Enumerated powers are clear until you get into the various interpretations put on that. Such phrases in the Constitution as 'provide the general welfare' are meant by the Founders as the welfare of all Americans generally rather than provide charity to the needy or whatever. However many Americans interpret that as providing welfare to the needy. And their definition of 'needy' can be quite ambiguous.
If you specify ALL Americans you include not only the needy but the various layers of the middle class and the 1 percenters. In other words the federal government is not authorized to provide charity or benefits to targeted groups but to provide services to all without prejudice.
A relevant copypasta from a great book in which the topic is briefly discussed...
The "General Welfare" in Relation to the Constitution
8. The Preamble of the United States Constitution specifies"the general Welfare" merely as one of the listed goals to be served by the Federal government in the exercise of the limited powers delegated to it, as enumerated in the body of that instrument. This mention of "the general Welfare" in the Preamble was intended, therefore, to serve in effect as a limit on the use of those delegated powers. The Preamble does not constitute a grant of any power whatever to the government.
The only other mention of the words "general welfare" in the Constitution is in the Taxing Clause (Article I, Section 8) which authorizes Congress to collect taxes ". . . to pay the Debts andprovide for the common Defense and general Welfare of the United States . . ." Here, too, the words "general Welfare" were designed to serve as a limitation in effect--as a limit on thepower granted under that clause. This excludes any power to tax and spend for all purposes which would not qualify as being for the "general Welfare of the United States" as a whole--for instance, it is excluded if for the benefit merely of a locality or some Individuals in the United States. The clause does not empower Congress to spend tax monies for any and every purpose it might select merely on the pretense, or even in the belief, that it is for the "general welfare." Congress possesses no"general legislative authority," as Hamilton stated in TheFederalist number 83.
Hamilton's Opinion
9. All of those who framed and ratified the Constitution were in agreement on this point of the limited and limiting meaning of the words "general Welfare" in the Taxing Clause. As Secretary of the Treasury, Hamilton contended for the first time in 1791("Opinion as to the Constitutionality of the Bank of the United States") in favor of a broader interpretation of this clause than he had formerly espoused and broader than that which Madison - with Hamilton's silent acquiescence--had presented in 1788 in The Federalist (especially number 41) as reflectingthe controlling intent of the Framing Convention, which Madison and Jefferson consistently supported. Hamilton did not claim, however, that this clause gives to the Federal government any power, through taxing-spending, so as in effect to control directly or indirectly anything or anybody, or any activities of the people or of the State governments. Despite his assertion that this clause gives Congress a separate and substantive spending power, Hamilton cautioned expressly (Report on "Manufactures," 1791) that it only authorizes taxing and spending within the limits of what would serve the "general welfare" and does not imply a power to do whatever else should appear to Congress conducive to the "general welfare"--that it does "not carry a power to do anyother thing not authorized in the Constitution, either expressly or by fair implication."
The Supreme Court's 1936 Decision Ascertaining andDefining the Original, Controlling Intent
10. As the Supreme Court decided (1936 Carter case) inascertaining and defining the original, controlling intent of the Constitution as proved by all pertinent records and confirming its prior decisions over the generations since the adoption of the Constitution, the contentions advanced from time to time that "Congress, entirely apart from those powers delegated by the Constitution, may enact laws to promote the general welfare, have never been accepted but always definitely rejected by this court." It also decided that the Framing Convention "made no grant of authority to Congress to legislate substantively for the general welfare . . . [citing 1936 Butler case] . . . and no such authority exists, save as the general welfare may be promoted by the exercise of the powers which are granted." The American people have neve ramended the Constitution so as to change the limited and limiting meaning of the words "general Welfare" in the Taxing Clause, as thus originally intended by The Framers and Adopters in 1787-1788.
The Founders' Warnings
11. As Jefferson warned many times in his writings, public and private--for instance in the Kentucky Resolution--in keeping with the traditional American philosophy, strict enforcement ofthe Constitution's limits on the Federal government's power is essential for the protection of the people's liberties. This point was stressed at great length in The Federalist (notablynumbers 17, 28, 33 and 78 by Hamilton and 44 and 46 by Madison) in reporting and explaining the intent of the Framing Convention expressed in the Constitution--as was understood and accepted by the State Ratifying Conventions. Hamilton's repeated warnings against permitting public servants to flout the people's mandate as to the limits on government's power, as specified in their basic laws (Constitutions) creating their governments, were in keeping with his words on one occasion in relation to the New York State Constitution. He stated ("Letters of Phocion," 1784) that any such defiance, by publicservants, of the Constitution would be "a treasonable usurpation upon the power and majesty of the people . . ."Washington's Farewell Address expressed the conviction of The Founders of the Republic and their fellow leaders, in keeping with history's lesson, when he warned that usurpation "is the customary weapon by which free governments are destroyed."