“contribute to” and “lead to”

Question

I'd like to know whether "contribute to" and "lead to" are synonymous expressions in the following:

a. Hard work alone does not necessarily contribute to / lead to success.

Does any contradiction arise in the following?

b. Hard work contributes to success, but hard work alone does not necessarily lead to success.
c. Hard work contributes to success, but hard work alone does not necessarily contribute to success.

I know the repetition of the phrase "contribute to success" in sentence c is somewhat unusual, but I'm concerned only about whether the statement presents a contradiction.

I'd appreciate your help.

Answer 1

Contribute inherently means other factors as well. Because of that, the modifier alone makes the sentence clumsy.

Hard work does not necessarily contribute to success.

Hard work alone does not necessarily lead to success.

Both of those sentences are written correctly, and both mean very similar things.

In the first sentence, you are saying that just because someone works hard does not mean they will be successful (which is obviously true).

In the second sentence, you are saying that JUST working hard, by itself, does not necessarily lead to success - that there are other factors (which is obviously also true).

Your sentence b above is good. Sentence c above implies that success is guaranteed, but hard work may or may not have been a part of it.

Answer 2

In your context, "contribute to" and "lead to" are only partial synonyms.

If hard work "leads to" success, that hard work has very strong influence and there are no (many) obstacles to prevent success.

If hard work "contributes to" success, that hard work has only limited influence and there can be (several) obstacles to prevent success.

So in the case of "hard work" and "success", the better verb is "contributes to", because we already have the experience - many times, only hard work is not enough. Experience, motivation, support, even luck, are also key ingredients to success.