As he began his campaign to reconsider what it means to support Israel, Peter Beinart described the problem facing the Jewish community thusly, in asking the next generation to sacrifice its liberalism on the altar of Zionism, the next generation instead is sacrificing Zionism on the altar of liberalism. This raises the question of what does Beinart mean by liberalism, and does he mean the same thing by liberalism in both parts of the proposition. As an extreme case, substituting these definitions of liberalism would convert Beinart's statement to this, the establishment is asking the next generation to sacrifice its notion that the Palestinians are humans on the altar of Zionism and instead the next generation is instead sacrificing Zionism on the altar of accepting every claim the Palestinians make in the course of their narrative.
Herein lies the crux of the Zionist-liberal, that is of the leftists who don't come out and claim to be anti-Israel, platform, they conflate recognition of the Palestinians as humans with acceptance of their narrative and the facts they cite to support it, using the same term to describe both.
Beinart probably would deny that liberalism requires accepting the Palestinian narrative without question. However, his actions demonstrate something else. Two examples demonstrate this. One is Beinart's citation for praise of the Israelis protesting the eviction of the al-Kurd and other families in Sheikh Jarrah for what Beinart calls making another plot available for Jewish settlers. Here, Beinart is clearly accepting the Palestinian narrative that the disputed properties in Sheikh Jarrah belong to the al-Kurd and other Arab families. However, this claim can be independently checked. According to Wikipedia, the issue is one of whether or not the Jewish deed from the late 19th century is valid. Further inquiry would show that since 1967, the Israeli courts recognized that the disputed properties in Sheikh Jarrah are owned by Jews, but held that the Arab residents there would be able to retain their residence by paying rent to the owner. However, in the 00's the residents received word that the Jewish ownership deeds were invalid and stopped paying rent. That led to the court case and ultimately the Israeli Supreme Court ruling that the deeds were valid. When the Supreme Court ruled on the ownership of the properties and the tenants continued to withhold rent, they were evicted.
If Beinart want to make the case that the Israeli courts erred in ruling that the Jewish deeds are valid, any facts supporting that claim would be welcome. The issue is that Beinart does not see that the Jewish deeds have to be recognized. Instead he latches onto his frame that Jews are gobbling up land and the investigation into any issue touching on the matter ends when it comes across the first fact consistent with that frame. The issue is Beinart's accepting the Palestinian narrative, and their factual claims supporting it, even when externally verifiable information can be compared against it.
A second area where Beinart accepts the Palestinian narrative irregardless of externally verifiable data concerns Susiya. The issue that Beinart raises in Susiya is that Israel refuses to give the Palestinians permits and then when the Palestinians build in Susiya without the permits that Israel withholds, Israel tears down the structures. What Beinart misses is that Susiya is in a part of Area C not far from Area A where Israel exercises no control over the Palestinians' right to build. Further, aerial photos from 15 years ago show that there was no historical community where the Palestinians are trying to build now. Instead of trying to satisfy their need for housing, which can be done within Area A, or reestablishing an historical community, which doesn't exist, the Palestinians are trying to establish facts on the ground in order to force a change in the border between Area C and Areas B/C.
By all means, we should not let our support for Israel to cause us to forget that the Palestinians are humans. This means that when there are genuine outrages committed by our side, such as "price-tag" attacks committed by Jews (that is, not actions done by the Arabs to frame the Jews), we must condemn the actions. However, we must also be vigilant in not allowing recognition of the Palestinians' humanity to be conflated with accepting every claim they make. Given their pattern of disingenuousness, both in terms of presenting details that did not happen and of obscuring details that would change a reasonable person's understanding, we should press that Palestinian allegations not be automatically accepted at face value.