My book review is below.

Shroom: A Cultural History of the Magic Mushroom by Andy Letcher
http://amazon.co.uk/o/asin/0571227708 -- June 15, 2006
http://amazon.com/o/asin/0060828285 -- February 27, 2007

4 stars out of 5

Partial critical engagement with entheogen theory of religious origins

Shroom covers topics including refutation of the mushroom theory of
the origin of religion, the recent U.K. psilocybin mushroom scene, a
critical treatment of Wasson's research methodology and mushroom
theory of Vedic religion, and Tim Leary as backdrop leading up to the
later popular use of psilocybin mushrooms. This is a valuable book
that contributes some new perspectives and new coverage of entheogens
in Western culture; this book is a must-have for entheogen
researchers. The present review focuses exclusively on his critique
of the mushroom theory of religious origins, which he sometimes treats
as though it is a critical refutation of the overall entheogen theory
of religion.

Letcher has not disproved the entheogen theory of religion, or even
fully engaged with that hypothesis. At most, he has made a partial
effort to call into question the mushroom theory of the pre-historical
origin of religion, in the form of a secret cult spreading from a
single origin over time and across regions. Letcher often comes
across triumphally as having disproved the entheogen theory of the
origin of religion, but a careful reading of his treatment of that
particular topic shows that he has actually only shown something far
narrower ; he has only refuted a highly specific point.

At most, Letcher's treatment of the entheogen theory of religious
origins shows that we have no compelling archaeological evidence for a
prehistorical mushroom cult that was secret and unbroken. When his
rhetorical verbiage and his general discussions of history are put
aside, the substance of his argumentation that remains does not amount
to a compelling argument against the frequent use of mushrooms (or
other visionary plants) throughout religious history.

Letcher's writing style is rhetorical, so that he tells the story of
recent mushroom scholarship and culture well, presenting much of
interest to the audience, including valuable new material. He uses a
biased rhetorical style; for example, "lunatic fringe", "conspiracy
theories", "unfounded speculations", "the myth" of the entheogen
origin of religion. This charged rhetorical style obscures that fact
that his argument for his refutation of the entheogen theory of the
origin of religion rests on only a few, fleetingly discussed points of
argument.

Letcher does not engage the bulk of the literary and artistic evidence
that provide sufficient grounds to support the general entheogen
theory of religious origins. He merely puts forth brief and rather
arbitrary arguments dismissing a couple of the many depictions of
mushrooms in Christian art.

Letcher's inadequate selection of cases to refute, and his brief,
perfunctory treatment of these cases, is not sufficient in breadth or
depth to compell adherents of various variants of the entheogen theory
of the origins of religion to change their position, no matter how
many times or how confidently he rhetorically dubs the theory as a
"myth". For example, he would need to engage the range of art that is
presented in the first three issues of Entheos magazine, and the range
of arguments such as those presented in Giorgio Samorini's articles
about Christian mushroom trees.

It's admirable to see an independent critical thinker comment on
selected aspects of Allegro and Wasson, but only a few of those
comments actually amount to engaging with the evidence for the general
entheogen theory of the origin of religion. Letcher makes the risky
move of overextending his specific focus on psychoactive mushrooms, at
the expense of being under-informed on the general entheogen theory
and the full range of arguments, interpretive frameworks, systems of
assumptions, and evidence of various types in support of that
broad-ranging theory.

As a thought-experiment with the hypothesis that normalized religious
cultic use of mushrooms is only a few decades old, this aspect of the
book is a valuable contribution to the field; however, Letcher
switches inconsistently between that bold but narrow hypothesis and a
broader, firm conclusion that the entheogen theory of religion
altogether is merely a recent fabrication of popular scholarship and
merely wishful thinking.

Letcher leaps from what he narrowly demonstrates, to a stance and a
claim to have shown convincingly that the entheogen theory of
religious origins (and fairly frequent entheogen use throughout
religious history) is nothing but recent wishful thinking, a
fabrication by a group that is a historical novelty: late 20th Century
psychedelics enthusiasts, including mushroom enthusiasts in the U.K.
from 1976-2006.

All theories involve a framework of assumptions. The fact that a
scholarly theory uses a set of unproved assumptions does not instantly
do away with (or "demolish") the theory. Letcher handles the evidence
by the common strategy of dividing, isolating, and diminishing each
piece of evidence in isolation, operating under the arbitrary silent
assumption that entheogen use was rare, secretive ("conspiracy"), and
deviant. But such a methodology is problematic and is controverted
by the maximal entheogen theory of religion, which holds that Western
history and Western culture have always been inspired to some extent
by the ongoing practice of using visionary plants. The unavoidable
question remains, "How are we to judge what is plausible and what was
normal for that culture?"

Should we assume that the use of visionary plants was normal and
significantly present throughout mainstream religion and culture, or
that it was rare, a secretive conspiracy, and deviant (exceptional)?
Selecting our assumptions about the backdrop, of what was normal in a
culture, affects the validity of completely isolating each piece of
potential evidence and then attempting to judge the plausibility of
reading that piece of evidence as supporting the entheogen theory of
religion. What seems plausible to a critical scholar depends on the
backdrop of what we assume was normal in the culture.

For example, Letcher affirms that the cathedral door at Hildesheim,
Germany depicts the tree of knowledge in the shape that "looks
extremely like a giant Liberty Cap", but he argues that it cannot have
meant a Liberty Cap, because the doors were carefully designed and the
depiction cannot have been secret in that case, so the image cannot
represent anything other than, or in addition to, a "stylized fig
tree".

It doesn't occur to Letcher to imagine and address the obvious
critical arguments and questions against his hasty discussion, such
as: why assume that a mushroom allusion had to be secret? why is an
officially designed depiction of a mushroom automatically ruled out as
unthinkable? why was the fig tree stylized in the specific form of a
Liberty Cap mushroom? what about the hundreds of other specifically
psilocybin mushroom-shaped trees in Christian art?

Letcher has much homework to do if he wants to try to retain his
hypothesis that psychoactive mushrooms were absent from Western
religious history until the late 20th Century, and if he intends to
convince critical entheogen scholars of that hypothesis -- a
hypothesis that will be hard to maintain after seriously addressing,
with responses to at least the most obvious counter-criticisms, the
current full range of artistic evidence (post-Wasson and
post-Allegro), which Letcher has barely engaged.