How does MP's seinsgeschichte tension with Heidegger bear on the 1959→1961 reversal?

The two are the same problem seen from opposite sides. In 1959 Merleau-Ponty anchors ontology in the "thick, opaque present" and refuses the Hegel/Marx/Nietzsche detour; by 1960–61 he gives a whole course on exactly that detour. The reversal is not a change of mind about the present but an internal consequence of the tension with seinsgeschichte: once MP refuses Heidegger's destinal sending, the only way to get from "our time gives the question" to anything articulable is through the historical structures in which the present has sedimented itself — i.e., through Hegel and Marx. The 1961 course is the 1959 anchor's logical consequence, not its abandonment.

The Two Positions

1959 (Course 1, "The Possibility of Philosophy," opening lines 203–210). Merleau-Ponty announces that he will not justify ontology through a history of philosophy — not through Kierkegaard, not through Marx, not through Nietzsche. That would be "negative." Instead he goes straight to the cultural symptoms of the present: atomic energy, art, literature, music, psychoanalysis. Ontology will be "anchored" in the opaque present, not in a historical arc.

1960–61 (Course 3, "Philosophy and Nonphilosophy since Hegel"). An entire course on Hegel and Marx. Heidegger was to come, but the May 4, 1961 lecture was never delivered (MP died May 3). The structural shape of the course is a long march through exactly the positions 1959 said ontology did not need.

On the surface this looks like a change of mind. But reading it alongside the buried disagreement with Heidegger over the Seinsgeschichte changes the picture.

The Buried Heidegger Disagreement

The disagreement, reconstructed on seinsgeschichte and in the Course Notes extraction: Merleau-Ponty accepts Heidegger's structural form — the history of philosophy as modalization of the ontological-difference, not as progress or decadence — while rejecting Heidegger's metaphysical grounding of that structure in the destinal "sending" (Geschick) of Being. "The question is given by our time" (Course 1, line 203) is not "the question is sent." MP wants the historicality without the destining.

Crucially, MP does not make this disagreement explicit. The structural placement of cultural symptoms at the front of Course 1 — before the Husserl/Heidegger sections — is the silent argument. The reader has to triangulate. Lefort's foreword at line 87 says so openly: "the construction of the course both reveals and obscures this distance."

Why the silence? Because making the disagreement explicit would dissolve it. This is the methodological parallel to good-ambiguity (Course 3): some claims can only be held by not formulating them into propositions, because the formulation would force a choice between options whose tension is the thing worth preserving. Explicit Heidegger-vs-Merleau-Ponty would force MP to either endorse destinality (losing his anchor in the present) or reject it (losing the structural form of Seinsgeschichte he wants to keep).

How the Tension Forces the Reversal

Here is where the two problems become one. If you refuse destinality, the question "how is the present the question?" has to be answered somehow. Three options:

Pure presentism. The present simply is the question, no detour needed. This is what 1959 tries. But it is unstable: to articulate what the present's question is, you have to describe how the present got to be the kind of present that has this question. The cultural symptoms (atomic energy, psychoanalysis, modern art) all require historical framing to register as symptoms of anything at all. Pure presentism collapses into implicit history.
Destinal history. Heidegger's solution. The present is the site at which Being has sent itself in a particular mode, and the task is to read the sending. Available, but refused — MP cannot accept the destinal metaphysics.
Historicality without destinality. The present is the thick sedimentation of historical structures that have become self-evident "nature." To anchor in the present, you have to un-sediment — which means going through Hegel (the theorist of sedimentation as Stiftung/institution), Marx (the theorist of the material sedimentation of social forms), and Heidegger (who will not arrive). The historical detour is not a departure from the present; it is the only way to make the present articulable at all.

The 1961 course is option 3. It is forced on MP by the combination of two commitments: (a) anchor ontology in the present (the 1959 refusal of destinality) and (b) refuse pure presentism because it is philosophically empty. The result is a historical detour that is motivated by the anchor in the present rather than being an abandonment of it.

Why This Is a Single Problem, Not Two

The buried Heidegger disagreement and the 1959→1961 reversal are the same tension seen from two angles:

From the Heidegger side: MP wants Seinsgeschichte's structural form without its destinal grounding. The 1959 straight-to-the-present move is the minimalist form of that: take the history-of-Being's insistence that the present is where philosophy is addressed, drop the "by Being" part. But without the "by Being," the "address" has no content. The 1961 detour supplies the content by turning to the thinkers in whose language the present has been deposited.
From the reversal side: MP's 1959 stance refuses to justify ontology historically, but does not explain how the present is articulated. The 1961 course supplies the articulation. This is not a concession to historicism; it is the recognition that the present is historical in itself, independently of whether a philosopher decides to treat it historically.

The link between the two: both are ways MP refuses to make a methodological decision that Heidegger had made. Heidegger's destinality settles the question of how the present is the question of Being. MP's refusal of destinality leaves the question open, and the 1961 course is the shape of leaving it open in a philosophically responsible way.

What This Implies for Reading MP's Late Work

The 1961 Hegel/Marx course should not be read as a turn away from the ontology of the flesh in V&I. It should be read as the historical underside of that ontology: the account of how the present becomes able to pose the question of Being that V&I interrogates in the non-historical register of perceptual experience.
The undelivered Heidegger lecture was structurally necessary — the course has a Heidegger-shaped gap in it. Whatever MP would have said would have had to manage the tension between "our time gives the question" and "Being sends the question" without collapsing either into the other.
The visible-invisible and flesh-as-element work of V&I is the other side of the same project: they articulate the present's opacity in the register of perception, while Course 3 articulates it in the register of the philosophical tradition. They are complementary, not alternative.

Caveats

This is a reconstruction rather than an MP-stated position. The extraction note and the Course 3 commentary on this is explicitly confidence: medium / epistemic_status: novel. MP did not write this argument; it is the one his moves force on a reader who notices both the Heidegger silence and the 1959→1961 shift.
An alternative reading: MP simply changed his mind. The Hegel/Marx detour was a concession to pedagogical necessity or to student demand, and should not be read as systematically motivated. This is less interesting but not refutable from the text alone.
A third alternative: MP is not refusing destinality in 1959 but postponing it. On this reading, Heidegger's full treatment (never delivered) would have endorsed a modified destinality that anchors in the present rather than in the sending. This is consistent with some 1960 working notes on "the flesh as element" but cannot be verified.