Why do so many people speak 'to' topics rather than 'on' or 'about' them? Is this a recent phenomenon? [closed]

Question

"I will speak to that later." It seems to be most common in lecture theatres. Surely the preposition 'to' can only accurately refer to the hearer in this context. The topic itself is not the recipient. One may speak 'about' a topic or 'on the subject of' something or even 'around' it. They may 'touch upon' it but not speak 'to' it. Unless they are 'referring' to it... Have I answered my own question? Can speak replace 'refer'? One may refer people to topics. Can one say, 'I will speak to you to that later?' Can one speak people to a subject? I don't think so.

I really think there are so many other options that 'to' should not be one. When someone says, 'I will speak to that', I feel that it makes the listener rather unnecessary.

Answer 1

The Oxford English Dictionary has references to such a sense of the phrasal verb to speak to going back as far as 1610. It is listed as sense 5.

5. To treat of or deal with, to discuss or comment on, (a subject) in speech or writing.

1610 J. Dove Advt. Seminaries 42, I desire them therefore..to speake to these foure points.

1637 P. Heylyn Briefe Answer Burton 78 For your charges,..I meane to take them..in order, and speake as briefely to them, as you would desire.

1662 E. Stillingfleet Origines Sacræ ii. vi. §4 Though it be a subject little spoken to either by Jewish or Christian Writers.

1706 G. Stanhope Paraphr. Epist. & Gospels III. 555 Part of this Scripture hath already been spoken to.

1735 Swift Let. to Middleton in Wks. IV. 186 A Lawyer who speaks to a Cause, when the Matter hath been almost exhausted by those who spoke before.

1778 Earl of Malmesbury Diaries & Corr. I. 166 Unprepared as he was for such a proposition, he could not, he said, off-hand, speak to it accurately.

1869 Daily News 28 Apr. The report..was spoken to by the Most Rev. Chairman..and the Bishop of Derry.

1880 Daily News 19 Mar. 2/3, I wish to call your attention..to..that allegation, and I shall endeavour to speak to it.

Answer 2

I think it refers to the idiomatic usage of speak to:

To address some topic:

• The mayor spoke to the issue of tax increases.

(The American Heritage® Dictionary of Phrasal Verbs)

also, speak to something:

[for something] to address, indicate, or signal something.

• This event speaks to the need for good communication.

• Your present state of employment speaks to your need for a better education.

(McGraw-Hill Dictionary of American Idioms and Phrasal Verbs)

Thus usage is not very recent, Ngram shows usage of "speak to that issue" at least from the '60s but the expression is older than that.

Answer 3

Speak to from Grammarist

The phrasal verb speak to is widely used idiomatically to convey various senses, including show, demonstrate, express, relate to, address, or speak about. For example, one might say that this post speaks to the meaning of speak to, or that the existence of this idiom speaks to a gap in the language, or that these examples speak to how the phrase is commonly used. The phrase could usually give way to a one-word synonym, but people seem to like using it, especially in speech.

Because the phrase speak to is also widely used in other ways, tracing the exact origin of the newer use is difficult without exhaustive research. For what it’s worth, however, historical Google News and Google Books searches limited to pre-1990 texts uncover no instances (or very few, as we might be overlooking some) of speak to used this way, whereas a substantial number of examples are to be found from the middle 1990s. By the early 2000s, the idiom is ubiquitous.

Examples

Why the Duma would give pause on a bill that is supported by more than three-quarters of the population according to some polls … speaks to the delicacy of the gay rights issue in Russia.
[Financial Times]

It is an authentic strategic governance action that speaks to the essentials of the board’s role and responsibilities.
[Good Governance for Nonprofits, Fredric L. Laughlin and Robert C. Andringa]

But the use of Geronimo’s name speaks to the powerful, if unexamined, hold that the nation’s “Indian wars” continue to have on our popular consciousness.
[Los Angeles Times]

It seems important to speak to that struggle, the struggle for meaning and > truth in life.
[Discovering Darkness in the Light, Dana DeSimon]

The talent and enthusiasm on display in this competition speaks to the country’s enormous human capital.
[Wall Street Journal]

However, as posters in comments have pointed out, the phrase has long been in use. For example, from The Parliamentary History of England, from the Earliest Period to the Year ... By William Cobbett:

Before 1 speak to the question itself, I shall propose some observations, in my conceit, necessarily conducing to the debate of the matter. 1. That we ought to take care to provide for posterity, as our predecessors have done for us: and that this ...