"por lo menos" vs "siquiera"
From my favorite telenovela there have been several episodes where the word "siquiera" was used a lot, and I was expecting to hear "por lo menos". In these conversations one person would be saying something like "you could at least have told me ..." or "at least .... something". These terms seem to be commonly interchangeable, but maybe they are not. I was wondering though, what would cause you to use one over the other? I could have been misunderstanding the conversation, so that's not out of the question either.
I agree with Gekkosan, when watching TV I hear tend to hear "ni siquiera" to mean "not even" quite a lot more than "siquiera" to mean "at least". For "at least" it's usually "por lo menos" or "al menos". Also "ni siquiera" is just shortened to "ni" most of the time too.
I'm not saying that this is a rule of any sort, but I tend to use "siquiera" in the negative: "ni siquiera sabes de qué estoy hablando", "no le dió ni siquiera una oportunidad", "ni siquiera se despidió..."
"Por lo menos escucha mi argumento"; "al menos dame una oportunidad", "¡por lo menos despídete!"
Siquiera and ni siquiera .... positive and negative action. (Dame siquiera un peso) (No tengo ni siquiera un peso).
Por lo menos .... positive action only. (Tengo por lo menos un peso). To make this negative, you would have to say, "Ni por lo menos." It may be gramatically correct, but I have never said this and have never heard it used.
They must be interchangeable synonymic phrases where one would sound more natural than the other depending on what is being said in the conversation.
I discussed this with a Mexican friend and what he said tends to agree with you all. He did say that he almost always used 'por lo menos' and rarely 'siquiera'. I'm almost thinking I may have heard wrong on the telenovela, I probably need to review that particular episode and check my transcribing work. Thanks very much.