Requirement and Restrictions for Declaring Attackers

Question

This is a question I've had for some time. It involves rule 508.1 from the Magic: The Gathering Comprehensive rules. I feel the rules are a little ambiguous, and I wonder if someone can elucidate which of several interpretations is correct.

Consider the following situation. Entering my declare attackers step, I control a vanilla creature and an Ekundu Cyclops. Ekundu cyclops has the text

If a creature you control attacks, Ekundu Cyclops also attacks if able.

The Ekundu Cyclops is enchanted by Pacifism, which has text

Enchanted creature can't attack or block.

My question: What are the legal declarations of attackers here?

The relevant part of the rules for resolving this question seems to be

508.1c The active player checks each creature he or she controls to see whether it’s affected by any restrictions (effects that say a creature can’t attack, or that it can’t attack unless some condition is met). If any restrictions are being disobeyed, the declaration of attackers is illegal. Example: A player controls two creatures, each with a restriction that states “[This creature] can’t attack alone.” It’s legal to declare both as attackers.

508.1d The active player checks each creature he or she controls to see whether it’s affected by any requirements (effects that say a creature must attack, or that it must attack if some condition is met). If the number of requirements that are being obeyed is fewer than the maximum possible number of requirements that could be obeyed without disobeying any restrictions, the declaration of attackers is illegal. If a creature can’t attack unless a player pays a cost, that player is not required to pay that cost, even if attacking with that creature would increase the number of requirements being obeyed. Example: A player controls two creatures: one that “attacks if able” and one with no abilities. An effect states “No more than one creature can attack each turn.” The only legal attack is for just the creature that “attacks if able” to attack. It’s illegal to attack with the other creature, attack with both, or attack with neither.

First of all, it is pretty clear that in no valid declaration of attackers can the Ekundu Cyclops attack. The rules are explicit that the effect of Pacifism constitutes a "restriction" on attacking that cannot be overridden by any "requirement". Since the Cyclops' effect is phrased without the word "can't", I interpret the Cyclops' ability as a requirement under the condition that another creature is attacking.

There are a few ways to interpret the bold section, in my mind. We could interpret it to say:

If the number of requirements that are being obeyed is fewer than the maximum possible number of requirements that could be obeyed under any possible declaration of attackers without disobeying any restrictions, the declaration of attackers is illegal.

Under this interpretation, it would be illegal to attack with the vanilla creature, since if one attacks with the vanilla and not the Cyclops, then the Cyclops' requirement to attack is violated, while it would be obeyed if I had chosen not to attack with the vanilla. Under this interpretation of the rules, I also find it uncertain whether we consider the Ekundu's requirement "obeyed" if the conditional that another creature is attacking is not satisfied. Perhaps if neither creature attacks then there are no requirements obeyed. We could also say

If the number of requirements that are being obeyed is fewer than the maximum possible number of requirements that could be obeyed if this creature were to attack without disobeying any restrictions, the declaration of attackers is illegal.

In this case, we could attack with the vanilla, as attacking with that cyclops will never result in a legal attack.

Edit:

It seems pretty clear to me that people here interpret "could be obeyed" to refer to all possible configurations of attackers that do not violate restrictions. The ambiguity boils down to this: if a creature has an ability that says "This creature attacks if X" and X is not true, does that count as a satisfied requirement (since the clause in itself is true), or does it not count as a satisfied requirement (since the conditional is not met)?

Answer 1

You are allowed to attack with your vanilla creature.

The Cyclops' ability becomes an attack requirement if and only if it is able to attack:

If a creature you control attacks, Ekundu Cyclops also attacks if able.

However, Pacifism makes it unable to attack under any circumstances, so it doesn't become a requirement that you would have to satisfy. Therefore, you are free to attack with your vanilla creature. Look at the example section of 508.1d to see an example of when the rule would apply.

Answer 2

You can attack with just the vanilla creature

The section of 508.1d that you highlighted says:

If the number of requirements that are being obeyed is fewer than the maximum possible number of requirements that could be obeyed without disobeying any restrictions, the declaration of attackers is illegal.

In the scenario you describe, there are two different declarations of attackers that do not disobey any restrictions:

1. You attack with nothing. In this case, there are no requirements, so you are obeying 0 out of 0 requirements.

2. You attack with just the vanilla creature. In this case, the Cyclops has a requirement to attack, and you are not obeying it, so you are obeying 0 out of 1 requirements.

So, among the cases where the Cyclops is not required to attack, you can obey up to 0 of the 0 requirements, and among the cases where the Cyclops is required to attack, you can obey up to 0 of the 1 requirement. Therefore, both of those attack declarations obeys the maximum number of requirements, so they are both legal.

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Variant Scenario

Compare with a slightly different scenario: you control an Ekundu Cyclops and a vanilla creature, and your opponent controls a Silent Arbiter instead of a Pacifism. This situation has a different attacking restriction because Silent Arbiter has the ability

No more than one creature can attack each combat.

In this case, there are three possible declarations of attackers that do not disobey any restrictions:

1. You attack with nothing. In this case, there are no requirements, so you are obeying 0 out of 0 requirements.

2. You attack with just the vanilla creature. In this case, the Cyclops has a requirement to attack, and you are not obeying it, so you are obeying 0 out of 1 requirements.

3. You attack with just the Cyclops. In this case, the Cyclops has a requirement to attack, and you are obeying it, so you are obeying 1 out of 1 requirement.

This case is different because you can obey a maximum of 1 requirement in the cases where the Cyclops is required to attack, so you can't choose to disobey that requirement and attack with just the vanilla creature.

Answer 3

You can attack with the vanilla creature, but I have a different justification than the existing answers.

There is exactly one restriction in effect:

Ekundu Cyclops can't attack or block.

There is exactly one requirement in effect:

If a creature you control attacks, Ekundu Cyclops also attacks if able.

First, we must satisfy all restrictions. This is easy: don't attack with Ekundu Cyclops.

Next, we must satisfy as many requirements as possible. This particular requirement contains two "if" conditions, and one of them is always false.

If a creature you control attacks, Ekundu Cyclops also attacks if able.
If a creature you control attacks, Ekundu Cyclops also attacks if false.

It makes no difference whether a creature you control attacks, because the other "if" always evaluates to "false".

Answer 4

Hackworth's answer is correct and Ekundu Cyclops only has to attacks if another creature attacks and if able.
But in addition, and as general rule of thumb (since I can't find the correct number of the rule):

Effect's that say you "can't", are "prohibited", are "not allowed to" have precedence in comparing effects. So your Ekundu Cyclops HAS to attack, but it also CAN'T attack, so the effect tha says it can't do something is considered the one that counts.

Similarly if your opponent plays Silence and you have a Isochron Scepter into play. If Silence has already resolved you can't use (or rather it will have no effect) Isochron Scepter's activated ability since it makes you cast a spell (a copy is made and you can cast it) but Silence does not allow you to cast spells till end of turn.

The part you were worried was "If the number of requirements that are being obeyed is fewer than the maximum possible number of requirements that could be obeyed without disobeying any restrictions, the declaration of attackers is illegal" but since there is a restriction (something that says it can't attack) the requirement goes against a restriction and so does not have to be taken into account. That way attacking only with your vannila is perfectly legal.