Federalist 55

In general it may be remarked on this subject, that no political problem is less susceptible of a precise solution than that which relates to the number most convenient for a representative legislature; nor is there any point on which the policy of the several States is more at variance, whether we compare their legislative assemblies directly with each other, or consider the proportions which they respectively bear to the number of their constituents. . . .

Another general remark to be made is, that the ratio between the representatives and the people ought not to be the same where the latter are very numerous as where they are very few. Were the representatives in Virginia to be regulated by the standard in Rhode Island, they would, at this time, amount to between four and five hundred; and twenty or thirty years hence, to a thousand. On the other hand, the ratio of Pennsylvania, if applied to the State of Delaware, would reduce the representative assembly of the latter to seven or eight members. Nothing can be more fallacious than to found our political calculations on arithmetical principles. Sixty or seventy men may be more properly trusted with a given degree of power than six or seven. But it does not follow that six or seven hundred would be proportionably a better depositary. And if we carry on the supposition to six or seven thousand, the whole reasoning ought to be reversed. The truth is, that in all cases a certain number at least seems to be necessary to secure the benefits of free consultation and discussion, and to guard against too easy a combination for improper purposes; as, on the other hand, the number ought at most to be kept within a certain limit, in order to avoid the confusion and intemperance of a multitude. In all very numerous assemblies, of whatever character composed, passion never fails to wrest the sceptre from reason. Had every Athenian citizen been a Socrates, every Athenian assembly would still have been a mob. . . .

The true question to be decided then is, whether the smallness of the number, as a temporary regulation, be dangerous to the public liberty? Whether sixty-five members for a few years, and a hundred or two hundred for a few more, be a safe depositary for a limited and well-guarded power of legislating for the United States? I must own that I could not give a negative answer to this question, without first obliterating every impression which I have received with regard to the present genius of the people of America, the spirit which actuates the State legislatures, and the principles which are incorporated with the political character of every class of citizens I am unable to conceive that the people of America, in their present temper, or under any circumstances which can speedily happen, will choose, and every second year repeat the choice of, sixty-five or a hundred men who would be disposed to form and pursue a scheme of tyranny or treachery. . . .

Critics claim that

1: it is too small (not enough representatives) to truly represent the people;

2: representatives will not have a good understanding of the many people they represent;

3: representatives will be elected from elites, so they will not really understand or represent the people;

4: the ratio of representatives to the population will only get worse as the number of people in the country grows.

Publius acknowledges that there are many different opinions on how best to determine representation.

Publius gives examples of applying mathematical rules for representation to large and small states and why that can lead to problems.

Publius argues that there is a balance in the number of representatives: There should be enough to ensure that the views of the people are adequately represented, but not so many that discussion is not productive.

He argues that large assemblies are in danger of letting passion rather than reason guide them and cites an example from Ancient Greece of the Athenian assembly descending into mob rule.

Publius states that the House will have only sixty-five members when it starts, but over time the number of members will increase as the United States grows.

He also comments optimistically on the character and civic virtue of Americans, noting that he cannot imagine them choosing representatives that would be likely to pursue tyrannical acts or work against the common good.