What is the word for a person who freely uses an example, a quote, or a line of logic whenever it supports his own cause or argument, but sneezes at them if they are likely to undermine his cause or argument?
For example, person A says that four out five people do [whatever]. And whatever that is, it supports his argument. In another occasion, when he is presented with statistics he quotes Bertrand Russell's, “The fact that an opinion has been widely held is no evidence that it is not utterly absurd; indeed, in view of the silliness of the majority of mankind, a widespread belief is more likely to be foolish than sensible.”
I guess there many general words that could describe this attitude, for example hypocrisy. But I am looking for a word (or perhaps an idiom or a phrase) that specifically focuses on this type of hypocrisy.