Brutus objects to swearing an oath, including Cicero in the conspiracy, and killing Antony.
When all of the conspirators arrive at Brutus’s house to discuss killing Caesar, Brutus asks them to give him their hands one by one. Cassius suggests that they swear an oath, and Brutus objects.
No, not an oath: if not the face of men,
The sufferance of our souls, the time's abuse,--
If these be motives weak, break off betimes,
And every man hence to his idle bed;
So let high-sighted tyranny range on,
Till each man drop by lottery. (Act 2, Scene 1)
Brutus does not believe that they should have to swear an oath if they really believe in what they are doing. They are more likely, he feels, to betray the cause and each other if they are only loyal to the conspiracy only because they swore an oath.
Next, the men discuss whether or not Cicero should be included in the conspiracy. There seems to be some disagreement on this, because he is a man of great respect by many. Cassius is in support of including Cicero, saying “he will stand very strong with us” (2,1). However, Brutus decides that he should not be included.
Brutus’s argument is basically that since Cicero is not the head of the conspiracy, and did not start it, he will never go along with them and he won’t follow directions. He therefore does not want to risk including him at this stage in the game. Cicero is arrogant and opinionated, and even though he is well-respected by others, they cannot trust that he will follow Brutus’s lead, so Brutus does not want him.
When the men discuss who else should die, Brutus gets very preachy. He is convinced that no one else should die but Caesar. Cassius wants to kill Antony, feeling that he is dangerous, but Brutus feels that they should only kill Caesar.
Our course will seem too bloody, Caius Cassius,
To cut the head off and then hack the limbs,
Like wrath in death and envy afterwards;
For Antony is but a limb of Caesar:
Let us be sacrificers, but not butchers, Caius. (Act 2, Scene 1)
As far as Cassius is concerned, Antony is good with words and might sway the crowd. However, Brutus is concerned with public opinion and how it will look if they kill Antony too. He is very worried that they not be seen as butchers. He also seems to think that Antony is not dangerous. This, of course, is a serious miscalculation. Cassius pushes, saying that he fears Antony, but Brutus says all Antony can do is kill himself.
Not taking an oath and not including Cicero in the conspiracy are minor matters. The latter was probably a good idea. Leaving Antony free to influence the people is one of the biggest mistakes that Brutus makes. Antony is always underestimated, because he likes to party and he seems like nothing more than a solider and an oaf. However, he is actually a shrewd politician and an extraordinarily gifted public speaker. He will turn the tide of the war by convincing the crowd to support him instead of the conspirators with Caesar’s eulogy.