What Derrida or anybody else thinks about Heidegger's use of 'Geist' and its various inflections in the Rectoral Address [English 'ghost' in the sense of a 'spirit' from Old English 'gäst' from West Germanic] most certainly provide valuable insights into the import of what the man was trying to say, or trying to avoid saying, or was deliberately intending to be left as ambiguous.

                       Compare the use of  "spirit, soul, geist and seele in the Bible:

The reason why a philosopher of all people would wish to deal in ambiguity rather than clarity is for you to judge. Some put it down to playfulness whilst I put it down to conceit in the Elizabethan meaning of the word. Apart from this possibility of a questioning of the Geist word and its several modulations this is a remarkably clear piece of writing by Heideggerian standards, and his political message comes across loud and clear.
No doubt these meanings and the connections that can be back-traced to his philosophy will be explored further, but for my part I detect nuances of individual and national assertiveness wrapped up in the Geist word itself, like my old sports teacher used to shout: 'Put some SPIRIT into it boy!' in the sense of 'effort' - 'desire to achieve' - 'to succeed.' This would gel with Heidegger's Will to Power beliefs and The Self-Assertion of the German University is obviously for Heidegger an important aspect of the greater world of The Self-Assertion of the German Folk [under the leadership..., etc.] which lies outside the ivy-covered walls of old Freiburg university with the flag-waving and marching
Ubermenchen.

The oldest trick of the trade for politicians is to speak in vague generalisations and abstractions whereby it is difficult to pin down exactly what they mean. An amusing, penetrating and ultimately painful interview by this morning's Today Programme on BBC Radio provides an example of this sort of thing. The presenter had the Shadow Chancellor back-pedalling like a trick-cyclist during a questioning of his Tory leader's promise to cut taxes. It was most illuminating in this direction.

A unique feature of Heidegger's style as a philosopher is that he carried over these political ploys into his philosophy - his works are peppered with Adolphisms and key words with a special esoteric significance for National Socialists. Stuart Elden  in his brilliant, well researched, clearly written, and highly readable:Taking the Measure of The Beiträge which is a must on any Heideggerian or anti-Heideggerian's bookshelf, mentions Klemperer's words,

'Nazism permeated the flesh and blood of the people through single words, idioms and sentence structures which were imposed on then in a million repetitions and taken on board mechanically and unconsciously... Words can be like tiny doses of arsenic.'

[See bottom of page for details of how to obtain Dr Elden's excellent article].

This is born out with the proliferation of these words [sure to ring bells with readers who were members of the Nazi cognoscenti] throughout Heidegger's writings ['grasp' appears 29 times in Basic Concepts for example.] I plan to carry out a concordance analysis of these Nazi trigger-words] at some time in the future.

His philosophy, which other than for it's fantastical Munchausenesque balloon-riding ontological adventures is dedicated to a reconciliation and identification of the Geist of the Greek hegemony and the nineteen-thirties Zeitgeist of the contemporary National Social State. The 'incipience' from which flowed and which simultaneously gave birth to the 'the Greek Ideal' and its historic benison for the West became in Heidegger's mind the model for a German-led Weltanschauung linked to the burgeoning German Nationalism or 'Racial Capitalism' of his time, which was itself fuelled by economic chaos, resentment of the German defeat in WW1 and the suffering from reparational forfeits imposed by the imprudent victors, and the jealousy of those elements of society, who could be readily recognised by their 'differentness,' and who appeared to be successful, i.e., the Jews, or those elements deemed to be a wasteful tiresome burden i.e., the Gypsies and mental defectives.

My own cognitive modus operandi however is to think things through for myself first hermeneutically, and then check out what these well known thinkers like Derrida had to say on the matter, and see if there is a meeting of minds or not. This for me is more in the spirit of inquisitive and responsible individualism, or even my own form of nominalist 'Being-Free' Daseinless existentialism, which is based upon my long life of experiential, street-wise, direct observation, that as a general rule 'the experts' and the 'professionals' cannot always be trusted, and are as imperfect as anything else in this world. The lack of trust I have for politicians, lawyers, estate agents, boxing impresarios, would-be Nigerian cyber-business associates and second-hand car salesman, [and having been the latter so I know firsthand] also extends to philosophers, who as far as I am concerned are flesh and blood creatures like the rest of us, and as such are prone to the same appetites, political agendas, interest or laziness, motivation and professional rigour or lack of it, and above all word-twisting to suit their own purposes.

The latter is a particular problem in Heidegger, where the language is deliberately capricious, equivocal, guarded and obfuscate. With Heidegger one cannot rely upon either everyday meanings and understandings, or even, the traditional philosophical tradition's semantical understandings, but to put this down to 'playfulness' rather than calculated peasant guile, particularly in view of his known record of deceit is naive in the extreme. 'Playfulness' was certainly NOT one of Heidegger's personal allurements.

The bottom line? I for one would appreciate those interested carrying out their own assessment of Heidegger's employment of the Geist-factor in the Rectoral Address based on a close reading of the text. If you haven't sufficient German to judge it in the original, it is still possible to read it completely through in English and extract the thrust of what he is saying from the overall call to his students and staff to man the spiritual barricades. A reading in English in a good translation is a method of arriving at a considered opinion, also it is a fact that most translations of his works are carried out by those interested in Heidegger and more than often sympathetic to his views as to whether 'spirit or spiritual' is implied in this exhortative address or his meaning 'mental/intellectual in his inflectional usage of the Geist-word such as geistegen Fuhrung [rendered by the translator as: 'spiritually and intellectually] and geschichtlichen geistegen Aufrag [rendered by the translator as: 'historical spiritual mission' and geistig-geschichlichen [rendered by the translator as; 'spiritual-historical' and die geistige Welt [rendered by the translator as: 'spiritual world' and geistig-volkichen Daseins [rendered by the translator as: 'our spiritual existence as a Folk.'

Now I just cannot see the point in interpreting these terms as meaning: 'mentally' and 'intellectually,' or 'historical mental mission,' or 'mental world' or 'our mental existence as a Folk etc.,' when clearly the whole volition of the piece deals with a call for the spiritual awakening of the German Folk, and in particular the youth, and not a mental or intellectual awakening which clearly they had achieved, [to a limited extent I agree] already, and demonstrated by passing the academic examinations necessary for admittance to the university in the first place.

This speech then in my opinion was mainly not a call to think and act mentally, or even intellectually, but to enter into and lend knowledgeable support to what Heidegger felt was the realm of a mass spiritual awakening of the German people guided by the National Socialist Party under the leadership of Adolph Hitler. This was about soul not sense.

References:
Taking the Measure of The Beiträge
By Dr. Stuart Elden. (University of Durham.)
European Journal of Political Theory,
©Sage Publications Ltd,
London, Thousand Oaks and New Dehi.
ISSN 1474 -8851.  2(1) 35-36;029278