For example," Dumbledore raised his wand, "I, Albus Percival Wolfric Brian Dumbledore, swear upon my life and magic, that one plus one equals ten. So mote it be." A flash of light, typically seen with magical oaths, from the wand briefly illuminated the room.

Dumbledore then conjured himself a glass of water, and took a sip. "As you can see, I'm still alive, and am still magical. Can anyone please explain this to the class?"

Hermione answered, "I suspect you simply said the words and then wordless cast a brief spell, similar to lumos, to cause the flash of light."

She was reward with a broad smile. "Correct! Two points. Now for my next example, I will make an actual oath, although I have no way of proving it to you. You'll simply have to take my word for it." Wand raised again, "I, Albus Percival Wolfric Brian Dumbledore, swear upon my life and magic, that one plus one equals ten. So mote it be." This time he conjured a calabash pipe, and took a few a few puffs before vanishing it. "Now, who can tell me why I am still here to bore you with these trivialities?" A few chuckles.

"No guesses? Then allow me elucidate you. The magical oath is based on intention. In this particular example, my intention was to tell you that when using the binary representation of numbers, the result of one plus one is represented by the symbols typically read as "ten" by most people. Now in this example, I my intention was still a true statement. This is not a requirement. It is possible that your intention is completely opposite or unrelated to the words that you say. I shall not demonstrate this because it is more difficult and I hope that such a demonstration is not required for you to believe me. Although, I suppose I could make a magical oath stating it is possible." He laughed at his own joke.

"Now, who can tell me the relevance of having to cast a spell to prove that I still have my magic?"

Harry answered, "Because the flash of light only indicates that a magical oath has been made, but not the result of such an oath. The same light flashes if you tell the truth or if you lie."

"Correct! Two points! Now, how can you use this fact to make a magical oath that is completely false?"

Harry answered by taking his wand, and saying "I, Albus Percival Wolfric Brian Dumbledore, swear upon my life and magic, that one plus one equals eleven." The standard flash occurred, and Harry conjured his own glass of water.

"Wonderful! As shown, if you don't use your own name, the magical oath will not take, as your intention is for someone else. This fact makes it easy for people in our esteemed profession to swear any magical oaths required. The trick with these oaths is that your intention has to be conditional on the first claim of identity. Then, since that claim is false, then the magic can ignore the rest of the statement which includes your presumably false claim and the punishment.

"These types of oaths are very convenient for people in disguises, and allow them to make any oaths that they want. However, there is a danger. If you are in deep cover, you can come to adopt this additional identity. Adopting an identity can help you act the role you have chosen, but can also lead to problems where a true oath under the name of the false identity take affect.

"This also illuminates another possible way to falsify oaths. It is possible for you to start the magical oath at any point in your statement. This allows you to make an oath such as "I, Albus Percival Wolfric Brian Dumbledore, on pain of my life and magic, promise that all statements until I finish this oath are true. Bicycles are very useful for fish. So mote it be." A flash of magic. "Here, I didn't actually apply my magic until I started making my statement. Since the magical part of the oath didn't specify any punishments for making false claims, there were no effects of the oath. Properly used, this can be quite convincing if you first specify a false claim that can't be verified, and then include an easily verified claim under the true magical oath.

"There is one more way to defeat a magical oath, although I don't recommend it, as it is, shall we say, difficult. However, since it is your own magic that enforces the oath, it is possible to fight it off. As I said, I don't recommend it, but to practice this, you can make a magical oath with a harmless punishment, such as 'I swear that X is true, or my fingernails will grow two centimeters.' Please note that the heavier the punishment, the harder it is to fight off.

"Any questions yet? Yes?"

A lady, Daphne Greengrass asked, "Is there a way to verify what magical oath has been taken?"

"Ah, a very good question. There are some people, such as government officials and Lady Greengrass here, who are untrusting. They don't believe the evidence in-front of their eyes. And well they shouldn't. To answer your question, yes and no. There is a type of magical object called an "oath-orb" that can detect when a magical oath is made in its vicinity. I believe the more expensive models light-up while the oath is being made, rendering the partial-oath method ineffective. I believe there are also several spells which perform the same task.

"The good news is that these methods are not able to verify exactly what the oath was, so oaths made with intentions other than the spoken word will not be caught. Nor will be oaths that are made with a false identity. The bad news is that just because I am unaware of magical means to verify the details of a magical oath doesn't mean that such methods don't exist. I believe that my personal motto applies here: my ignorance doesn't make it impossible.

"Are there any more questions? No? Good. If you think of any later, please feel free to meet me later and I will attempt to address them.

"There are two further weaknesses of magical oaths. The first weakness is that of memory. For example, you could commit a crime, and have the memory removed, either willingly into a pensive, or via an obliviate spell. Once your memory of the event is gone, you can make an oath, or for that matter, testify under veritasium, that you did not commit that crime. You can even have the memory restored later, and suffer no ill from the oath. This is because the oath is only checked at the time that the oath is made. I should warn you that memory charms that hide memories may or may not be sufficient to circumvent an oath in this manner. It depends on both the spell, the skill of the caster, and the memories involved.

"The second weakness is related. You can make any forward looking statements,
that you wish. You can make a true magic oath with appropriate intent, once the oath is finished, you may change your intent freely. A word of warning: you may run into problems if, while making the oath, you intend to change your intent. That is, your oath at the time has to be genuine.

"Well, I believe that is enough of my rambling for now. I'll be available for the next hour if you have any questions. Class dismissed."

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A/N: the oblivate idea came from LessWrong's HP Methods of Rationality.