I find the word 'spitballing' very interesting. I am curious to know how this word originated. What is the logic behind the use of this word to mean "tossing around ideas?"
Oxford English Dictionary provides a citation that seems to imply that the term originated in the film industry.
I'm just thinking out loud… Spitballing we call it in the movie business.
- Harry Kurnitz · Invasion of privacy · 1956.
Prior to that meaning, spitball could mean either a spittle-ball thrown as a projectile by a schoolchild or an illegal baseball pitch altered by using spit or some other sticky substance.
Google suggested that the word came to be about in 1950.
I can't find a reputable source on its origin, nor can I find corroborating evidence for or against a film industry connection.
Best Answer
Early Spitballs
The 'spit ball' (open compound) appears as early as 1794. At that time, the reference was to an object I surmise, on the shaky basis of slightly later evidence, was used as an aid in blackening shoes:
The slightly later evidence basing my surmise was this from the Hartford Courant of 13 Jul 1801 (paywalled):
The foregoing attestations are of tangential interest here primarily because the object described as a 'spit ball' is not mentioned in other reference works. Also, the late 18th century attestation is much earlier than the 'spitball' (frequently a closed or hyphenated compound) defined in OED as a "spittle-ball [ball of chewed paper wet with saliva], esp. one thrown as a missile by a schoolchild".
This first sense of 'spit ball' appears nowhere except in the Hartford Courant, and there doesn't recur after 1802.
The OED's first attestation of the "missile" sense from Knickerbocker, vol. 27, 1846, can be antedated 7 years to 1839:
26 Nov 2020 Addition 1: Thanks to DavePhD (a comment on this answer), I can cite an earlier antedating to the journal entry of 16 Nov 1837 from Journals and miscellaneous notebooks of Ralph Waldo Emerson: Volume V 1835 – 1838 (1965, Merton M. Sealts, Jr., ed.):
Wet Ball Baseball
A sense of 'spitball' from the enormously popular North American sport, baseball, was common in the early 1900s and continues to be widely used:
US newspapers adopted the term in this sense from its use by baseball players, and have employed it frequently since at least 1903, at which time it prevailed against a competing term, 'wet ball', in use since before 1876:
Going head to head against the colorful 'spitball', that "first engine of war", it was inevitable that the bland, flavorless competitor 'wet ball' would fail.
Miscellaneous Uses
In the years between the appearance of 'spitball' in the "missile" sense sometime prior to 1839, and its later use in the "wet ball" baseball sense, a number of semi-literal and figurative uses began to appear. Many of these refer to political and legal 'mud-slinging'. Such uses continue to this day. Here are some early examples from the popular press:
Such uses are simple metaphors leveraging the "missile" sense. 'Spitball' signifies anything petty and offensive 'thrown' or 'blown', in some sense, at others.
Later Senses
Along with continued metaphorical use in the sense of "an insult, off-color remark; verbal abuse", 'spitball' enjoyed brief, localized slang use designating a particular type of "hand grenade", as recorded by Farrow in A Dictionary of Military Terms, 1918:
By 1925, the specialized sense designating a particular type of hand grenade was recorded as a general reference to "hand grenade":
It can safely be assumed that other localized and specialized senses of 'spitball' have been used, however restricted or brief such uses have been. By their very nature, spitballs paper the US cultural walls.
The Derivative Verbs
Most of the senses of 'spitball' given in the foregoing account enjoyed use as verbs. The exception is the very early, 18th century, sense of "an object employed as an aid in blackening shoes". Otherwise, for example, and without belaboring the point, 'spitballing' described the action of hurling paper missiles, throwing a wet baseball, and so on.
However, one later sense of 'spitballing', the sense of "to throw out suggestions for discussion" (OED), seems to have developed without much (if any) precursor figurative use of 'spitball' in the more neutral, general sense of "idea, suggestion, topic". The use as a verb certainly derives from earlier use of 'spitball' and 'spitballing' with reference to saliva-soaked paper missiles, then wet baseballs, but in this use the sense of "missile" has weakened to include anything being 'tossed around', speaking figuratively.
Were it not for a couple of early contradictory attestations, the later, weakened and derivative verbal use of 'spitballing' (and 'spitballed') in the general sense of "bringing up ideas and topics for discussion" would seem to have originated from repeated use of 'spitballing' in the 'trademark phrase' of a particular syndicated columnist. That columnist, Jack Crosby, a music, radio, television, drama, theater, movie et al. critic, used this 'trademark phrase' in widely reprinted columns at least once a year between 1950 (the earliest use I could find of 'spitballing' in this derivative sense) and the 1960s. His phrase took the form of direct address to a perhaps imaginary friend named "Mannie". Examples include these:
The drumbeat of Crosby's trademark phrase in his columns, and its near-singularity in the sense ("tossing out ideas") continues into the 1960s. Were it not for William Morris's thoughtful intervention (as follows) with other information in 1953 and 1954, Crosby's phrase might be taken as the original use of this derivative verbal sense.
From these instances, it is apparent that a very well-informed and expert observer of English usage, William Morris, attributes the use of 'spitballing', when it means verbal "improvising" (closely akin to OED sense 2, "throwing out topics for discussion"), to use in advertising jargon.
26 Nov 2020 Addition 2: Thanks to a suggestion by D Krueger (in a comment on this answer) and temporary access to The New Yorker archives (paywalled), I was able to locate an early use of 'spitballing', in the sense of "throwing out ideas", in a story by S.J. Perelman published 16 Jan 1937:
This use, the earliest in the sense of "throwing out ideas" that I've found, is given in a context of Hollywood movie-making story pitches, and so suggests that origin of the sense, rather than advertising jargon. Still, my reasoning in 2017 regarding development of the sense from the baseball sense of spitball pitch to an advertising pitch transfers readily to development from the baseball pitch to the Hollywood story pitch.
The Pitch
As mentioned under the previous heading, The Derivative Verbs, 'spitballing' in the sense used in advertising jargon, 'to improvise; to conceive, propose and discuss ideas or topics', seems to have developed without the precursor use of 'spitball' as a noun in the sense of 'idea, topic'. While my not having found use in that sense may simply represent a gap in the evidence examined by me, and the noun may in fact have been so used, an alternate development route seems likely.
The likely route for development of the derivative verb 'spitballing' in advertising jargon, without precursor use of the noun 'spitball' in the sense of 'idea, topic', is logically straightforward via the 'pitch'.
The verb 'to pitch' has this sense when applied to advertisement:
The corresponding noun sense of 'pitch' is this:
Although I have no 'smoking gun' of evidence establishing a connection between 'pitching' advertisements and 'spitballing' (that is, 'improvising and proposing') ideas for advertisements, the parallelism of pitching spitballs in baseball and 'spitballing' as a type of advertising 'pitch' recommends itself. Additionally, terminological chronology does not contradict adoption in advertising from use in baseball; 'pitch' is used to describe the process of selling in advertising as early as 1882:
Even supposing that 1882 collocation is not a pun leveraging both the "comparative degree" and the "persuasive speech" senses of 'pitch' as a noun, and the intended meaning of 'pitch' as used is only "comparative degree", the meaning of a subsequent collocation in 1899 also suggests the "persuasive speech" sense of 'pitch':
To provide a logical source as suggested, however, the baseball sense of 'spitball pitch' and 'spitballing' would need to have preceded the adoption of 'spitballing' in advertising jargon to describe a type of advertising pitch. As nearly as I can determine, use of 'spitball' to name a type of baseball pitch sometime before 1903 (see above), and use of 'spitballing' in 1906 (see below) to describe the action of spitball pitches, does precede the adoption of 'spitballing' in advertising jargon sometime before 1950.