Much opposition to contemporary political conservatism involves a curious argumentative fallacy that I shall dub the Diachronic Red Herring. A liberal succumbs to this fallacy when he (i) appeals to the past accomplishments of liberalism to justify contemporary liberalism while ignoring the ways in which contemporary liberalism has come to occupy extreme positions; and (ii) criticizes contemporary conservatism by bringing up past failings of conservatives while ignoring the fact that contemporary conservatism accepts many of the advances of paleo-liberalism.
A Red Herring is a fallacy in which an irrelevant topic is presented in order to divert attention from the real issue. The real issue concerns contemporary conservatism and contemporary liberalism, what they are, and what can be said in support of them. A liberal commits the fallacy of Diachronic Red Herring when he attempt to defend contemporary liberalism by appeal to the past advances of people who identified themselves as liberals, when that is irrelevant to contemporary liberalism, while condemning contemporary conservatives on the irrelevant ground that people who identified themselves as conservatives failed in various ways.
To illustrate, consider universal suffrage and racial equality. It was not the conservatives of old who worked for these reforms, but people who identified as liberals. But we contemporary conservatives count these as genuine gains. Or do you fancy that Peggy Noonan and Bill Bennett and Dennis Prager do not? What we object to is the extremism of contemporary liberals who take sound ideas and pervert them. Giving women the vote was an entirely reasonable extension of the formal-egalitarian ideal. But granting it to felons, or illegal aliens, or children, or people who cannot prove their identity, is a perversion of the egalitarian ideal. These perversions are precisely what many contemporary liberals promote. But when conservatives rightly protest their extremism, they slanderously tax conservatives with wanting to 'turn back the clock' — to use their silly phrase — on genuine gains.
Now consider racial equality. I'm a conservative and I'm all for it. I want people to be judged "not by the color of their skin but by the content of their character," to invoke the familiar phrase of Martin Luther King, Jr. But precisely for this reason, I am opposed to that perversion of the ideal of racial equality that flies under the flag of Affirmative Action.
Many other examples could be given. It is reasonable to ban smoking in public places. But to ban in it in bars and tobacco shops is unreasonable. And so on. It is the extremism and irrationality of contemporary liberalism that turned many of us away from liberalism and drove us out of the Democrat Party. I should add that the issue is not Democrat versus Republican, but contemporary liberal versus contemporary conservative. An important distinction, which I leave you to work out for yourself.