…the philosopher Michael Huemer (Colorado) does not cover himself in glory with this sophomoric attack on Marxism.   I'll keep this brief, as I'm super busy with grading currently!

1.  Huemer says, "Without the labor theory of value, there’s no theory of surplus value, no theory of exploitation, and thus the central critique of capitalism fails."  Marx's version of the theory of exploitation has to be abandoned if one abandons the labor theory of value (as one should), but there are other theories of exploitation as a wrong available, and his "central critique of capitalism" in any case was not that it involved exploitation:  it was that at a certain point in its development, it ceases to be in the interest of the vast majority, because it harnesses enormous productive power to the production of more profit (or capital), at the expense of the well-being of the vast majority.

2.   Huemer says, "Marxism was tried many times."  It has never been tried; state ownership of the means of production has been tried in economically underdeveloped countries, with bad consequences, and I think we can agree that is a bad idea.  But that was never any part of Marx's views, indeed, was explicitly something he warned against; here's a typical remark from The German Ideology:  for communism to be possible, "[I]t [capitalism] must necessarily have…produced…a great increase in productive power, a high degree of development….[T]his development of productive forces…is an absolutely necessary practical premise because without it want is merely made general, and with destitution the struggle for necessities and all the old filthy business would necessarily be reproduced."

3.  Huemer says, "The…most obvious objection to communism is that people are not going to selflessly work for the good of society."  Marx never proposed that people should or would work "selflessly…for the good of society."  He was quite explicit that he was making no appeal to people's altruism, but to their self-interest:  it was not in the self-interest of the vast majority to continue to live under capitalist relations of production.

I think one way to avoid public displays of "irrational" beliefs is to actually know something about the subject you're discussing, in this case, Marx's views.  Professor Huemer plainly doesn't, which is why these comments fall so far below his normal argumentative standards. But they do illustrate irrationality in politics well!